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Soft Start Clutching Primary Spring Review

Thanks for the suggestions. Belt "deflection" (which the manual calls belt position so wasn't sure)was checked end of last season and it was just barely above (maybe a 1 mm) the secondary housing. There's only about 400 miles on the sled it as a reference. I'll get out this weekend and verify the deflection. I'm going to try the new "soft start" spring and see if that smooths out takeoffs. The good news on the clutch (all stock at this point) is that I was easily able to hit 93mph on the meter on a chain of lakes run, and it still felt like it was accelerating strong. I let off since it was under 200 miles and didn't want to stay on it that long with break-in still underway. I'll see what the top end is and see how the soft start spring works. If the clutch still needs work for smoother starts and top end I'll check into the COTC clutch kit.

Thanks again for the suggestions.
 

rebmo said:
Thanks for the suggestions. Belt "deflection" (which the manual calls belt position so wasn't sure)was checked end of last season and it was just barely above (maybe a 1 mm) the secondary housing. There's only about 400 miles on the sled it as a reference. I'll get out this weekend and verify the deflection. I'm going to try the new "soft start" spring and see if that smooths out takeoffs. The good news on the clutch (all stock at this point) is that I was easily able to hit 93mph on the meter on a chain of lakes run, and it still felt like it was accelerating strong. I let off since it was under 200 miles and didn't want to stay on it that long with break-in still underway. I'll see what the top end is and see how the soft start spring works. If the clutch still needs work for smoother starts and top end I'll check into the COTC clutch kit.

Thanks again for the suggestions.
Click to expand...

Can't stress enough how important the belt deflection is for a smooth take off and low end performance in general. Measuring the belt height above the secondary sheave is really not the best way to set it up. Best way to set deflection would be to raise the rear end of the sled off the ground so the track is freely hanging and adjust the deflection just tight enough so the track is trying to turn or just creep when the sled is a idle speed. An aftermarket belt deflection adjuster makes this very simple to accomplish. With only 400 mi on the sled I wouldn't be doing much else.
 
titanrcr said:
Can't stress enough how important the belt deflection is for a smooth take off and low end performance in general. Measuring the belt height above the secondary sheave is really not the best way to set it up. Best way to set deflection would be to raise the rear end of the sled off the ground so the track is freely hanging and adjust the deflection just tight enough so the track is trying to turn or just creep when the sled is a idle speed. An aftermarket belt deflection adjuster makes this very simple to accomplish. With only 400 mi on the sled I wouldn't be doing much else.
Click to expand...

And everybody has an opinion and that is great. My decades of Yamaha snowmobile repairing and riding has taught me deflection is not near as important as it is to you. The Yamahas have a weird 3 bolt arrangement to adjust belt deflection and as such the bolts wear quick and the deflection changes. Belts wear and deflection changes. You may notice but I have never been able to tell slight changes in deflection while riding.

Is deflection important? Sure it is but it is not a precise adjustment just like track adjustment is not. The take off that rebmo is talking about is caused by the clutch combination the Viper comes stock with, now everybody has there definition of rough take off but in my mind the Viper is ROUGH in stock form. But then I have more than a few sleds here to compare against.

Short version is, rebmo is looking to solve a problem and you are sending him to something that is not going to solve the stock clutched Viper rough take off. Not trying to start a fight but need to clarify issues for our new members.
 
stingray719 said:
And everybody has an opinion and that is great. My decades of Yamaha snowmobile repairing and riding has taught me deflection is not near as important as it is to you. The Yamahas have a weird 3 bolt arrangement to adjust belt deflection and as such the bolts wear quick and the deflection changes. Belts wear and deflection changes. You may notice but I have never been able to tell slight changes in deflection while riding.

Is deflection important? Sure it is but it is not a precise adjustment just like track adjustment is not. The take off that rebmo is talking about is caused by the clutch combination the Viper comes stock with, now everybody has there definition of rough take off but in my mind the Viper is ROUGH in stock form. But then I have more than a few sleds here to compare against.

Short version is, rebmo is looking to solve a problem and you are sending him to something that is not going to solve the stock clutched Viper rough take off. Not trying to start a fight but need to clarify issues for our new members.
Click to expand...

I too am trying to help new members. I did not offer an an opinion. My comment to rebmo, not you, was very basic and true. Decades of sledding and you don't know what effect a loose belt deflection will have? You have proven time and time again that you know very little to nothing about clutching. 2800+ posts on this forum and nothing of value to say. I don't know who your trying to impress but it sure as hell isn't me. BTW I'm not trying to start a fight either.
 
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Stingray, are you going to stick with the soft start spring when you do your EVO turbo?
 
stingray719 said:
rebmo please post back on the soft start spring once you have it in.
Click to expand...
Will do, it arrived yesterday. I should be able to make some determination on how effective the new soft start spring is on resolving my jerky starts by just moving the sled back and forth on the trailer. I hope to get the spring in this weekend. If it smooths out the take offs I might just be so happy I'll run around and start tearing some grass up. On the other hand it's dropping into the 30s already this week and might be able to come to my senses and wait for some snow.
 
rebmo said:
Will do, it arrived yesterday. I should be able to make some determination on how effective the new soft start spring is on resolving my jerky starts by just moving the sled back and forth on the trailer. I hope to get the spring in this weekend. If it smooths out the take offs I might just be so happy I'll run around and start tearing some grass up. On the other hand it's dropping into the 30s already this week and might be able to come to my senses and wait for some snow.
Click to expand...

Yep trailer test will tell.
 
rebmo said:
Will do, it arrived yesterday. I should be able to make some determination on how effective the new soft start spring is on resolving my jerky starts by just moving the sled back and forth on the trailer. I hope to get the spring in this weekend. If it smooths out the take offs I might just be so happy I'll run around and start tearing some grass up. On the other hand it's dropping into the 30s already this week and might be able to come to my senses and wait for some snow.
Click to expand...
Yes it will I have the schmidt bros on my nytro and it moves instantly
 
I got a second wind tonight and wrapped up a few things on the viper including installing the soft start spring. It took all the jerk out of starting from a stop. The stock Yamaha spring was borderline dangerous on my sled especially when trailer loading since it would lurch ahead engaging in the 3500rpm range and you have to really jump on the brake or hold and try to control. It was manageable but not at all what I would expect especially from a new sled.

With the BOP soft start spring installed the clutch engages at about 2600 rpm and is smooth and easy. This is in comparison to moving around on the trailer last season which was the worse scenario for the jumpy starts. This will make sledding on the Viper much more enjoyable. I can recall last year trying to come out of a steep ditch to cross a busy highway and it would either launch which shot me out into the road or spun the track and I lost traction and had to abandon the crossing with cars coming. I never had the jerky start, always smooth on my SXR which my son now rides. I can instantly tell the difference in controlled smooth low rpm engagement with the soft start spring. There may be some reason Yamaha thought folks want a high rpm jerky start up engagement but I'm lost on that one.

THANKS for the awesome recommendation. Thanks BOP Soft Start Spring Highly recommended.
 
rebmo said:
I got a second wind tonight and wrapped up a few things on the viper including installing the soft start spring. It took all the jerk out of starting from a stop. The stock Yamaha spring was borderline dangerous on my sled especially when trailer loading since it would lurch ahead engaging in the 3500rpm range and you have to really jump on the brake or hold and try to control. It was manageable but not at all what I would expect especially from a new sled..
Click to expand...

What is really fun is standing up looking backwards in reverse with it and it engages throwing you out over the windshield pinning the throttle with your thigh.......

Ask me how I know, And I was running 12#'s of boost at the time (with quick spool waste gate) :o| Thank god I had the tether attached and no one was around to laugh!!
 
Yamadog said:
What is really fun is standing up looking backwards in reverse with it and it engages throwing you out over the windshield pinning the throttle with your thigh.......

Ask me how I know, And I was running 12#'s of boost at the time (with quick spool waste gate) :o| Thank god I had the tether attached and no one was around to laugh!!
Click to expand...

Well, I almost had my beer go out my nose :beer:that I was enjoying after wrapping up a few things on my sled tonight reading your post. Thanks for the chuckle. Not that it was funny you almost got hurt but the mental picture could easily be me but then the turbo boost enhancement really did the trick in my mental picture:). I'm hoping you've changed the primary clutch spring to something that can keep you alive with that kind of power. ouch........
 
Crap no I just don't use reverse anymore:jump:

P.S. sorry about causing the beer loss can you recover it or is it lost to the carpet?
 
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