Quote:
Originally Posted by parrycm
Some context first - It ran very rich and chewed fuel but I ran it like that on my ride up to the mid-Ohio mini raid because there wasn't time to return it to stock. Halfway back to Texas, it started a misfire (like a stutter) on cylinder 1 especially around 4000 revs and on steady throttle. On acceleration it seemed to go away and lessened at higher revs.
...I stopped at a Vintage Car Workshop in the middle of nowhere and drilled some holes in the RH side of the airbox. That certainly reduced the richness as it wasn't blowing as much smoke now but it still misfired.
I have a spare set of bone stock Mikunis and so finally I fitted those but only after replacing all the o-rings which had hardened up which caused them to leak like a sieve. Voila! Based on a test run, all is now OK.
Any ideas?
|
My best guess would be worn needle jets (if the Dynojet kit didn't require drilling the slides). The Mikuni design lets the needle and jet come in contact (especially with worn slides) and the needle jets tend to go out of round and 'leak' a bit too much fuel around 4000 rpm.
Some of the Dynojet kits require enlarging the vacuum port in the slides and that could cause the slide to rise too rapidly.
If you examine the needle jets and they're good (not oval or having a shiny stripe inside) AND you've drilled the slides, then try lowering the needle one notch to hold off the taper start on the needles.
Let us know what you find!
Jim
