97 VMAX SX 700 Drive Belt Slipping

4

4wealn

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Joined
Feb 11, 2015
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129
Location
Ontario, Canada
So last week I was joy riding and could constantly smell rubber when I gave it throttle from a stop. It had not done that before. I looked at the belt and it looked glazed on the sides of it. I had a brand new Yamaha belt so I swapped it out. The one that was on the sled when I bought it from a buddy was an 8DU or CU, I cannot remember right now but the one that is supposed to be on there is an 8CH which is the one I put on there. I took it out today and I can hear the belt slipping. It seems to be riding the allowed 2mm in the secondary sheave, but it is audible slipping from a stop.
Can somebody please give me some guidance. Do I need to clean the surface where the belt sits in the primary sheave as it looks shiny. On slow acceleration when the centrifical engages it slips and really smells.

Thanks in advance guys.
 
i think you should clean your clutches out and scuff up the surfaces. sounds like they are full of belt dust at minimum and could possibly use a new primary spring as that one is probably weak from age.
 
OK, so I was out at the sled today. I took off the belt and cleaned up the clutches and the sheave surfaces. They were not that bad at all. I scrubbed them down with a green scotch bright pad and wiped them down after with some rubbing alcohol. I also looked at the rollers and there were no flat spots. The one thing I did notice which I think is normal was the bolt going through the rollers, I was able to move the bolt back and forth. Looked like it needed tightening, but all three were like that. The lock nut was in all the way. I think it is like that so the roller will roll.
I sprayed some brake clean in and around the primary spring, but it was not that dirty in there. The movement in and out was good and did not stick at all. I looked at the drive belt that was on the sled when I bought it and it is within spec for width but is about a quarter inch longer than it states in the manual that I have. It is an 8DN-17641-00 which when I looked it up was for a viper. The 8DN belt slips on take off from a stand still. I can smell the rubber. If I feather the throttle a couple times then it is not that bad. I do have the belt that is supposed to be on the sled. It is an 8CH-17641-00. I had that one on the other day, it is within spec for length of the belt at 44.6" and of coarse it is within spec for width as it is brand new. I did not try that one today as I wanted to go for a ride with my daughter. Sled ran great other than the slippage. The 8DN you can only smell slip, the 8CH you can hear and eventually smell.
Put 40 miles on it today, other than the belt issue, it ran great.
Any ideas with this more info as to how I can tackle this.

Thank you in advance guys.
 
4wealn said:
That I am not sure about. I will look tomorrow. If I am, should I take one out. Also should I be using the 8CH belt instead of the 8DN belt?
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Use whatever belt yamaha recommend you to use.
Behind your secondary you should see three bolts with each one washer. Removing the three washers will open the secondary clutch a bit and loosen the belt. Adding washers closes the secondary a bit causing the belt to ride higher in the secondary and tighter around the primary.
 

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Thanks Vincent. I did not have a chance to get out to my sled to day as the weather was terrible. I will look this weekend.
 
Vincent said:
Use whatever belt yamaha recommend you to use.
Behind your secondary you should see three bolts with each one washer. Removing the three washers will open the secondary clutch a bit and loosen the belt. Adding washers closes the secondary a bit causing the belt to ride higher in the secondary and tighter around the primary.
Click to expand...

I had a chance to look into this a bit deeper. I am currently running 1 washer behind each bolt. The 8DN belt rides about 0-.1mm above the secondary, when I put the 8CH belt on it is about 2-2.5mm above the secondary. If I have the correct values, mine should be 0-2 mm below the secondary. In this situation, for me to use the 8CH belt (which is the one listed for my sled), I would have to remove a shim to open up the sheave a bit more. Correct?
I also took the 6 10mm bolts off the primary and cleaned up the shaft and measured the primary spring. I measured 79.05mm and my manual says 81mm, so I think I should order another primary spring. Everything else looked good. All the weights looked good and moved freely, along with the rollers. There are no flat spots and everything moves freely.

So, I think I will order 3 new bolts and change those along with the primary spring. This will allow my belt to ride deeper in the sheave, and give me the right resting spring length for the primary.
I did measure the center to center for the primary to the secondary. It calls for 10.57 plus or minus inches and I was measuring about 10.5, so that seems to fall in the range.

Any other suggestions. Can someone also check the tolerances that I have listed to make sure they are they same for a 97 vx700sxa.

Thank you
 
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ya know you can always loosen the motor mounts and move it forward and backwards to make the belt work as needed. seems lots of people get all hung up on the center to center measurement. in a perfect world where there is no belt length variation. belts are hardly ever as advertised and lets not forget if a belt happens to stretch the center to center distance means nothing. keep the belt sitting flush in the secondary and move the motor if needed to get proper deflection.
 
OK, so I was out today playing around with the sled. I purchased a new primary spring as per the manual. It is a W-S-W spring. I put that in and scotch brite the sheaves. I also purchased new secondary sheave adjustment screws and put those in. When I removed the ones that were in there they were about .65mm shorter than they should have been. After replacing them, the 8CH belt fit in nice and sat around .6mm below the sheave which is right in spec as it should be 0-2mm below the sheave.
I fired it up and it looks like engagement is around 3600 where as before the spring change it was around 4000. It all seemed alright but I could still smell some rubber on initial take off. What the heck is going on. Has anybody else experienced this. Please help, I am getting pretty frustrated now.

Thank you in advance.
 
if it were me i'd buy a different brand belt. I personally think these Yamaha belts are junk.all I ever read on this site is buy oem. oem is BS. Yamaha doesn't make these belts it like every other deal of whoever is low bidder. spend a little more and get what you pay for.
 
Certainly nothing wrong with considering other options on the subject of drive belts. Myself I only run the yamaha belts and each one gets 2500+kms of hard use / very aggressive riding each season with zero issues. But I do proper maintainence on my clutchs, driveline and chassis.
 
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My comment was not ment twards you. I was only sharing my experiences with oem belts. Clearly you have done your homework and have put the effort in trouble shooting your issue. Wish I could be of more help to you.
 
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whats your sec. setting at? it may be too low, tighten it up to 70*. also if your going to run the 8dn belt ,you must put more weight in the tips of your primary weights, 8dn's are a harder compound belt and require more preasure and force !
 
Maim said:
that should have an 8dn belt on it. problem could be the belt compound is too soft.
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When I bought it there was an 8DN belt on it, it should be an 8CH belt. I didn't realise it was an 8DN so when I bought my spare I bought the replacement for the sled which is an 8CH. Should I buy another belt but an 8DN this time. What about what yammy said about the pressure. All I know is when I got the sled (used of coarse) there was no slip in the belt and it was running with an 8DN.
Maybe I should just get a new 8DN and see what happens.
 
yammy said:
whats your sec. setting at? it may be too low, tighten it up to 70*. also if your going to run the 8dn belt ,you must put more weight in the tips of your primary weights, 8dn's are a harder compound belt and require more preasure and force !
Click to expand...

As far as I know, my secondary is stock. I know there is a green spring in there which is what the manual says, but I am not sure what degree it is at.
 
as far as i know, all tripple yamahas used an 8dn belt from factory. i know the twins used a softer belt that when i used one on a tripple to get home would cause issues but was better than walking.
 
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