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1Back to top Go down    Fuel consumption on Thu Feb 04, 2016 9:47 am

Dave

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I've had my 1987 K100 for a few tank fulls of petrol and I'm disappointed in the fuel consumption. First tank full was 45mpg, second 37mpg. The bike is running very well otherwise. What could be causing such poor figures?

I'm not mechanically gifted but would like a few ideas to try before I take it in to my mechanic. Thanks in advance.


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Dave  Very Happy  

1987 K100rs
2009 R1200R
    

2Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 10:15 am

brickrider2

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I'd first consider the easy and obvious possibilities: tire pressure and dragging brakes.  
If that doesn't give you some answers, what does the end of the silencer look like?  Sooty, as in running too rich?

    

3Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 11:39 am

Chocolate

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Like brickrider has said, your way of riding.
For Some of us this is normal autobahn, breaking, Adjust the valve clearance to fit within service.
Air filter is dirty. Check the compression!

My consumption is around 51 mpg UK, 61 mpg US and 4.6 kml
But I'm picking flowers on the way :-)
Yours is 45 mpg UK, 37.5 mpg US and 6.3 kml

It could be, besides some other things you fuel injectors, they could be dripping instead of spraying.
The pistol rings could be done.
There could be wrong timing.
Do you have black smoke coming out the pips?

If you need some new good and tested four hole injectors instead of one hole old injectors, I have got some, could ship to UK, price shouldn't be bad.

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Cheers



Last edited by Chocolate on Thu Feb 04, 2016 12:49 pm; edited 1 time in total


__________________________________________________
Only a few activities make me experience my senses in a way motorcycle riding does, it is like swimming in the nude in a river.
K75 BA/1992 ABS, K75 BA/1991 noABS, Ducati, Mobylette M1/1973
Pictures: Me my bike and I
    

4Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 12:42 pm

Dave

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Thanks.  Brakes ok,  exhaust clean. Riding style is relaxed, not in a hurry to get anywhere nowadays!!!  I'm going to have a go at changing the air filter and spark plugs.  The injectors and valves are beyond my capabilities.  I'm getting a Mahle air fi!ter, but what plugs: Champion or Bosch?


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Dave  Very Happy  

1987 K100rs
2009 R1200R
    

5Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 1:43 pm

duck

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Swapping fuel injectors is pretty easy. (and a good idea)

Just be sure to blow some compressed air or vacuum around their bases before removing them from the engine.  Sometimes there is dirt or tiny rocks around the bases of them which you don't want falling into the cylinder head when you remove the injector.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

6Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 2:41 pm

Chocolate

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Realy easy to remove, 2 screws and pull, sometimes you have to use some oil and a grip tong.

Remove injectors
http://www.motobrick.com/index.php?topic=3781.0

Video showing the spray picture with one hole


Cheers


__________________________________________________
Only a few activities make me experience my senses in a way motorcycle riding does, it is like swimming in the nude in a river.
K75 BA/1992 ABS, K75 BA/1991 noABS, Ducati, Mobylette M1/1973
Pictures: Me my bike and I
    

7Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 5:26 pm

duck

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More info on fuel injectors:
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/fis/fis.htm

I have the four hole injectors in several of my Ks. They work fine but I'm not convinced they're much better than a good set of original ones. I've experienced no noticeable change in fuel mileage or power.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

8Back to top Go down    Re: Fuel consumption on Thu Feb 04, 2016 6:17 pm

Holister

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Just my 2 cents worth but I feel you're better sticking with the injectors you have. They are highly reliable and last for around 300 to 400 thousand kilometers. If your bike has had a history of having been sitting around unused for an extended period then it could be they need a clean (see Youtube or get them done professionally). A leaking injector will add to your fuel consumption but may not make any appreciable difference to your tailpipe. Check each sparkplug for deposits over a few weeks instead. You could also pull the injectors and rail out and observe for leaks under presure.
Read this: 1 hole Vs 4 hole injectors

Sparkplugs will definately affect consumption and need changing regularly. I find mine last no more than 10K klm. You'll get a slight uneveness at start and a bit more vibration than normal thru the bars. Use a DMM set to 20 ohms range. They should read less 0.5ohm or less from connector to electrode. Keep any good ones as spares and replace with new SPs. If you have OEM resistor leads then you'll need NKG D7EA plugs. Don't use DR7EA plugs with resistor leads.
Make sure your plugs have the 'terminal nuts' screwed on and they're tight. you won't get a proper lead/plug connection without them and this will dramatically affect the quality of the spark and combustion.
One thing that is often forgotten is to nip up the SPs after a hundred klm or so as the compression washer will squash out a bit. Gummy SP thread and stains around the ceramic base is evidence of combustion gases blowing past.

If your consumption is high and eratic, its a sure bet your valve shims need adjusting. Its not hard to do. Chris Harris on Youtube explains and demonstrates the process well... don't mind his language, he knows his sh!t. Very Happy
There's a special tool to get your shims out and its pretty cheap. Try searching this forum to find the link.
Apart from other symptoms, I had very high and eratic consumption from 6 to 8 Lit/100 km. Valve shim adjustment brought that down to around 5.3 ±0.3

Engine oil can play a part in fuel consumption also and I've found that a good full synthetic oil can reduce your consumption by up to 10%. Fuel savings can more than pay for the cost of the oil. I'm currently using Nulon full synthetic which has a moly content. There is a down-side. If your seals and gaskets are in poor condition you can get oil weeping. Synthetic oil molecules are much smaller than in mineral oils.

Currently my consumption varies between 4.4 and 5.4 lit. Its become eratic again over the last 6 months or more. I get a lot of noise from the timing chain so I'm suspecting the valve timing may be changing slightly under different conditions. Have just recieved a new kit from Motorworks and will be fitting that next week so I'll let you know how that goes.


__________________________________________________
1988 K100RT     VIN No.  0094680
1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
     Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

9Back to top Go down    Re: Fuel consumption on Fri Feb 05, 2016 11:40 am

Dave

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Thanks guys. Redex, air filter and spark plugs ordered.


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Dave  Very Happy  

1987 K100rs
2009 R1200R
    

10Back to top Go down    Re: Fuel consumption on Mon Feb 08, 2016 10:33 pm

gabriel


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This topic interests me because I might have issues with my bike's fuel consumption.
My 1984 k100 was taken off the road due to the gearbox grub screw issue.
I fixed that problem then decided to overhaul the water pump.
Of course the threaded section of the shaft broke when I was removing it from the pump.
I visited a Ktm dealership in hoppers crossing and to my amazement, the owner placed the shaft in a metal lathe and replaced the threaded section.
I had purchased three of the original design water seals two years ago from Motobins and was determined to use them.
There was no issue installing the seals. I used Reinzosil to seal the joint and the overhaul was a success.
No leaks whatsoever.
My issue now is the fuel consumption.
I haven't measured it, but the end of my exhaust is sooty and don't know how to adjust the fuel mixture.
Thank you for your assistance.

    

11Back to top Go down    Re: Fuel consumption on Tue Feb 09, 2016 3:02 am

RicK G

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Using unleaded fuel will always give you a black sooty exhaust pipe.
The mixture can be adjusted but I would not recommend doing it unless things get drastic. One common cause with EFI engines is a failing temperature sensor that makes the ECU think the engine is still cold so it keeps the mixture rich. There are quite a number of threads about it here and there is a graph showing what resistance the sensor should read at various temperatures in the downloads section.
Even putting new plugs in can improve things quite a bit but one thing that doesn't have any effect on fuel consumption on an EFI engine is the condition of the air filter except if it is totally blocked. The air is measured after the filter and the filters on most bikes and cars will flow a heap more air than they are usually required to pass.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

12Back to top Go down    Re: Fuel consumption on Tue Feb 09, 2016 4:30 am

charlie99

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a good multimeter is a must  for any of the electrical issues we see with k bikes

the easiest way to test the temp sensor is at the under seat computer  pins 10 and 13

have a read of the posts in the forum about this before you try anything

good luck


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

13Back to top Go down    Re: Fuel consumption on Tue Feb 09, 2016 6:55 am

Holister

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Just a thought after you've checked out the suggestions above. If the sump is over filled you can get get a thick sooty deposit on the tailpipe. The exhaust will also smell heavily. My PO had over filled by nearly a litre of oil. Took me a while to work out what was causing the soot... but that was before I found K100-forum.com Very Happy


__________________________________________________
1988 K100RT     VIN No.  0094680
1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
     Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

14Back to top Go down    Re: Fuel consumption on Tue Feb 09, 2016 7:50 am

RicK G

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VIP
That brick of yours was a poor pathetic thing when you got it Nigel and you have transformed its life and made it happy again, like it should be for all bricks


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

15Back to top Go down    Re: Fuel consumption on Tue Feb 09, 2016 8:56 am

Holister

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Very Happy  Ha ha! With much help and enthusiasm from fellow bricksters.
The sweet thing got a new timing chain today. All went well except for a stripped head on one of the casing bolts. Covers back on tomorrow and hopefully she'll be purring instead of rattling her old bones bits. I'm also hoping I'll see an end to eratic fuel consumtion.
Cheers


__________________________________________________
1988 K100RT     VIN No.  0094680
1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
     Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

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