Here goes......I have a 1992 Yamaha Exciter 570 II LE that suddenly started bogging horribly. The carbs were cleaned an re-jetted for a Bender single pipe that was put on. The sled ran great for a couple weeks. I was out riding the snowmobile last week, slowed to cross a road, gave then sled some gas and BOG....the snowmobile started bogging. Tried a new belt and plugs, still bogged. I got the sled home, checked the compression and I had 120+/120+ in the two cyliders. Good compression. I found a seized carrier idler wheel on the suspension that was worn down into the aluminum of the wheel. I changed the wheel and put new bearings on both wheels on either side. The sled still bogged. Upon further inspection, I noticed the secondary clutch had a ton of play in it. I inspected further and found that the jackshaft bearing had gone out, beyond seizing to nothing left and the jackshaft bearing housing was cracked and ruined. The jackshaft bearing housing and bearing were replaced. The jackshaft was still in good shape so just the bearing and housing were replaced. The sled STILL bogs! The sled starts great, idles perfect and revs up awesome -> with belt off it revs up awesome. The primary clutch seems to operate great, compressing and decompressing with the rpms of the motor. I can get on the sled and drive to like 10-15 MPH starting out with no problems but as soon as I get on the throttle a bit, she bogs down and if I crack the throttle open, the sled really slows down and barely moves. As soon as I let up the throttle, right back to perfect idle and a slow cruise. TORS system is disconnected and hooked into itself just like everyone does it. I think it is a secondary clutch issue. The spring is fine, but is it possible that when the jackshaft bearing went out and seized for a bit, the spring slipped out of one of the holes into a different one or into one of the 3 different settings in the secondary? Which setting is the average normal setting on the inside of the secondary, A....B....or C??? The belt also seems to sit like 1/8 inch into the sheaves on the secondary now, is that too far in when just sitting still? This problem is really frustrating and Winter is disappearing quickly, does anyone have ANY ideas??? Thank you very much for any help!!
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rx1jim
New member
Thetop of the belt should be flush with the top of the secondary sheaves. How much play does the moveable sheave in the secondary have on the shaft?
You could also try to flip up the enrichener lever while you are applying the throttle. If the enrichener helps, then the problem is in the carbs. When you cleaned them, did you remove and inspect the openingings in the jets to make sure they were open?
Have you checked the center to center distance of the primary clutch and the jackshaft?
You could also try to flip up the enrichener lever while you are applying the throttle. If the enrichener helps, then the problem is in the carbs. When you cleaned them, did you remove and inspect the openingings in the jets to make sure they were open?
Have you checked the center to center distance of the primary clutch and the jackshaft?
no1chevyboy
New member
check carb sync,your belt should sit to the top of the secondary sheeves,if belt is brand new and right then check secondary
The carbs are in great shape. I tried the choke as you said several times and it made the sled want to die. The moveable sheave, being the back sheave I assume, moves foward and backwards probably over 2 inches...or maybe more, semi-easily. Could it be a preloading of the secondary clutch spring issue? Is it possible the spirng jumped and lost its loading when the bearing went out in the jackshaft? The belt is around 1/8 of an inch below the top of the sheaves, that is too low. Probably because the loading of the clutch spring is gone allowing the belt to settle too low. Possible??
One more thing, the sled seems to bog worse in looser packed snow. It seems to get up and go on roads and hard pack better. Any ideas??
Everything I'm reading leads me to believe you have an issue with your secondary clutch. The spring might be broken, something is causing the sheaves to bind, the buttons on your helix might be shot. Get that thing taken apart and check it all over and I bet something is a little screwed up in there.
Swuff
New member
i know it a long time ago but the rollers on the primary may be worn... mine were missing and took a lobg time to tracm this issue out.... changer em and omg what a new machine