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Blowing Belts on T-Nytro

Summitseeker

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Dec 3, 2001
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British Columbia
This is my first season on a Yamaha since the early 90's and I do not know much about clutching and am looking for help.

I am going through at least one or two belts every ride and I have to get a fix! I am glad Yamaha belts are cheap compared to Doo!!

I had a local Yamaha dealer do an alignment and shim the spyder gear in the primary but still blowing belts. I only got 15 KM on a brand new belt on Saturday before cord came out the side. Granted there was 4 feet of fresh powder and I was running 16 pounds of boost! :)

The secondary is getting brutally hot which leads me to believe the belt is spinning in the sheaves, hence I figure the problem is with the secondary now. I do have belt squeal at idle. I was also reading a post by Tuesday and I think the belt is actually sitting lower than it should be in the secondary. Any recommendations?
 

Tuesday

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Nov 26, 2007
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We need more info. What turbo, what are you running for boost, what track, what do you have in clutches, what gearing, snow conditions, etc. In 2000km I have never blown a belt just worn them out.

Squealing typically means your deflection is off.

Fill us in and we will see if we can get you on the right track.
 

Summitseeker

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Thanks for the responses!

Running MCX 270 upgrade kit.
Track is a 162 x 16 x 2.5 Camoplast Extreme
Running between 14 and 16 pounds of boost
Arctic Cat purple spring
Using 8DN-17641-01-00 - Yamaha V-Belt
Conditions are usually deep. Saturday 4 plus feet of pow.
Not sure about the helix, rollers or gearing but could pull it apart this evening to find out.

Saturday was the first time a cord came out, I usually just disintegrate them into hundreds of tiny pieces.
 

Thistledoo

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yup we need to know whats up....all the stuff. Any snow getting in there? belt slipping? Laird and I have this issue especially on the heavy left hand doughnuts....some duct tape and it seems alot better for sure.

WOW I have never seen a yammie belt disinigrate...ever.

Some of the clutching is way off and the gearing is to hi I bet....plus you need a cat green spring
 

summitboy

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Nov 26, 2007
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Let's hear about the primary as well spring, weights etc. Are you running stock ? What are you seeing for RPM ? How many km on this sled ? Also belt squeel at idle may just mean worn secondary bolts. You are building major heat to make them blow up. I have had that happen before LOL.
 

Summitseeker

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More info:

Primary Spring is orange/silver/orange (35 KG preload)
8BV51 45 degree helix
Purple EPI Spring set in 3 and 9 positions (120 pounds)
I run at about 8600 RPM at peak.
14.5 mm rollers
(Not sure on the gearing)

The sled was originally setup by Prince George Yamaha.

I think I am going to try the cat green spring and a 47 straight (8BV71) helix or may try a 44/48 progressive helix.

On the green AC spring, what should the positioning be?

Again....any recommendations would be appreciated.
 

summitboy

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What primary weights ? Gearing ? Let's finish the piece of the puzzle ! LOL
 

summitboy

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Nov 26, 2007
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What primary weights ? What RPM are you pulling ? Gearing ? Let's finish the piece of the puzzle ! LOL
 

Summitseeker

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I was geared 20/40 and when I dropped to a 19 it helped alot with belt issues. I just switched to a shockwave helix and so far I like it....being able to change angle for snow is sure nice. pull the cover and lets see what gears you have.

Thanks!! I will pull the cover tonight and have a look. I found this thread http://www.snowestonline.com/forum/showthread.php?t=146050&highlight=shockwave+helix and see you guys posted some good info there too!

Trying to find a 47 degree helix but looks like they are on backorder, I also ordered shims for the bolts on the back of the secondary and will get the green AC spring on order today as well. I think my EPI purple has become weak which could be contributing to the problem.
 
W

Washy

Active member
Feb 14, 2008
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The one thing I ran into last year was I bought an EPI purple spring and it did not work at all. Turns out it was a D&D purple spring not EPI. They are very different. D&D purple no where near as heavily sprung as the EPI one. Just saying because you must be Herculese to get that EPI purple wound to 120 degrees(3 and 9)

Need to know what weights also.
 
N
Jan 11, 2008
142
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18
Cherhill AB
The one thing I ran into last year was I bought an EPI purple spring and it did not work at all. Turns out it was a D&D purple spring not EPI. They are very different. D&D purple no where near as heavily sprung as the EPI one. Just saying because you must be Herculese to get that EPI purple wound to 120 degrees(3 and 9)

Need to know what weights also.

When you are saying wound to 120 degrees (3 and 9) where are you getting the numbers, I see them on the helix but not on the clutch itself. Sorry for a not so smart question
 

Summitseeker

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Dec 3, 2001
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British Columbia
When you are saying wound to 120 degrees (3 and 9) where are you getting the numbers, I see them on the helix but not on the clutch itself. Sorry for a not so smart question

There are some intrusions on the clutch sheave that are marked 1, 2 and 3. You may have to clean it to see them as they are small. Then the helix is marked with numbers as well. Note the 6 and the 9 have a line underneath them to make sure you know what number is actually 6 and 9.
 
H
Nov 28, 2007
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1
8
43
This is my first season on a Yamaha since the early 90's and I do not know much about clutching and am looking for help.

I am going through at least one or two belts every ride and I have to get a fix! I am glad Yamaha belts are cheap compared to Doo!!

I had a local Yamaha dealer do an alignment and shim the spyder gear in the primary but still blowing belts. I only got 15 KM on a brand new belt on Saturday before cord came out the side. Granted there was 4 feet of fresh powder and I was running 16 pounds of boost! :)

The secondary is getting brutally hot which leads me to believe the belt is spinning in the sheaves, hence I figure the problem is with the secondary now. I do have belt squeal at idle. I was also reading a post by Tuesday and I think the belt is actually sitting lower than it should be in the secondary. Any recommendations?
How about moter mounts
 

Summitseeker

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Lifetime Membership
Dec 3, 2001
1,092
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British Columbia
How about moter mounts

I had my dealer do an alignment so it is not the motor mounts but thanks!

It is definitely belt slipage.

I purchased a Shockwave Helix
Purchased Green Actic Cat 0748-025 Spring and mounted in positions 1 and 0
Shimmed the secondary so the belt is 1mm on top of the sheave
Purchased a aluminum plate that bolts on under the clutch to stop snow.
Purchased and Installed new wear bolts on the back side of the secondary.
Siliconed up all possible holes were snow could get in.
Purchased three new Yamaha belts just in case this recipe does not work! :D

I have not ridden the sled yet since these changes were made but will find out on the weekend.
 
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