idea's jd & cm please

i swapped to yz timing & left the bike standard otherwise back in early August. the next day it was wonderful & went like snot, revving out beautifully.

did my green laning a week later in the isle of man & because you can't help revving it out i know it was still good.

came home, prepped it for a race (went from 13/50 to 13/48) & had the troubles i reported 14 days ago.

to remind you again; knocking, very hot on my legs, poor pull in top. knocking cured with fresh fuel & nothing else. short shifting to get along on third lap & stop to find my little bodge to block the the tube with the jet in it had come off.

i put the whole thing down to running lean due to the air bleeding in at this point.

i blocked it off with bungs that actually stay on this time jetted up to 172 from 168, new rings, gaskets, waterpump seals & all internals look lovely.

went out to play yesterday. same again. if it's obvious JD & CM let me know.

while i'm here, i bent the DVP needle in my suitcase, it's only a teeny bit bent but it shouldn't make a difference should it?

with dell orto's the needle was always wedged against one edge anyway.

so what do you think has happened?



Do not use a bent needle in your carberator you are only asking for trouble.

As to your bikes poor running from your discription is still sounds like a air leak screwing up the mixture.

Did you remove the accelerator pump bowl and maybe loose one of the two "O" rings between the accelerator bowl and the float bowl-- this will cause a leak?? Is your accelerator pump diaphram in upside down?? would cause poor to no accelerator pump performance?? If you have a 99 or 98 bike with a remote Hot Start button make sure when the button is closed that it does not leak--check it with vacuum or suction it should not leak?? The Carb top is another candidate for a leak?? If you removed the octopus make sure the ports are sealed off.

With YZ timing I would not run less than a 48 pilot jet.

Cam timing checkout ok with all the timing marks lined up. Try a CDI off another bike??

Carb activation shaft to slide attachment set up per the instructions in the TECHNICAL section???

All I can think of at the moment


[This message has been edited by Clark Mason (edited 09-25-2000).]

[This message has been edited by Clark Mason (edited 09-25-2000).]


I thought you were using the DXM. There is a screen on my carb just above the float needle. Make sure none of the fuel screens are clogged there and in the tank. Maybe check the float level and operation. Vacuum leaks as Clark said, but I would think the idle would also be fast if it were a problem. Clogged radiator? Could this be overheating? Is there any way to put gaskets on incorrectly blocking passages? Water pump working ok? (Unlikely possibilities, but just throwing out ideas)


thank you gentleman!

like you lads i'm hoping that it's something i've touched & so i can narrow it down. from your thoughts the air leak seems the obvious one & i will go for the hot start button which is now straight again having been bent in my only fall of the holiday in the rain. this was on the last day.

the radiator was a little clogged but not from the off.

the needle will be thrown away unceremoniously!

will have a crack at some of these soon & will keep you posted.


well i found out what it was.

the hot start button which i had relocated to the underside of the handlebars on the throttle side had hit a rock in an accident on the last day of my holiday. my friend picked it up once he had dropped me off at the airport & i later prepped it for the aformentioned race.

what i think happened is that it wasn't a poor seal & it WAS going back into place but because the rod was slightly crooked it would only pass air in certain positions.

i must have stalled it in the race, the button turned a little & the rest as they say is history.

i'm so pleased with the chugability of the bike that i've gone from 13/50 then 13/48; this weekend it will be back to 14/50 which is standard gearing. i was able to buy the clamp piece for my Magura juice clutch at a hefty £18 ($29) & so that'll be back on & i finally bought a new front tyre after 1'500 miles on the old one. well i do believe in getting good value doncha know!

if i get one good ride out of this-without glitches-i will try the variable timing camwheels (vtc)in the 4-week gap i have after this weekend.

thanks to clark mason.


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