Alright this has been an on going issue for months now, work on it as parts come in and we have been making progress. Let me give you all the details and where we stand up till today.
2006 Arctic Cat DVX 400
Full DG exhaust
New DID Cam chain
stage 2 jet kit, currently set at the 146 jet
UNI filter(with lid removed)
Hi-Rev box, not sure of the brand bought it like that
13t Renthal sprocket
Ok here is the history:
When I bought the bike it ran pretty rough and had a slight tick/knock in the engine. Replaced the timing chain with a D.I.D. chain, had the shims redone and all of the internals set/fixed/adjusted. Engine ran much much better. Started better, idled better, ran better. Every now and then it would either stall or backfire and then stall(specifically at low speed in 1st or 2nd gears, usually if I was just putting around). One day it backfired and shut off, couldn't restart it to save my life. Took it to my mechanic buddy, who took the carb apart and realized the plastic sleeve that held the metering rod down(it has 4 clip like nubs around it, was missing 2 nubs) was broken, so he JB welded it to see if that was the issue and it was. Quad ran better then ever before, but would still stall here and there and again usually in low gears at low speed. So I decided to order all new internals for the carb.
New parts arrive, mechanic rebuilds the carb, and we test it over and over again until we get the proper jet in there(if you would tap the throttle if would eventually stall or backfire, but not nearly as much). We did this until I was unable to force it to stall/backfire which led us to believe it was now jetted prooperly and running the best it had ever ran. Once it was all together and running correctly, we realized that the long(maybe 4") main spring wasn't replaced with the new one. So we decided to replace the stock one with the brand new one that I ordered. Put it all back together with the new spring, it started up perfectly, idled perfectly, but when you gave it gas it would rev fin until about the middle of the gear then start backfiring, sputtering, popping, etc... OK so we put the old spring in, same thing. Keep in mind all was fine until we swapped springs, so now it would do it regardless of what spring was in. We took the entire carb apart, cleaned everything, same deal. We noticed around the same time when the fan would come on, and you'd shut the key off the fan would stay running for about 2-3 seconds and then shut off, and while it was staying on the headlight would light on its own, then shut off when the fan did. Thought this was odd, but maybe it was normal and we just never noticed it before. Video is posted at the bottom of this happening. Regardless, the fan would always shut off the second the key was turned off, now it has this 2-3 second delay. So we thought something electrical, so we tried to bypass the throttle positioning sensor, just trying to see if there was any difference, NONE. Next was to replace the CDI with the stock one, same deal. Then we tried doing the reverse rev limiter bypass, no luck. Still sputters and backfires, just goes fast as hell in reverse. The only thing we haven't messed with is the shift positioning sensor.
Has anyone had this issue, if so had a fix, or does anyone have any thoughts? Now we are thinking maybe the TPS or the SPS are bad? Could it be a short elsewhere? Does it sound like a bad coil? Any suggestions on where we should go from here?
Thanks for reading my novel.