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151Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jun 26, 2021 4:16 pm

Danish biker


Platinum member
Platinum member

That was better but still absolutely no clue to what diesel oil is best for:

“I got an old Brick with a none working Sprag clutch”

Some say “find and old tractor oil”. Your links seems to show “up to date 2021 oils”.

When it comes to putting DIESEL engine oil in a GASOLINE engine, I’m a chicken.

    

152Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jun 26, 2021 5:41 pm

moriarti

moriarti
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CLUK CLUK, Very Happy KISS Diesel engines are dirty old things by the way use the fuel, you 
may have seen trucks/buses blowing black smoke from the exhausts. If you drive behind them the smell is very strong and your windscreen will get greasy. Imagine
the greasy oily residue  inside the engine. So to stop the engine from getting FULL OF CRAP ,they developed engine oils with very strong cleaning agents to keep the inside cleaner That means when we need to clean out our petrol engines this oil is ideal for the job.

Diesel fuel oil is # A, a lubricating oil B,a fuel so 2 jobs in 1 product

You can SAFELY USE DIESEL ENGINE OIL in a petrol engine study study cheers Very Happy


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

153Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jun 26, 2021 7:02 pm

Point-Seven-five

Point-Seven-five
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I used Shell Rotella T6 Full Synthetic 15W40 in my bikes for a couple years with good results. I've since switched to Quaker State Ultimate Durability 10W30 Full Synthetic because it's a buck cheaper than Rotella at Walmart.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

154Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sun Jun 27, 2021 1:27 pm

Danish biker

Danish biker
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Point-Seven-five wrote:I used Shell Rotella T6 Full Synthetic 15W40 in my bikes for a couple years with good results.  I've since switched to Quaker State Ultimate Durability 10W30 Full Synthetic because it's a buck cheaper than Rotella at Walmart.

Are we talking DIESEL engine oil or GASOLINE engine oil????

    

155Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sun Jun 27, 2021 3:14 pm

gorio

gorio
Silver member
Silver member
Danish biker wrote:
Are we talking DIESEL engine oil or GASOLINE engine oil????
Rotella is designed for diesel engine primarily but also has additives which are similar to what gasoline engine oils ran 30 years ago.
BMW recommended oils with API rating of SE or SF. The Rotella T4 dino oil 15w40 has an API rating of SN Which is a much newer a stricter approval.

I have ran Rotella dino oil in everything from 1970's airheads to R1200's as well as all my BMW cars. The Dino oil is inexpensive in 20L pails. My engines are all fine clean and well lubricated.

What API says today about the recommended SE, SF rated oils.


SFObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge.
SEObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1979.


__________________________________________________
1992 K100rs 16v
1997 R1100rt
2006 R1200rt
Past lives
Kawasaki Concours
1976 BMW R90s
1975 Ducati 860gt
1992 Honda VFR750
1985 Honda VF750
1982 Kawasaki 750GPZ
1975 Norton 850 Commando
    

156Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sun Jun 27, 2021 4:06 pm

Point-Seven-five

Point-Seven-five
Life time member
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If you look at the reviews for Rotella T6 on sites like Amazon and Walmart you will see that there are many motorcycles using it quite satisfactorily. It has a multi-fuel additive package that allows it to be used in either spark ignition(petrol/gasoline) or compression ignition(diesel) engines.

I like the fact that it is in a 15W40 weight which is fairly close to the BMW spec for my bikes.

A couple years ago I switched to the Quaker State Ultimate Durability 10W30 full synthetic because tests I had seen indicated that the film strength was higher than the Rotella and it lost less of it's film strength at high temperatures. The price is what sealed the deal for me. At Walmart, the Quaker State oil is $20 for 5 quarts while the Rotella is $22 for 4 quarts. Not bad for what the specs say is a better oil.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

157Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 5:04 am

Danish biker

Danish biker
Platinum member
Platinum member
gorio wrote:




SFObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge.
SEObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1979.

Excuse my ignorance but this a warning NOT to use diesel oils (SF and SE…..not even sure what that means)?

    

158Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 7:51 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Danish biker wrote:
gorio wrote:




SFObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge.
SEObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1979.

Excuse my ignorance but this a warning NOT to use diesel oils (SF and SE…..not even sure what that means)?

Those are not compression ignition(diesel) engine oils, but obsolete spark ignition(petrol/gasoline) engine oils.

The designations are generated by the American Petroleum Institute (API) which is an industry trade organization.  The first letter in the oil grade tells you what it's designed for.  S is for spark ignition engines, and C is for compression ignition engines.

The second letter designates the generation of the specification and the additive package requirements.  The sequence started with A, and progresses through the alphabet.  The specifications change in response to the requirements of the metallurgy and operating conditions as engine design advances through the years.

The major driving force in additive development is the requirement for emissions reduction.  For example, zinc was a very popular anti-wear additive, and was common in older oil specifications, but since it damages catalytic converters, the amount permitted has been reduced over the years and it has been replaced by other additives.

Another requirement that has changed is the ability of the oil to avoid loss of film strength and carbonization at the high temperatures it is exposed to in modern turbocharged and supercharged engines. Older oils do not have the stabilizers found in new oils.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

159Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 12:03 pm

Danish biker

Danish biker
Platinum member
Platinum member
Point-Seven-five wrote:
Danish biker wrote:
gorio wrote:




SFObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge.
SEObsoleteCAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1979.

Excuse my ignorance but this a warning NOT to use diesel oils (SF and SE…..not even sure what that means)?

Those are not compression ignition(diesel) engine oils, but obsolete spark ignition(petrol/gasoline) engine oils.

The designations are generated by the American Petroleum Institute (API) which is an industry trade organization.  The first letter in the oil grade tells you what it's designed for.  S is for spark ignition engines, and C is for compression ignition engines.

The second letter designates the generation of the specification and the additive package requirements.  The sequence started with A, and progresses through the alphabet.  The specifications change in response to the requirements of the metallurgy and operating conditions as engine design advances through the years.

The major driving force in additive development is the requirement for emissions reduction.  For example, zinc was a very popular anti-wear additive, and was common in older oil specifications, but since it damages catalytic converters, the amount permitted has been reduced over the years and it has been replaced by other additives.

Another requirement that has changed is the ability of the oil to avoid loss of film strength and carbonization at the high temperatures it is exposed to in modern turbocharged and supercharged engines.  Older oils do not have the stabilizers found in new oils.

Thank you very much probably a bit beyond my understanding and also my technical English is not perfect.

However my main question is what you think about the oil I’m using now (picture)

Starter or Sprag clutch failure  - Page 4 Dfff7f10

    

160Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 2:01 pm

mike d

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Does it state what the API specification is?

miKE

    

161Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 3:04 pm

Point-Seven-five

Point-Seven-five
Life time member
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Being a high zinc content oil, I would guess that it probably has a SC or SD rating.  I assume the bike spends most of it's time in Northern Europe so the oil temperature shouldn't be running too high.  The bike(which I can't find a year or model), if it's an early model K, doesn't have a catalytic converter so the zinc anti-wear shouldn't cause any problems.  

As long as the sludge in the sprag has been completely flushed this oil will work.  Just change it before 10,000km(I would do it at 6,000km).  I suspect the previous owner didn't change the oil often enough to prevent the oil breaking down and forming the sludge that messed up your sprag.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

162Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 4:58 pm

Laitch

Laitch
Life time member
Life time member
Point-Seven-five wrote:The bike(which I can't find a year or model), if it's an early model K, doesn't have a catalytic converter so the zinc anti-wear shouldn't cause any problems.
mike d wrote:Does it state what the API specification is?
He has a 1992 K1100RS but it's a European model so probably doesn't have a converter. According to MPM's website, the oil has an API spec of CF/SL.


__________________________________________________
1995 K75 81,000 miles
Starter or Sprag clutch failure  - Page 4 Usa-lo10
    

163Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jun 28, 2021 7:21 pm

Point-Seven-five

Point-Seven-five
Life time member
Life time member
According to the MPM oil press release:

"For modern vehicles equipped with an exhaust gas after-treatment system due to meet environmental requirements, the amount of zinc/phosphorous is substantially lower than is desirable for most classic car engines. An oil with a high zinc/phosphorus-content, such as the MPM Classic High Zinc product, reduces the service life of these systems considerably. "

It surprises me that a high zinc oil can get an API SL rating since the press release warns that this oil "reduces service life...considerably" of Catalytic converters. I kinda admire how the copywriters obfuscated this information. Classic sleaze marketing.

As long as the original poster doesn't have a catalytic converter on his bike this oil should be okay.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

164Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Sprag Slipping Tue Jun 29, 2021 2:49 am

daveyson

daveyson
Life time member
Life time member
It's probably OK usually. 

Zinc is a friction reducing additive. I wouldn't want friction reducing additives with a clutch slipping problem, and it's high zinc to boot. 

I think in a previous thread you said you changed your  oil which completely eliminated the slipping clutch problem, but now your using high zinc oil and it's slipping again. Maybe try another oil or go back to the one that worked.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

165Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 02, 2021 9:19 am

Danish biker

Danish biker
Platinum member
Platinum member
Ok it worked for 5 and a half day. Probably shortest period ever. The WD40 job would normally work for a month. 

Any way last try before taking out the sprag will be:

Take crank cover off. 

Spray carburetor cleaner (unfortunately I can only get the combustible stuff) into the 3 small holes, and tap between the gear teeth with a flat headed screwdriver. Maybe 3 times in each hole. 

Crank cover on. 

Run engine for 5 minutes at 1.500 rpm. 

Drain oil, replace filter. 

Put in DIESEL engine oil

    

166Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 02, 2021 6:16 pm

moriarti

moriarti
Life time member
Life time member
Hi Bro, If you can purchase CLUTCH/BRAKE cleaner its does a better job and WONT blowup Did a mates 75s last week used 2 FULL CANS to really get it clean. Finish off with WD40 this will put some lubrication back into the sprag .  Very Happy Very Happy


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

167Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jul 03, 2021 4:14 am

Danish biker

Danish biker
Platinum member
Platinum member
moriarti wrote:Hi Bro, If you can purchase CLUTCH/BRAKE cleaner its does a better job and WONT blowup Did a mates 75s last week used 2 FULL CANS to really get it clean. Finish off with WD40 this will put some lubrication back into the sprag .  Very Happy Very Happy

I got this

Starter or Sprag clutch failure  - Page 4 20d22810

On a side note (besides freaking out), I’m thinking: “What is the same on both engines/bikes that could cause both sprags to fail the exact same way???”

Might be a long shot.  But the battery is the same. And as fare as I remember failure in power (lack of amp) can cause a starter to spin “slower/lower” and therefor the sprag is not spinning fast enough to get a grip????

    

168Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jul 03, 2021 6:32 am

moriarti

moriarti
Life time member
Life time member
Product looks OK to me. Having spoken to our local K Guru (ANDY) he has seen this problem with well serviced and neglected bikes with High and Low mileage, so no definite reason. Iv had low/flat batteries in the past but not the same symptom's as the sprag. Very Happy


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

169Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jul 03, 2021 3:13 pm

Danish biker

Danish biker
Platinum member
Platinum member
moriarti wrote:Product looks OK to me. Having spoken to our local K Guru (ANDY) he has seen this problem with well serviced and neglected bikes with High and Low mileage, so no definite reason. Iv had low/flat batteries in the past but not the same symptom's as the sprag. Very Happy

The battery theory is maybe me going fishing, but I’ll leave no stone unturned. 

It would be total FUBAR to take everything  apart and put in a new sprag just to experience the problem again because of lack of power.

    

170Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Sat Jul 03, 2021 4:19 pm

Laitch

Laitch
Life time member
Life time member
Danish biker wrote:I got this

Starter or Sprag clutch failure  - Page 4 20d22810
There are brake cleaners that don't have inflammable vapors. The product in the photo is not one of them. It's classified H225 in the USA which means its vapors can ignite.


__________________________________________________
1995 K75 81,000 miles
Starter or Sprag clutch failure  - Page 4 Usa-lo10
    

171Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jul 05, 2021 4:42 am

Danish biker

Danish biker
Platinum member
Platinum member
What a way to start 4 weeks vacation. Doing the carburetor cleaner thing.

Starter or Sprag clutch failure  - Page 4 2d39ff10


__________________________________________________
You have enemies? Good. That means you've stood up for something, sometime in your life.
-Sir Winston Churchill
    

172Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jul 05, 2021 6:40 am

92KK 84WW Olaf

avatar
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Life time member
Danish biker wrote:Ok it worked for 5 and a half day. Probably shortest period ever. The WD40 job would normally work for a month. 

Any way last try before taking out the sprag will be:

Take crank cover off. 

Spray carburetor cleaner (unfortunately I can only get the combustible stuff) into the 3 small holes, and tap between the gear teeth with a flat headed screwdriver. Maybe 3 times in each hole. 

Crank cover on. 

Run engine for 5 minutes at 1.500 rpm. 

Drain oil, replace filter. 

Put in DIESEL engine oil
4 years ago had issues on my 84 K100RT. tried the 3 hole trick only to discover my sprag clutch had no holes, early ones are different.

I did a series of very frequent oil changes [less than 1,000 mile intervals]. In the meantime I also decided to go back to mineral oil 20w50 and the problem never came back. I am using this in my 83 K100RS too.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

173Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jul 05, 2021 11:28 am

Danish biker

Danish biker
Platinum member
Platinum member
92KK 84WW Olaf wrote:

4 years ago had issues on my 84 K100RT. tried the 3 hole trick only to discover my sprag clutch had no holes, early ones are different.

I did a series of very frequent oil changes [less than 1,000 mile intervals]. In the meantime I also decided to go back to mineral oil 20w50 and the problem never came back. I am using this in my 83 K100RS too.

I tried a mineral oil after the cleaning with diesel fuel. Did work for more then 5 1/2 days. Now I’m on diesel oil.

    

174Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jul 05, 2021 11:42 am

Danish biker

Danish biker
Platinum member
Platinum member
Ok short update. After the crazy diesel fuel cleaning (must admit running the bike hot with only 25 % engine oil and 75 % diesel fuel freaked me out and that can’t be good for a engine) the sprag worked for 5 1/2 day.

Today I took the crankshaft cover off and sprayed, and sprayed, and sprayed the 3 holes in the spraghousing with carburetor cleaner.

Then drained the mineral oil.

Took out the oil filter.

Put in DIESEL engine oil and new filter.

Took a long ride. Looked like the bike got a bit hotter (on the gage) with the diesel oil.

The only thing that hasn’t been tried (except for replacing the sprag) is a new battery. 

So my absolute last resource is putting a newer and better battery on the bike. So if the sprag fails again I’ll try this. If it doesn’t work I know I’m SOL.

Now while going through a box with spare parts and parts from the old engine, that also had many, many sprag issues, I actually found the sprag. Apparently I took it out of the old engine last year. Actually I thought it was still in the engine.

@88 says it looks brown and I should clean it and put it in my present engine. I’m probably thinking that if I have to go through the big job of replacing a sprag I should probably spend money on a new one?

[url=https://servimg.com/view/19734465/36]Starter or Sprag clutch failure  - Page 4 13d1a610

[url=https://servimg.com/view/19734465/36]

    

175Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Mon Jul 05, 2021 2:52 pm

moriarti

moriarti
Life time member
Life time member
DONT PANNIC Bro,you getting Freaked out wont bother the engine Very Happy
Nether will the 25/75% mix. You really tried you best to get this right. Last hope is to follow Olafs advise before you start to strip down. I would wait until i had both Sprags on the bench fully cleaned before spending good money. Im asking now would a SONIC cleaner be a good idea. Chatter

There are a few video's on you tube how DIY them


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

176Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 5:43 am

Danish biker

Danish biker
Platinum member
Platinum member
moriarti wrote:DONT PANNIC Bro,you getting Freaked out wont bother the engine Very Happy
Nether will the 25/75% mix. You really tried you best to get this right. Last hope is to follow Olafs advise before you start to strip down. I would wait until i had both Sprags on the bench fully cleaned before spending good money. Im asking now would a SONIC cleaner be a good idea. Chatter

There are a few video's on you tube how DIY them

Before I go with Olaf’s advice I’ll go with yours (I think it was) and ride with Diesel engine oil for a longer time.

Regarding cleaning I’m sure I need to take the sprag out of the housing. 

How ever until yesterday I thought the sprag worked this way:

Starter spins sprag housing. The centrifugal force pushes out the smal “claws” and they grip on to the axel on the crankshaft and turns it and the engine starts. 

How ever centrifugal force would rather move the “claws” back into the sprag housing, then out to the middle. 

Some Danish guy on a BMW K75/100/1100 told me I was wrong. Actually my problem is the claws on the sprag doesn’t release something, like it is supposed to every time I stop the engine. 

As long as I don’t even know how a sprag works I’ll probably never fully understand what I’m doing (or if the advice given to me actually is based on knowledge or just speculation).

    

177Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 9:54 am

moriarti

moriarti
Life time member
Life time member
Easy Tiger Very Happy You have a spare sprag that you can work with as a test run.The srag works more on the INERTIA principle rather than centrifugal, When the engine is running the sprag is in Neutral free spinning. When the engine stops the sprag returns to its Engaged position ready to spin the engine. Damage/Residue buildup will prevent the sprag returning to Engaged position,Then the bugger wont start
90%knowlage 10%speculation.If i was with you it would be 99% gray matter.By striping your spare sprag you can learn a lot and identify damage if any  Very Happy Very Happy Sleep Sleep


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

178Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 10:29 am

Point-Seven-five

Point-Seven-five
Life time member
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With all due respect, the Sprag works on the principle of frictional drag between the eccentric "rollers" and the driven ring, not inertia.

When the starter is running, the driving ring is moving faster than the output ring. The friction between the driving ring and the sprag "rollers" causes them to roll slightly. Because they a not perfectly round, they jam between the driving ring and the output ring. This solidly connects the to rings together so the starter can spin the engine to start it.

Once the engine starts, the output ring starts moving faster than the driving ring and the friction between the "rollers" and the rings causes them to rotate to where the contact force between the "rollers" and the rings allows them to disengage. There are small springs in the sprag to assist in creating the friction to start the engagement.

The problem in the sprag comes from lack of friction between the "rollers" and the rings. Dirt in the "roller" pivots will prevent them from getting enough contact pressure with the driving ring to rotate them into the jammed position. This is why you need to clean the sprag to get it working.

Another failure mode is when friction reducing compounds get into the sprag. In my experience this is rare and in my case it was because I had used a lot of molybdenum assembly lube when I did a cylinder head rebuild. The molybdenum is very slippery and bonds to the metal. When it go into my sprag it prevented engagement until I was able to clean it out. It was the flushing procedure that I recommended earlier that made it possible to get the sprag working properly again.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

179Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 10:50 am

Danish biker

Danish biker
Platinum member
Platinum member
Point-Seven-five & Moriarti

Thanks a lot for taking the time. My technical English, how ever, gives me some blind spots in your fine detailed answer. I’ll read both posts a few more times.

Tomorrow I’ll be going to our countries 4. larges city (only considered a huge town in other parts of the world 😂).

How ever it has a BMW shop (mechanic). I ordered a crankshaft cover seal. I’m bringing my sprag and hope the mechanic will:

1. Explain what exactly happens (in Danish), so I can fully understand.

2. Will take a quick look and tell me either:

a). It’s extremely dirty now wonder it doesn’t work!

Or:

b). The dirt (brown stuff) you see is nothing. It’s not dirt that is preventing it from disengaging.

Hoping I got the part right that it actually doesn’t lock on to something, when i hit the starter but when the engine is turned off.

On a side-note:

Took a longer run yesterday and today. A few times the sprag didn’t catch (lock) when the starter was engaged but after a second or two holding the starter button down it did. Not a good sign. After all the work it should “act normal” for a moth or so.

I’m still wondering if a starter relay or a week battery has any meaning in all this. But after your explanation I can’t grasp on to that hope. Why would lack for power prevent a sprag from locking on to something, when the engine is turned off.

Oh boy I’m on VERY thin ice.

    

180Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 11:51 am

moriarti

moriarti
Life time member
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Before you meet the Mechanic write down some of you questions so you dont forget  anything. you can try this as well. When the sprag fails Stab the starter button 1/2 seconds instead of holding the button down this might help it to engage 
Enjoy your time in the City large or small. Very Happy Very Happy
I/WE cant wait for the report on your SPRAG,If nothing else it will polish up and make a good ornament for the garage roundel


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

181Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 11:56 am

moriarti

moriarti
Life time member
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Point-Seven-five wrote:With all due respect, the Sprag works on the principle of frictional drag between the eccentric "rollers" and the driven ring, not inertia.

When the starter is running, the driving ring is moving faster than the output ring.  The friction between the driving ring and the sprag "rollers" causes them to roll slightly.  Because they a not perfectly round, they jam between the driving ring and the output ring.  This solidly connects the to rings together so the starter can spin the engine to start it.

Once the engine starts, the output ring starts moving faster than the driving ring and the friction between the "rollers" and the rings causes them to rotate to where the contact force between the "rollers" and the rings allows them to disengage.   There are small springs in the sprag to assist in creating the friction to start the engagement.

The problem in the sprag comes from lack of friction between the "rollers" and the rings.  Dirt in the "roller" pivots will prevent them from getting enough contact pressure with the driving ring to rotate them into the jammed position.  This is why you need to clean the sprag to get it working.  

Another failure mode is when friction reducing compounds get into the sprag.  In my experience this is rare and in my case it was because I had used a lot of molybdenum assembly lube when I did a cylinder head rebuild.  The molybdenum is very slippery and bonds to the metal.  When it go into my sprag it prevented engagement until I was able to clean it out.  It was the flushing procedure that I recommended earlier that made it possible to get the sprag working properly again.
I gladly stand corrected it was the way i could think of to describe it Very Happy  


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

182Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 2:02 pm

92KK 84WW Olaf

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How ever it has a BMW shop (mechanic). I ordered a crankshaft cover seal. I’m bringing my sprag and hope the mechanic will:......




Did you order the O ring and other parts needed?


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

183Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 4:35 pm

Danish biker

Danish biker
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92KK 84WW Olaf wrote:Did you order the O ring and other parts needed?

Don’t freak me out. What o-ring???

    

184Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 4:41 pm

Danish biker

Danish biker
Platinum member
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moriarti wrote:Before you meet the Mechanic write down some of you questions so you dont forget  anything. you can try this as well. When the sprag fails Stab the starter button 1/2 seconds instead of holding the button down this might help it to engage 
Enjoy your time in the City large or small. Very Happy Very Happy
I/WE cant wait for the report on your SPRAG,If nothing else it will polish up and make a good ornament for the garage roundel

Bwahahaha 😂😂😂

I normalt stop hitting the starter button when it spins, but today I had music in my helmet so…….

    

185Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Tue Jul 06, 2021 5:07 pm

92KK 84WW Olaf

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Danish biker wrote:
92KK 84WW Olaf wrote:Did you order the O ring and other parts needed?

Don’t freak me out. What o-ring???
You have to take off the O ring to get at it. Its not reusable.

These are from Motorworks. Also the clutch bolts are single use stretch bolts and are not part of the clutch plate kit..




Output shaft to clutch carrier O-ring | ENA60456
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__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

186Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Wed Jul 07, 2021 4:17 am

Danish biker

Danish biker
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92KK 84WW Olaf wrote:
Danish biker wrote:
92KK 84WW Olaf wrote:Did you order the O ring and other parts needed?
You have to take off the O ring to get at it. Its not reusable.

These are from Motorworks. Also the clutch bolts are single use stretch bolts and are not part of the clutch plate kit..
Thanks brother. I thought you where talking about a o-ring for the crankshaft cover, since I mentioned I was picking that up today.

    

187Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Thu Jul 08, 2021 11:45 am

Danish biker

Danish biker
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I’m in the process of cleaning the sprag from the engine that blew up. And very happy that I finally understand how it works. From the pictures do you think it would be ok to put it back together after first cleaning with break cleaner and the ultrasound, or do you think it looks worn??

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188Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Thu Jul 08, 2021 12:33 pm

Laitch

Laitch
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My first impression is that I'd take your photo of the sprag cage to a graphic artist to be photographed, resized to a 70mm diameter image of the cage then converted to a durable, weatherproof adhesive image that I would use to replace the BMW roundels on my moto's tank. cheers

It's difficult for me to inspect it from here no matter how close I get to my computer's terminal; however,  that's one of the best photos of a translucent pan with murky liquid in it that I've ever seen. Have you disassembled all the sprags from the cage then cleaned everything, including the springs, thoroughly?


__________________________________________________
1995 K75 81,000 miles
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189Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Thu Jul 08, 2021 1:06 pm

Danish biker

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Laitch wrote:Have you disassembled all the sprags from the cage then cleaned everything, including the springs, thoroughly?

Are you kidding me 😂😂😂

I would loose a spring and 5 sprags 😎

Nope I’ve hosed it down repeatedly with break cleaner and ultrasound cleaned several times.

I’m not sure a guy like me should go further 😜

    

190Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 4:40 am

Danish biker

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Still struggling to understand the sprag.

I finally found out that it is the outer side of the sprags that actually locks on to the inner side of the ring. Up till now I thought it was the inside teeth of the sprag that turned something.

So when looking at the schematics I can really not figure out what the inside of the sprag (teeth) engages (locks to). If they in fact  do lock on to anything at all???

Please don’t write: “They lock on to the disconnector-champshaft-freewheel-assembly-gear!” My technical English is not very good so I would probably not know what your are talking about. So either a picture of what it locks on to or just plain: “The inside of the sprag doesn’t lock on to anything!” 😂

PS as you might be able to see the inside of the ring looks worn. Be aware this is the sprag from the engine that blew up. Not the one on my present engine.

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191Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Sprag Fri Jul 23, 2021 4:57 am

daveyson

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See the bit (boss) on the left side of gear number 9, thats what the inside of the sprags lock on to.

So while cranking 3,5 and 9 all turn together. When you release the start button, the starter and the free wheel (3) stop turning.

Edit freewheel (9)



Last edited by daveyson on Fri Jul 23, 2021 7:04 pm; edited 1 time in total


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

192Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 7:30 am

Danish biker

Danish biker
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daveyson wrote:See the bit (boss) on the left side of gear number 9, thats what the inside of the sprags lock on to.

So while cranking 3,5 and 9 all turn together. When you release the start button, the starter and the free wheel (3) stop turning.

The diameter on the space between the teeth are from 35 to 40 millimeter. 

So are you telling me that the teeth on #9 will fit into a 35-40 mm hole?

Maybe it is the schematic (scale) but the diameter on #9 looks way larger then 40 mm??? Starter or Sprag clutch failure  - Page 4 Ff73ac10

    

193Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Sprag Fri Jul 23, 2021 8:16 am

daveyson

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Not the teeth but see the left bit of #9 that looks like a shaft, the sprag clutch fits over it, so the sprag locks the two gears together while cranking.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

194Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 8:18 am

Laitch

Laitch
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Danish biker wrote:So are you telling me that the teeth on #9 will fit into a 35-40 mm hole?
Maybe it is the schematic (scale) but the diameter on #9 looks way larger then 40 mm???
The diagram isn't a blueprint. It is not drawn to scale. It is used to indicate the approximate assembly position of the parts but, despite everything, you seem to be understanding the concept. Apparently you aren't into the engine yet.

Do you want me to expand on daveyson's concise description with the Hans Christian Andersen version?Smile


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1995 K75 81,000 miles
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195Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 10:12 am

Danish biker

Danish biker
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Laitch wrote:Do you want me to expand on daveyson's concise description with the Hans Christian Andersen version?Smile

😂😂😂😂

So this goes into this?

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196Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 10:18 am

Laitch

Laitch
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Danish biker wrote:So this goes into this?
If by this you mean that, yes! Smile


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1995 K75 81,000 miles
Starter or Sprag clutch failure  - Page 4 Usa-lo10
    

197Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 10:45 am

Danish biker

Danish biker
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Laitch wrote:
If by this you mean that, yes! Smile

Tomato - Tomateo
Potato - Potateo

😂😂

So this drawing that was posted earlier is actually wrong, since the gear #9 is visible and actually not hidden inside the sprag housing???

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198Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 2:37 pm

Laitch

Laitch
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Danish biker wrote:So this drawing that was posted earlier is actually wrong, since the gear #9 is visible and actually not hidden inside the sprag housing???
How can that diagram be wrong? I created that attractively modified diagram.   Starter or Sprag clutch failure  - Page 4 177381 Are you sure you don't want the HCA version now?

The teeth of Gear #9 engage with the gear on the countershaft that is rotated by the starter's gea; the teeth of the Gear #9 are exposed so that the countershaft gear teeth engage with them. What is hidden from view is the hub—what daveyson refers to as the boss—of Gear #9. The hub of Gear #9 is within the sprag cage and is what the sprags grab. The green arrow I've added to your attractively modified diagram indicates the hub.
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__________________________________________________
1995 K75 81,000 miles
Starter or Sprag clutch failure  - Page 4 Usa-lo10
    

199Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 3:35 pm

Danish biker

Danish biker
Platinum member
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Laitch wrote:
How can that diagram be wrong? I created that attractively modified diagram.   Starter or Sprag clutch failure  - Page 4 177381 Are you sure you don't want the HCA version now?

Nothing wrong with the diagram, just my understanding it. I guess I’ll have to look at the exploded engine (it’s been rapped in plastic for a year now). My problem is I am not sure how the F the gear on #9 will fit into the SMALL 35 mm sprag housing. Secondarily my technical English is sooo bad I don’t understand words like:

“The teeth of Gear #9 engage with the gear on the countershaft that is rotated by the starter's gea; the teeth of the Gear #9 are exposed so that the countershaft gear teeth engage with them.”

Or “hub” no idea what that is. Yes totally my bad. I know.

And that is only my fault. You have been so outstanding explaining and giving information.👍👍👍👍👍

I still just don’t see (yet) how the huge gear on #9 will fit into the 35 mm hole in the sprag housing. And I’m talking about the gear (teeth on the largest part of #9, NOT the smaller smooth round part sticking out).

I guess I’ll just have to look at my exploded engine. My brain just can’t understand the gear (outer ring) on #9 will fit into the sprag housing. I guess it is just that simpel, that the #9 gear is way much smaller in diameter then it looks on any of the drawings.

PS if the “hub” is the smooth round thing, with out gears I can understand it will fit into the sprag housing, but then I’m totally confused. Why does the sprag have “cuts / teeth” if they only lock on a round smooth surface???

PPS does the teeth (picture with red arrows) lock on red or blue arrow on drawing?

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200Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 4:10 pm

Point-Seven-five

Point-Seven-five
Life time member
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The sprag locks onto the smooth part of #9.

The friction between the sprag cams and the smooth part of #9 cause them to lock onto the smooth surface. They grip the smooth part the same way the wheels of a train engine grip the rails under it. Because of the way they are shaped, the more friction there is the harder they grip. Once the engine starts the sprag is moving faster than the #9 gear and the cams release.

Have you ever seen the type of door stop that flips down and holds the door? The harder you pull on the door the harder it grips on the floor to hold the door open. The sprag works on the same principle. Each one of the cams in the sprag is like that door stop.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

201Back to top Go down   Starter or Sprag clutch failure  - Page 4 Empty Re: Starter or Sprag clutch failure Fri Jul 23, 2021 5:35 pm

Danish biker

Danish biker
Platinum member
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Point-Seven-five wrote:The sprag locks onto the smooth part of #9.  

The friction between the sprag cams and the smooth part of #9 cause them to lock onto the smooth surface.  They grip the smooth part the same way the wheels of a train engine grip the rails under it.  Because of the way they are shaped, the more friction there is the harder they grip.  Once the engine starts the sprag is moving faster than the #9 gear and the cams release.  

Have you ever seen the type of door stop that flips down and holds the door?  The harder you pull on the door the harder it grips on the floor to hold the door open.  The sprag works on the same principle.  Each one of the cams in the sprag is like that door stop.


Sorry for my total ignorens 😂😂

And Viking (I don’t need no BS) 😂😂

Do the teeth on my picture in last post, with the 3 red arrows lock on the blue arrow or the red arrow part on the drawing??????

And i ask in this rude no BS way, because I just don’t understand many of the technical explanations (sorry my bad).

But keep it KISS. Blue arrow or red arrow?????

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