Sucking air would make the sled lean and this would show on a plug reading as well as a hot motor...ask the prez. 1776 is running very rich I believe. The motor thinks it may be running lean,ie: electrical problem, so it adds fuel to compensate.
My REV had a hole in the rubber boots on the intake (is that the bellows? that the guy on HCS was referring to?) and I had the same performance issues last year. My machine ran great at high RPMs and lousy at idle and midrange. We adjusted the idle to make it work ok.
The Pez replaced them for me and it worked fine. It actually had a hole on the bottom, where you just couldn't see it without disasembling it.
I had the idle turned up so high that when it was fixed it the clutch started to engage when we started it up.
What about just a crappy gasket seal on the intake? Could he be sucking air somehow without a hole?
#1776's XC is not running in "safe" mode as far as I can tell. That mode only allows revs up to about 5-6K or so, just enough to move forward. But his sled will rev up and go 70+mph if given the time to do so. My XC ran in "safe" mode not too long ago when the temp sensor went off due to low snow in the local trails so I remember clearly what this condition runs like.
The other thing that puzzles me is that he says the performance deteriorates as the day goes on. temp saturation would explain that but it seems that it takes too long for that to be the case. I was convinced on the last ride that it was water ingestion (mine had similar performance I think because I was breaking trail) but again his got worse as the day wore on where the conditions actually improved for us (and mine cleared once on groomed trails).
All the info and replies where on HCS. I did a search and it came up (CDI). Electrical makes sense since you've looked at everything else. If something electrical was failing or intermittent, that would cause your motor to "retard" timing and run like it's been running.
Hey Craig, thanks for the info.....do you have a link to the info you found on the CDI ground wire and temp sensor? The temp sensor was replaced by polaris, it has the yellow tag from the dealer, they had a recall on them I guess from what #5 told me.
I am going to reply to the post you started on HCS
Thanks again! 1776
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#1776 - 2007 NETRA Hare Scrambles BVet Champion, 2006 NETRA Hare Scrambles BVet Championship - 5th Place, KTM 250 EXC, Polaris 800 XCSP, Ski-Doo Formula 500.
I did some research on a possible cause to your sled problem, I found alot of people claiming the CDI ground wire located on the right side of carb, by the reed cage could be broken/intermintent.
Check temp sensor, bad sensor will retard the timing
