Open throttle sputter, again

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May 28, 2006 | 01:40 AM

zenwarrior

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Cruiser

Joined: Apr 2006

Posts: 139

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Open throttle sputter, again

I have the Mikune carb, had sputter/miss problems a couple weeks ago, I had put on new pipes. Put in a better set of plugs, it has been running fine, still a little rich, I think, as the plugs are dark and tonight I tried the 'roll off' technique and when I cut back from full throttle, it did surge ahead, which means running rich according to Mikuni manual. The problem again is, as I opened it again to throttle up, it started spurttering again. I cut it back and opened it again, it worked through it for a bit, then started sputtering again. I cut down on the throttle, runs ok at mid rpm. I got back and checked the plugs, they actually looked better than they had before. Also, it was getting cold outside, after sundown, I was told Mikuni's dont do well in cold temps?????? Now, I had run a couple tanks of mid grade gas to see how it would run, save a few bucks on gas? Well, I started to get ignition fire after I shut it off, so today I switched back to premium, that problem quit, but having the old sputter at open throttle again. Question is, the main jet controls fuel mix from 3/4 to full throttle and the main jet needle controls fuel mix from 1/4 to 3/4, right? So, I should try lowering the main needle, or try a different size? Or is it possibly another problem alltogether? Am I safe in still running her as long as I dont push it up too high on the throttle, until I can order another needle (I dont usually run full open, anyway, just had the opportunity to try a test on the open highway.) Any help would be appreciated, dont want to mess anything up by continuing to run her,but dont want to miss the best weather we have had yet. Besides, she is my only transportation right now.
hanks,
zen

May 29, 2006 | 12:05 AM