700MM Blowing Belts

phazernut

phazernut

New member
Joined
Feb 9, 2007
Messages
38
Age
56
Location
Torbay, Newfoundland
700MM Blowing Belts and other question

Trying to help out a friend here. He has a 97 Mountain Max 700. It has stock gearing and a 1.25 X136 track. Used mostly on trails these days. He has bender tripple pipes on it. Sled has been clutched (Stock clutch with weights added by local dealer) and carbs adjusted for the pipes. Ever since he has had the sled even before the pipes it has a bad habbit of eating belts on any high speed run. He has tried several different belts with the same results. Just recently had his clutches checked for alignment and was told they are fine. Not sure of what RPM he is running but I think he said around 8800. Any help would be great.

Also ethonl based fuel has just arrived in his area. However 91 Octane does not have any. This summer he is going to freshen up the engine with a new set of rings. (he is at 90PSI per jug now) Wondering about drilling the head gasket and removing layers to bump the compersion ratio for higher octain fuel. he was also thinking about reeds but I'll point him to the reed mod thread instead.
 
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belt

Who told him it was aligned? I only ask because that is what it sounds like is wrong. alignment or center to center. :letitsnow
 
Unless you have a crazy clutch set up, alignment is what does this. Check the motor mounts also. I blew a belt on my MM and I couldn't believe how much the motor had moved.
 
belt

longshot, but maybe on of the bearings has siezed, and are causing drag, and eating belts. usually they disintegrate, but maybe check jackshaft,drive for problems. my 2 cents
 
It is very possible the clutches were aligned when the dealer checked them, but it is going out of alignment when on the gas. The motor doesn't flex the primary out of alignment until torque is introduced. Every single blowing belts issue I've seen has been caused from a broken motor mount, except in the case of the new XP's when they came out, which was caused by the chassis itself flexing out of alignment.
I would go over the motor mounts with a fine tooth comb, I'll bet you find a crack or one that's broke.
 
A friend of mine bought a 98 sx 700. He was blowing belts right away. I looked at it and saw that whoever owned it before added extra washers to the bolt that holds your secondary on so there was no side to side play. You have to have that play so that the secondary floats back and forth a bit. Thats another thing you can check for.
 
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