blown belt at 110mph

j2hizzo

j2hizzo

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Oct 23, 2008
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southern maine
anyone have trouble with blowing belts at high speed? I blew a high quality belt two times at over 100mph. I ran fine at 3/4 throttle but when I went to give it a last little pinch it blew both times. I would say a thousand feet after I gave it the last pinch is when both the belts blew. Im thinking clutch problems?
 
I am assuming when you say high quality belt you mean non-yamaha? Always use Yamaha belts. This is most likely your problem but it could be a few other things also.
 
ryanryan said:
I am assuming when you say high quality belt you mean non-yamaha? Always use Yamaha belts. This is most likely your problem but it could be a few other things also.
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I agree ,stick with those Yamaha belts...pays off in the long run!
 
not a broken motor mount, yamaha belt, and im having smiths power sports in fort fairfield maine do the clutches. hope it works
 
You clutch alignment is off. Better get that fixed.

It's nice to see someone actually admit to blowing a Yammie belt. They are not as invincible as everybody thinks.

I'm now using Ultimax 3s because they slip way less than the hard Yammie belts and I have only blown one, and guess what... my alignment was off.

Put an Ultimax 3 on your sled and watch your RPMs drop 200 RPM. What does that tell you???

Align those clutches and ride!!!
 
Exciterfan said:
You clutch alignment is off. Better get that fixed.

It's nice to see someone actually admit to blowing a Yammie belt. They are not as invincible as everybody thinks.

I'm now using Ultimax 3s because they slip way less than the hard Yammie belts and I have only blown one, and guess what... my alignment was off.

Put an Ultimax 3 on your sled and watch your RPMs drop 200 RPM. What does that tell you???

Align those clutches and ride!!!
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YOUR WRONG DUDE, THEY ARE INVINCIBLE. WHAT BELT COULD TAKE MIS ALIGMENT. THAT YAMAHA 8DN BUILT HAS PROBLEY GONE FASTER INECSESS OF 150 + mph ON SLEDS WITH 450 HP TURBOED CHARGED THAN I WOULD SAY ANY AFTERMARKET BELT. NEVER MISSED A BEAT. 3:16 (yammie tony)
 
Have heard of a number of Yammi belts blowwing this year. Wonder if they had a bad run ? Hope not, I just bought one :o|

The reason for the RMPs going down, is because of the softer compound of the Ultimax belts. Atleast that is the way I understand it.
 
IF YOUR CLUTCHES ARE 100 % CORRECT, A 8DN BELT WILL LAST YEARS. MATTER OF FACT, I HAVE USED ONE 8DN BELT BETWEEN TWO SRX,s. AND ONE OF THEM IS MY ICE/ GRASS DRAGER. 3:16 (yammie tony)
 
Exciterfan said:
Put an Ultimax 3 on your sled and watch your RPMs drop 200 RPM. What does that tell you???
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That they are softer and grip the sheaves more than an 8DN when using the same clutch setup. Apply more weight to the 8DN belt and it will grip just as hard. You can't compare the same clutch setup to two different compound belts.
 
I totally agree shortstop. But I also think there might be slippage with the 8DN. Which you can throw more weight at it in the Primary to reduce it.

If you check out the Hartman web site, he ( a Yamaha expert) would agree.

After aligning my clutches I have witnessed very little wear on my Ultimax 3 belts. They seem to work well.

They are both good belts. I just think it is unfair of people to bash one brand when in reality it was most often poor maintenance on their part not the quality of the belt.
 
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the last time I used an Ultimax Belt,it cost me the price of the belt and a new speedo cable and a dented in footwell.They just don't cut it.Never...ever..ever blew or even shredded a OEM belt in all the years I had ridden Yamaha sleds.That has got to tell you something.Actually runing one OEM belt for 2 season's now and the wear is good.They are tough belts,and as for slipping..they do get warm and I am sure they are gripping just fine.I raised the ski's totally on my SXR600 on Sunday for 80 feet..so that belt sure is grabbing. ;)!
 
This year and last, I spent 2 new ultimax 3 belts at 104, this past summer I had my clutches aligned to solve my problem, it did not work.
 
If its slipping the clutches should be hot.



Exciterfan said:
I totally agree shortstop. But I also think there might be slippage with the 8DN. Which you can throw more weight at it in the Primary to reduce it.

If you check out the Hartman web site, he ( a Yamaha expert) would agree.

After aligning my clutches I have witnessed very little wear on my Ultimax 3 belts. They seem to work well.

They are both good belts. I just think it is unfair of people to bash one brand when in reality it was most often poor maintenance on their part not the quality of the belt.
Click to expand...
 
Check to make sure the sheaves in the primary clutch are not warped. I couldn't make it more than 100 miles on a belt. Blew one well over 100 mph, wasn't good. checked everything and found that my fixed sheave was warped badly. replaced it and have been fine ever since.
 
Clutches have to be tuned to match the entire setup no matter which belt you are using. Heat is what usually destroys belts. Slippage or twisting is what usually creates heat. Many things can contribute to slippage and twisting. Alignment, offset, side pressure (not enough), binding bushings, weak or broken springs are just a few of these things. The rubber in the 8DN belt has a higher durometer reading which means it is a harder rubber compound. This makes it more durable, but not as sticky which means that it requires more side pressure to avoid slippage.

In your case, I would expect that the finish side pressure in the secondary is not enough to avoid slippage. That is if all else is well. You should see black marks well down into the secondary (full shift out). There are a number of possible contributing factors.

First check to see that both clutches are in good order (see above), and the motor is not twisting under full load.
 
here is another thing that few consider,,,,,a secondary clutch that is tuned to backshift easily (like many roller clutches) can grenade ANY belt, even with perfect alignment, if the surface you're running on changes from low to high drag. For example, if you're running at high speed on ice or a plowed road, and suddenly the surface changes to significant snow, the helix will crank down and attempt to backshift the primary that is spinning at max hp. result is tension on the belt that will exceed its yield point,,,,BOOM
 
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