01' XC 500 bogging off idle & surging on top end at WOT
I'm having a problem with my 01' XC 500 Edge (NOT the VES SP engine)
It pull starts & idles well (but not super strong, though most carb'd sleds don't in my experiance), and if you half choke it at idle it dies immediately so I assume it isn't too lean (I also played with the pilot fuel screw anywhere between the factory setting of 1.5 turns out, too 1 turn out & 2 turns out) but If you pin the throttle pulling out at idle it just bogs & shuts off.
If you bring it up to 2000 rpm & pin it, it stumbles then backfires through the exhaust, & then takes off when the rpms get up over 3000. If you ease on to the throttle "normally" when the clutch engages it pulls out pretty well & takes of good as the engine climbs up into the midrange where it runs very good if not fantastic.
Running over 3000 RPM at between 1/8-3/4 throttle in the snow (6-8"s), it continues to run fantastic till 77-8000 rpm where you'll notice a very slight REV limiter type "surge" OR you go to WOT - then it acts as if it's barely able to maintain the speed you were at plus develops a surge which feels like it's banging off some kind of REV limiter (which I don't think it has AND I'm pretty sure this engine is good for 8200 + rpm anyways)
Running half choke seemed to help a tiny bit with the bottom end hard take off bog, but definitely didn't fix it AND running half choke did nothing for the topend power loss & surge plus making the normally great mid range sound dull & un-responsive.
Another oddity is the symptoms at WOT + 8000 rpm changes when the engines loaded - in the yard in 8"s of snow it's very evident, but when on the super hard pack dirt road snow, the surge goes away almost completely and it pulls up through the gearing much better. But even on the road if you let up to 3/4 throttle it pulls harder, smoother, and faster.
I thought maybe the load on the engine wasn't high enough for it's RPM power range, so I knocked the secondary spring down to the first hole. After doing that, it does exactly the same thing as it did before, but it does it 200 rpm lower at WOT. Plus I later read the this engine is supposed to operate at 8000rpm +/- 200 and is capable of over 8400 if you push it hard.
I'm thinking CDI/timing at this point, but it's not possible to test a CDI as far as I know AND it's so expensive to replace them. As for timing, I don't know the first thing about checking that on these engines. And if it was base timing, why would it be acting up everywher but 3000-7700 at between 1/8-3-4 throttle?
Sooooooooo - any ideas?
1988 Polaris Indy 400 - sold
1996 Polaris Indy 500 - sold
01' XC 700 SP - YeeHaw!!!
01' XC 500 - currently having a couple issues.