ViperMan700
New member
Hi,
I don't know anything about snowmobiles, especially clutching.
I am having issues getting the RPM up into the desired 8000s.
Here is a link to a video with the issue:
https://www.youtube.com/watch?v=qzr3o58B5U4&feature=youtu.be
When under load driving, the rpm is slightly lower around 6900-7000
These were the 2 springs I had. The Green-white-Green came in the engine when I bought it.
Is the low rpm a clutching or engine issue? I just changed the spark plugs and the compression seems good, although it might be in the lower range. I can get about 115-120psi when cold.
Could I try taking off some grams in the primary weights?
The secondary is from a Polaris 800.
I am pretty lost and am just looking at suggestions where to start, or if there are obvious things that need changing.
Thank you
I don't know anything about snowmobiles, especially clutching.
I am having issues getting the RPM up into the desired 8000s.
Here is a link to a video with the issue:
https://www.youtube.com/watch?v=qzr3o58B5U4&feature=youtu.be
When under load driving, the rpm is slightly lower around 6900-7000
These were the 2 springs I had. The Green-white-Green came in the engine when I bought it.
Is the low rpm a clutching or engine issue? I just changed the spark plugs and the compression seems good, although it might be in the lower range. I can get about 115-120psi when cold.
Could I try taking off some grams in the primary weights?
The secondary is from a Polaris 800.
I am pretty lost and am just looking at suggestions where to start, or if there are obvious things that need changing.
Thank you
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I would start with the stock secondary, can be had cheap on eBay, then get the stock springs and weights, should work perfect.
ViperMan700
New member
I actually have the viper secondary, but without a lathe, it is hard to use because it has a unique size and has splines on the shaft.
The Polaris uses a 1in keyed shaft so it is easy to find barings and sprockets.
The Polaris uses a 1in keyed shaft so it is easy to find barings and sprockets.
Oh, I see, its a go cart, didnt see the video the first time.
IF its a clutching problem, which Im not sure it is, you may need a stiffer secondary spring or setting, to slow the shift down.
You have the correct jetting for the temp I assume ?
IF its a clutching problem, which Im not sure it is, you may need a stiffer secondary spring or setting, to slow the shift down.
You have the correct jetting for the temp I assume ?
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ViperMan700
New member
Thank you for the suggestion.
I will give that a try.
The jetting seems ok, but I haven't driven it that much to tell.
I am venting the carbs to atmosphere and am running the mains 5 sizes below what the chart says in the attachment.
I am at sea level and a little above 60F. Currently running 147.5 main jets.
If the belt is too tight, could it cause this issue?
It's a pain in the *** to put on and will open up the secondary slightly.
I will give that a try.
The jetting seems ok, but I haven't driven it that much to tell.
I am venting the carbs to atmosphere and am running the mains 5 sizes below what the chart says in the attachment.
I am at sea level and a little above 60F. Currently running 147.5 main jets.
If the belt is too tight, could it cause this issue?
It's a pain in the *** to put on and will open up the secondary slightly.
Attachments
you done anything with the needles or pilots?
ViperMan700
New member
I think they were 45 pilots and 2.5 needles buy am not certain. I have only changed the main jets.
ViperMan700
New member
I am going to order another secondary but was wondering how it would limit the rpm with no load.
I understand if you are riding and the shifting isn't working properly you could see limited rpm, but with the back wheels up,
wouldn't it reach max rpm if everything is all right in the engine, just take a little longer to get there. Where would the extra power be going, nothing is getting extremely hot and I am only spinning the wheels.
As I said, I know nothing about clutching and am just trying to figure out the reasoning.
I understand if you are riding and the shifting isn't working properly you could see limited rpm, but with the back wheels up,
wouldn't it reach max rpm if everything is all right in the engine, just take a little longer to get there. Where would the extra power be going, nothing is getting extremely hot and I am only spinning the wheels.
As I said, I know nothing about clutching and am just trying to figure out the reasoning.
Not sure if I understood correctly, but if your offset is too far apart (belt too tight) you won't be able to reach full shift out (nor full backshift).
ViperMan700
New member
Thank you for the suggestion. I still need to test it under load but I removed the collars on the jackshaft so that the secondary could move side to side and sort of self align.
I was able to hit mid 8000s rpm no problem. I was originally bassing the side-to-side offset on what they had in the manual and adjusting for the thickness difference of the Polaris secondary, but that proved to be no good.
It didn't seem to move much but made a big difference, hopefully, it stays that same way under load.
I was able to hit mid 8000s rpm no problem. I was originally bassing the side-to-side offset on what they had in the manual and adjusting for the thickness difference of the Polaris secondary, but that proved to be no good.
It didn't seem to move much but made a big difference, hopefully, it stays that same way under load.
BornYamaha
Member
Do you know if the power valves are opening at the exhaust? That would take a lot of power from the top end. I can't see it but I assume you managed to get the stock Viper pipe incorporated on that thing somehow. You get that thing running right and it's going to be wicked.
It is not running right at high rpm. I would second born yamaha and suggest checking the exhaust valves. I see you have error codes. Even though it isn't in a sled, you should be able to hook everything up and have no codes.
How many miles were on the sled it came out of?
How many miles were on the sled it came out of?