I have a 1997 MC28 repsol and it has decided over the space of a month or than wont go over 1/4 throttle without dieing. This happens in any gear and any rpm. (it will rev it out fine of i only use 1/4 throttle). It starts very easily and idles smoothly. I have cleaned the carbies, tried different jets, taken the exahust off and cleaned it, changed spark plugs, airfilter and done a general service but nothing has made any difference. This is very frustrating any suggestions?

Everything up to 1/4 throttle is perfect. Also when it dies its like it just cuts out instantly there is very little splutter etc. It is completely de restricted if that makes a difference.

If anyone knows a good mechanic in Melbourne please let me know.

o o


Last edited by DifferentStrokes on Mon Sep 28, 2009 10:28 pm; edited 1 time in total

Might be your regulator ?

Thanks for the replies so far. The carb intake boots are definitely on properly. I have heard that if it was the crank seal it wouldn't idle to well is this correct? How would i test the regulator and where can i find it?

i had a faulty regulator on my 28 but it was only highlighted when i kept blowing bulbs on high beam.
put a voltmeter on you battery...when running you should be getting about 14v's...my problem was that it occasionally peaked at 19-20 which blew the bulbs. see what yours does at quarter throttle.

however, mine was never serious enough to kill the engine !!?!?? just gave it a quick boost !!!

Dave.

Are the powervalve servo's opening with the throttle opening?
You can move them a little with engine shut off and then listen /look to see if they close when you switch key to on position- this won't tell you if they are working at 1/4 throttle but will tell you they 'work' at least.


You stated it has slowly happend over a month, electrical normal is intermitant or just plain on or off, but and air leak or mixture change can be slow to take effect -and get worse.
As you said you have checked the carby is nice and clean and jetting wouldn't have changed or need changing if you haven't modded it in any way.
Air lines to the 'x' pipe and 'y' pipe clear and not cracked?
Carb getting enough fuel after 1/4 throttle , possible starving and shutting off?
When it shuts off on you one time check the fuel bowls with a long flat blade screw driver to see if its empty


Just from personal experience did you take out air screws and clean them when you cleaned carby/ rest them?
it will only take the tinniest bit of dirt etc to block them

When it stops is it hard to start?

clean your pulser coils

have you checked the fuel filter in the tank and the tank breather. sounds like fuel starvation. have you checked the float valve's not sticking and the float heights?

Throttle position sensor shorting out at 1/4?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks to all who answered! The problem is gone now. The full story was i parked the bike for almost 5 months after having the problem for 6 months prior to that because i didn't have the time to fix it and the bike was too unreliable to go anywhere. After posting this tread i took the bike for another ride to better explain the symptoms of the problem it turns out it fix itself in the 5 months it was parked???? Its running better than is has ever done. SO believe it or not i now have a more modest problem and that is the cluch seems to slip over 8-9k because there is now too much power what can i do about this. The clutch has only done about 1000km. Its the dry clutch. Your comments will be much appreciated.

leave it another 5 months and the clutch will be fine too

have you tried backing the adjuster off a bit, may like a quick service after being sat for so long

In usual circumstances, a NSR dry clutch will easily handle the power without slipping, especially one with just 1000km of 'wear'. Have you seen how many plates are in the basket? Have you stripped the clutch plates out yet for inspection? Its very easy.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

If the bike's been sat that long, the plates are possibly a bit rusty. That will cause the clutch to slip.

You'll probably find that removing the plates and "roughing" the steels up with emery cloth will sort it out.

Don't over-tighten the pressure plate bolts on reassembly, as it's easy to break the posts off the clutch hub. I've seen plenty with only four posts!
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Andy.
NSR-WORLD.COM

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Andy wrote:If the bike's been sat that long, the plates are possibly a bit rusty. That will cause the clutch to slip.

You'll probably find that removing the plates and "roughing" the steels up with emery cloth will sort it out.

I did the above on my mc21 roughed them up a bt then sprayed all the plates and steels with brake and clutch cleaner. worked a treat.