BMW K bikes (Bricks)

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1Back to top Go down    Starter sprag clutch problem. on Mon Jan 05, 2015 3:14 pm

subby631

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Hello everyone. I've read previous posts about using diesel engine oil to free the starter motor clutch. The only actual product I've seen named on here and recommended is Shell Rotella but it doesn't appear to be available in the UK. Can anyone recommend another suitable oil please?
Thanks, Ralph.

    

2Back to top Go down    Re: Starter sprag clutch problem. on Mon Jan 05, 2015 7:49 pm

Kyle10

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At the risk of being verbally lanced, I suggest: add a quart of ATF to your crankcase and let 'er idle for about 10 minutes, giving it a goosing now and then in the interim. Drain oil, change filter, re-up with your preferred dinosaur renderings and that'll probably free it up. This is a great and safe way to clean the internals.


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1985 K100rt 0052183
1983 Honda VF750 007713
    

3Back to top Go down    Re: Starter sprag clutch problem. on Mon Jan 05, 2015 7:59 pm

werewasi

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for the benefit of those who haven't got the virus yet, can you describe the manifestations of s s c p and what brings it on . I had the idea that it was something that occurred in cold climate areas where bikes were left sitting in unheated garages


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K100RS 1983 and 1986 (bought a 2nd and put them both together in a dark garage thinking that i would get a heap of parts from the progeny but nothing happened- think they're gay) Laughing Laughing Laughing

1985 K75, Guzzi V7 Special, 1986 GB500, 1974 T500, 1986 MB5 with the whoppa 100cc engine transplant, NC 700 SA Honda, two 1986 Kawasaki BR250s
    

4Back to top Go down    Re: Starter sprag clutch problem. on Mon Jan 05, 2015 9:38 pm

Two Wheels Better

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Any quality Turbo Diesel engine oil ought to do 'the trick'.

Having had a K bike's sprag clutch in my hands and in the dozen-plus intricate pieces of the unit I can say that there is a likelihood that any sprag anywhere could 'gum up' over miles and time if infrequent oil changes are the choice made by the owner. It's at the top of the 'bell housing' and about the furthest away internally from all that fresh, cleaning, dino juice in the oil sump.


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'77 R75/7-1000cc, '87 K100RS, '93 K12 Big Block, '94 R100 Mystic, '03 K1200GT, '04 R1150RT, '06 K1200R, '07 K1200R & '09 K1300GT
    

5Back to top Go down    Re: Starter sprag clutch problem. on Tue Jan 06, 2015 7:14 am

Dai

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The other (and IMHO possibly better but more expensive) alternative is to fill up with flushing oil which is specifically designed to aggressively clean the crap out of engines. Take note of the 500 mile limit though.

TWB is very definately right. When I got LFB the sprag clutch wouldn't engage consistently and because it's an '83 bike, I assumed it was the early type. I stripped the engine only to find that the sprag clutch had already been replaced with the later type. As I have a full service history with my bike (should have looked for the replacement date!) it's a good bet the clutch gummed up sometime during the ten years when the bike only did 9000 miles.

Werewasi: you'll know when you've got it. The starter motor takes off like a demented turbine but the engine doesn't turn over. Sometimes just jabbing at the start button can shock free it off but the chances are you will need to strip the engine and clean the sprag clutch in the very near future afterwards.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

6Back to top Go down    Re: Starter sprag clutch problem. on Tue Jan 06, 2015 10:16 am

japuentes

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Kyle10 wrote:At the risk of being verbally lanced, I suggest: add a quart of ATF to your crankcase and let 'er idle for about 10 minutes, giving it a goosing now and then in the interim. Drain oil, change filter, re-up with your preferred dinosaur renderings and that'll probably free it up. This is a great and safe way to clean the internals.
Or you can use a market flushing aditive. I do so every other oil change.
Best regards
JAP


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1988 K100RS SE/ABS
    

7Back to top Go down    Re: Starter sprag clutch problem. on Tue Jan 06, 2015 4:52 pm

WoodyAUK75

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Also at the risk of being verbally lanced, I'll add my experience.
I changed to full synthetic many years ago, as I liked the idea of only doing one oil change per year. About three years ago, money was a bit tight, so I did a change with dino oil. Yep, starter wouldn't engage. I push started the bike, and when it was hot it worked fine. Changed the oil for synthetic, and after another push to warm her up, have had no problems since.
I have yet to find a scientific reason for this, and have no wish to argue about why it happened, but that was my experience.

    

8Back to top Go down    Re: Starter sprag clutch problem. on Tue Jan 06, 2015 5:03 pm

japuentes

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WoodyAUK75 wrote:Also at the risk of being verbally lanced, I'll add my experience.
I have yet to find a scientific reason for this, and have no wish to argue about why it happened, but that was my experience.
There is a myth around here, If you go from synth to dino or viceversa the mixture woul become crud...to be safe use semi-synth
So on my cars I always use semi-synth or dino.
For the K only dino...
Just to feel safe
Best regards
JAP


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1988 K100RS SE/ABS
    

9Back to top Go down    Re: Starter sprag clutch problem. on Tue Jan 06, 2015 8:17 pm

subby631

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Thanks for your help and suggestions everyone. My bike was parked up for the winter with fresh, fully synthetic oil in it and started up at least once per week until the other day when the clutch wouldn't engage. It is garaged but unheated and the weather has been cold lately.

    

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