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
