miles> > Problem: Intermittent Missing at high speed/high rpm. Started 100
Never> > from Moab continued till today. Most typically the engine misses on a > > series of long uphill grades at interstate speeds, very irritating.
entrance.> > misses around town or on the trail. So far I addressed the problem by: > > Opening the gas cap at speed while engine was missing; didn't help. > > Cleaned air filter. Took off float bowl then blew out fuel line
have> > Installed new vacuum line from carb to petcock. Checked coil for > > resistance then had it checked for spark; all read fine. Spark plug has > > less than 2k. > > Today I took the bike for a ride engine commenced to missing. Though > > the tank was full I decided to try something, I switched to reserve; the > > engine stopped missing immediately and ran great until.....I moved the > > lever back down to regular open position; in a mile or two it started > > missing. When I moved back to reserve it again ran fine. Repeated > > experiment with same results. As a final test I stayed at the reserve > > position and ran the bike at 80-90mph for 40 miles on a stretch of I 25 > > that climbs about 1200' from Pueblo to Colorado Springs. Exactly the > > situation where the problem would usually manifest itself. The engine > > didn't miss a beat. > > .......I've installed Skip F's petcock mod but since the problem started > > before the mod was added, it doesn't look like it's a factor. I don't
Bogdan, I`d try a rebuild kit on the petcock, you might be sucking a little air through the petcock when in the main position. I hate to tell you this, but I would first pull the petcock down, just enough to get the line to the mod pick-up through the hole, then disconnect it from the petcock. Then see if you can blow through the main copper tube, with valve in the main position and vacuum applied to the vacuum nipple. If the main position chambers are clear, take the thing apart. You`re right, as long as the inlet screen to the mod is in fuel, it`s no different than if it wasn`t there. Let me know what you find. Skip> > much experience with petcocks. (I do have a dog.) Has anyone heard of > > something like this? Is the main line dirty? Can't see how; it's always > > had a filter on it. Is it one of the O rings or a gasket? Do I need a > > rebuild kit? Any comments/advice appreciated. Bogdan >