Trying The 8DN BELT

[sxr70001]

This is exactly what's been bothering me about this change. Except you say it so much more clearly.

Could the fact that the 8DN is a deeper belt be making up for some of the extra length and that is why the performance is still close.

 

[suburban]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper

you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works

 

[stingray719]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper

you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works

I suppose you have never used different length belts for clutch and gearing tuning? Alot of us have.

Tell you what, find and post the length and more importantly the acceptable belt length limits as per too long or too short as belts vary from manufactoriing. Post results from 8Jp, 8DN-00 and 8DN-01 and then lets talk. I am not posting them as I already know the tolerances.

Or, call Ulmer and Hartman and tell them they are wrong and you are right either will do.

 

[BETHEVIPER]

[/quote]


you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works[/quote]

shimming the belt will work after engagement but you are now starting with different gear ratio and belt loads compared to the shorter belt.

as for the 8jp belt working, I have no idea, other than people telling me what a piece of crap it is and that their viper is the slowest yamaha they have bought.

 

[stingray719]

you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works[/quote]

shimming the belt will work after engagement but you are now starting with different gear ratio and belt loads compared to the shorter belt.

as for the 8jp belt working, I have no idea, other than people telling me what a piece of crap it is and that their viper is the slowest yamaha they have bought.[/quote]

Yes the belt is longer but look how little more the length is. And yes you can smoke the 8jp very easy. Puzzles me why Yamaha put this belt on, I suspect this is not the belt that was supposed to be on it and a cost cutting measure after engineering is responsible. As you seem knowledgeable with clutching check the actual belt lengths and length tolerances you will be surprised.

 

[DeerHuntr]

I am thinking about re-shiming my secondary and trying a 8dn again with my secondary wrapped to 6/2 just to see if I still bump the limiter like I did with the 8jp. At 6/1 wrap it all but cured my Rev limiter issue but I still hit it occasionally but it feels like I lost some midrange vs my 6/2 setting. Both are much better than my stock settings my machine came with. The argument that the little longer length of the 8dn is gearing the machine down is correct I think but I don't see the problem with that. There is no way a stock Viper is going to pull itself out of gear anyway, aren't they geared for 115 or so?

 

[YamahaTim]

I am thinking about re-shiming my secondary and trying a 8dn again with my secondary wrapped to 6/2 just to see if I still bump the limiter like I did with the 8jp. At 6/1 wrap it all but cured my Rev limiter issue but I still hit it occasionally but it feels like I lost some midrange vs my 6/2 setting. Both are much better than my stock settings my machine came with. The argument that the little longer length of the 8dn is gearing the machine down is correct I think but I don't see the problem with that. There is no way a stock Viper is going to pull itself out of gear anyway, aren't they geared for 115 or so?

Mine was exploding the 8JP. 4 times. Different clutching and it still did. Went to stock yamaha parts and still exploded. Shimmed changed belt to 8 DN and same clutching and no issues. I'm ok with losing a little top speed to have a belt last for more than 300 miles!! And a 100 dollars a piece. I need a better clutch kit now to take max advantage of my belt. I am waiting for Allen at Ulmer to get me going. He is testing. I see on the trail 106mph and to me that's just fine! I'm not a big lake racer. I will do it for the fun of it, but I won't set my sled up for it. No reason. I want to get from one corner to the next fast and without exploding a belt!!

 

[DeerHuntr]

I don't think the longer belt will hurt top end in reality, we aren't getting full shift out with the 8jp anyways.

 

[09nytro]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper

When I checked my center to center it's at 263mm ( posted about 10 pages back )
And you are not ranty at all , I must say you hit the nail on top of the head but I will also say you will not get it though some of these guys heads ......

 

[09nytro]

I don't think the longer belt will hurt top end in reality, we aren't getting full shift out with the 8jp anyways.

How do you know if you are or not ?

I'm seeing 104mph on my junk #*$&@ 8jp belt with 2300 miles on it !

 

[09nytro]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper

you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works

I suppose you have never used different length belts for clutch and gearing tuning? Alot of us have.

Tell you what, find and post the length and more importantly the acceptable belt length limits as per too long or too short as belts vary from manufactoriing. Post results from 8Jp, 8DN-00 and 8DN-01 and then lets talk. I am not posting them as I already know the tolerances.

Or, call Ulmer and Hartman and tell them they are wrong and you are right either will do.

I must say I haven't , I tried it for the first time with this sled and it didn't work !

And I called Allen and Tom but they haven't got back to me yet , oh and I did talk to loan at thunder products and he just laughed !

 

[YamahaTim]

Laughed at what??

 

[09nytro]

Putting a longer belt on !

Your primary may be shifting out all the way but secondary isn't !

 

[suburban]

Putting a longer belt on !

Your primary may be shifting out all the way but secondary isn't !

Thats the new speed secret !!

 

[YamahaTim]

Putting a longer belt on !

Your primary may be shifting out all the way but secondary isn't !

Well like I said I would rather lose a little top speed, and have a long lasting belt vs. 2 mph and only 300 miles. It's weird why it works for some and not others. I don't understand it. Or do I really believe that I'm really losing any top speed. I know very few people are saying that it's capable of speeds of 117. I won't do that with my 1.6 lug track anyway. Or do I have a road that is iced over that I could do that on anyway. I'm more worried about how fast I get there. And mine will do 104mph in a 1000 feet. And I'm happy with that! That's what I want out of it! I don't care about racing across a lake. Corner to corner! That's what it's about!