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Showing results for tags 'jolts'.
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Hello all, Thanks in advance for your help. I've got an '84 XVZ1200. I've owned it about 3 years. This season, it started doing something weird the 3rd or 4th time I had it out. As a result, I haven't been able to ride much this year. It's taken me a few rides to get things narrowed down, as it was fairly intermittent. When: Under light acceleration, no problems. Under moderate acceleration, it happens occasionally in 1st and 2nd. Under heavy acceleration, it happens repeatedly during acceleration through 3rd gear. I have eventually narrowed it down to a position of the throttle. "What" happens: I describe it as a lurch. Although, the lurch is the result of the engine dying for a split second, followed by a quick rebound when it starts going again. When I say the engine dies, I mean all 4 cylinders loose power (not a gradual power lag). My initial guess was fuel starvation, perhaps from gummed up jets, etc in the carb. But, after running 2 tanks with half a can of Sea Foam each, there was no change whatsoever. (I understand Sea Foam won't fix everything for sure... it may well be clogged.) I then started to rule this out because of discovering the quick, repeated jolts under hard acceleration later on (see below for "speed"). As a result, I started leaning towards an ignition problem. Its as if the coil(s) run out of spark. What strikes me as weird is that if I run the RPM's up slowly, I can get it to redline without a problem... the engine runs normal all the way up. So, it seems as if ignition is working OK under load (at high RPM). So, this brings me back to a fuel problem. Are there accelerator pumps in these carbs that might be failing (I assume not)? I'm still surprised that the fuel could "recover" if there is a momentary starvation so quickly with the speed of repeated jolts. To give you an idea of the "speed" of these jolts: If I rail on the throttle, I would guess it gets as "violent" as 4 times per second in the 2000-5000 RPM range, and weaning off to 1 time per second nearing redline. Does anyone have any idea what this could be? Many thanks in advance for your help! Regards, Scott