Carbie fouling a spark plug...

[SqDancerLynn1]

Just a thought ? Have you tried to sync the carbs ????

[Nightmare]

I've synced my carbs, oh yeah, forgot to mention i also tried cleaning the gas cap (vent holes)... The ONLY thing that is left to make sense for my bike at least is: I had a problem with the petcock (leaking fuel through the vacume line), replaced the petcock with a new unit...

As a result it MIGHT be possible that: I have carbon build up in the #2 cylinder causing a higher then normal compression reading (last reading was 120 or 130psi, which is normal) BUT, maybe there is also carbon build up (or a burned valve) on the intake valve that is causing lower compression readings (which balances out the higher compression by the carbon build up in the chamber). And its possible that the stuck intake valve is somehow pulling more fuel in..? I know this is a long shot but I can't think of anything else that will cause this problem.

I'm off to pull the carbs off the bike again (maybe through some combustion chamber cleaner in the #2 for "the fun of it") going to quadruple check the #2 carb for plugged passageways and going to try swapping the float/pin and needle/valves with another carb.

[Nightmare]

Swapped the remaining carb parts and recleaned the air/fuel passages, guess we'll see, one other side note, i checked my notes and noticed that my #2 intake valve is out of spec (.102mm instead of .08mm) is it possible that .02mm is going to make THAT big of a difference?

[49er]

Swapped the remaining carb parts and recleaned the air/fuel passages, guess we'll see, one other side note, i checked my notes and noticed that my #2 intake valve is out of spec (.102mm instead of .08mm) is it possible that .02mm is going to make THAT big of a difference?

No. The extra clearance will retard the valve timing slightly and make the engine a little noisyer.

[tfb]

Well, the new jet needle has arrived and I'm about to waltz back out into the shed and spend the next few hours reassembling it all.

Wish me luck! 8-[

[Steve]

I WISH YOU LUCK \\/






May most of it be good. 8-[


.

[tfb]

G'day all,

Well, I think it's sorted! \\/

Since the last unsuccessful test ride and today's wonderful trouble-free run, here are the things I tweaked:

1. New jet needle in carbie #2. The more I looked at the old one, the more I realised it was positively dodgy.
2. Cleaned minute traces of rust sediment out of the needle valve on carbie #2. I cannot see how this could have caused the plug-fouling problem to the extent that I experienced, but you never know.
3. Fully carbie sync. with the mercury vacuum gauges.
4. Checked and fiddled with #2 spark-plug lead.

It can't have been the plug-lead, because otherwise I would have had mis-firing from the moment the bike started, instead of the progressive worsening over a 20-minute ride.

It just *has* to have been that corroded carbie needle. What caused it to corrode is a real mystery; all the other needles are fine. Whatever it was, it reacted with the needle's metal, and left a black residue that could only be removed by abrasion. Go figure.

Thanks all for your encouragement and help.

Cheers,
Mike.

[chef1366]

Good one on ya M8.
Happy endings are great. Now we have to deal with this guy that hates his bike.http://www.thegsresources.com/_forum...=109579&page=3