MTX eating belts

[Nikolai]

My MTX is eating belts It starts pulling out cords about every 3rd ride. It's been doing it for awhile. It's an 08 with a 150x15x2.5 and excell vector header. Otherwise pretty much stock.

clutch setup
green/white/green primary spring
stock 8FS weights with 17.2 rivets in every hole
pink secondary spring at 100*
stock 39 helix
19/40 gearing

There is no unusual belt residue or wear after riding(clutches look clean), no belt slipping. I had 20/40 gearing in it stock and switching to 19 helped cool the clutches a little. Both get pretty warm but I can keep my hands on them. I have pre-filter over all the vents and the headlight sealed so it's not snow getting on them. I tried lots of different clutch setups and the current one feels the best. My sled will hit 9,100 then drop to 8,800 under a load and hold it. Alignment is perfect and the primary is straight with the secondary. My belt squeals at idle after riding it(belt to tight) but the belt height is good and the distance between the sheaves is within specs.

Is it possible that the belt being a little to tight at idle could cause me to eat belts? This is getting annoying.

 

[akhammer]

My 09' has about 195 miles on it and I've gone through 1 belt. I have lots of belt dust on my clutches and don't get it. Did you have the same problem when it was stock?

 

[M5-]

How's your engine alignment?

M5

 

[Nikolai]

That was my first thought too but I ran a straight edge from the primary to the secondary and measured at the back and front of the driven sheave and they line up perfectly. Alignment should be spot on.

 

[dexter]

That was my first thought too but I ran a straight edge from the primary to the secondary and measured at the back and front of the driven sheave and they line up perfectly. Alignment should be spot on.

is the belt fraying on inside or outside, when mine was new i kept fraying belts on inside. my dealer checked alignment and said all was fine?? I removed one spacer from behind secondary and all was fine after.. Also check that motor mounts are tight and intack, If it twists from the load of the motor to much, belts won't last long. good luck.

 

[akhammer]

mine always frays on the inside.

 

[Nikolai]

is the belt fraying on inside or outside, when mine was new i kept fraying belts on inside. my dealer checked alignment and said all was fine?? I removed one spacer from behind secondary and all was fine after.. Also check that motor mounts are tight and intack, If it twists from the load of the motor to much, belts won't last long. good luck.

I've had them fray on both sides.

 

[khk]

wow the Yamaha belts are tough I have two mtx's and never had a problem in over 3,000 miles. sounds like something is coming out of alignment under load check engine mounts?

 

[Nikolai]

Motor mounts were torqued and re-torqued after rebuilding the sled. They should be fine.

Anyone know what the belt deflection is suppose to be? I'm thinking I can loosen the front two motor mounts and swing the motor up a little bit to get the clutches closer together and maybe get rid of the squeal that way instead of shimming the driven.


Edit: Just double checked C to C(a little over 10.5") and sheave offset(a little over .5") both of which are within specs.

 

[M5-]

Just off the top of my head I believe the center to center is 268.5 mm and the primary secondary offset is 15 mm. To get it right you'd be better off working in metric as thats how its spec'd.

M5

 

[Nikolai]

Manual has specs in inches too. C to C was 10.51-10.63 and offset was .53 to 6?. I'll triple check it again though when I get home from work.

 

[dexter]

try taking one shim out of the inside, i did all those offset checks too and mine seemed fine but burnt belts. removing one inside shim solved it. can't hurt to try as it worked for me. good luck

 

[M5-]

Manual has specs in inches too. C to C was 10.51-10.63 and offset was .53 to 6?. I'll triple check it again though when I get home from work.

I got the Canadian manual which I guess is all metric and as an added bonus you get half of it in french.

M5

 

[Nikolai]

I'll try the shim dexter, at this point I'm open to anything.

 

[ehna]

Nikolai,

I'm also burning belts (4 up to now this year)

Same problem as you, pulling cords!

Not sure what Dexter means by "try taking one shim out of the inside" ???

Errol

 

[Nikolai]

The secondary has shims that go on the jackshaft before the clutch goes on. I'm assuming he means remove a shim so the secondary can move closer towards the engine.

 

[ehna]

Thanks! Will try that and see!

 

[dexter]

yes, one on the inside so it goes in closer to the engine. start with a new belt, and try to break in the belt.
Let me know if it helps.

 

[Beels]

Try taking all the shims out and let it float. It won't hurt anything. Eliminates that issue altogether.

 

[Nikolai]

The Nytros already float the secondary. Going to throw it on the stand tonight and see if the motor is moving at all under power. I did take another shim so I'll see if it helps.