Pin weight adjustment

[Tmann]

Took my drive clutch apart and am trying to drop weight to gain top end RPM's. I'm tired of running on setting 6 all the time just to make 7800-8000 @4K. At Baker elevations it's dropping down around 7200 RPM around big house area and above
Looking at the rollers there is a small bolt that threads into the roller pin. This is made of aluminum and does not have much weight at all. I would be surprised if this weighs in at 1gram. (going to put on the scale tonight) Am I looking at the right parts? There are no allen head screws down inside the hallow pin that passes through the roller. Any suggestions? Could the weight be in the hallow shaft itself which would be determined by the thickness?

 

[revx827]

How old are your primary and secondary springs?
You could also go to a slightly higher finish for the primary.

 

[Tmann]

New springs which were the recommended by rooster.

 

[gman086]

Pull those bolts and just run hollow. Readjust clickers to 3 and see how she does.

Have FUN!

G MAN

 

[Tmann]

Looking at this and thats what I decided to do. Have set on click 4 and heading to baker. Due to less weight will this increase clutch heat or will it not have an effect on that?

 

[winter brew]

Need more info....what sled, engine, what clutch setup? Heat will always be the least when running the proper peak RPM....higher or lower means less efficient and more heat.
Is it possibly not a calibration issue but rather a clutch wear or power output issue?

 

[BBP]

The bushing in the spring cap looks destroyed. That will kill RPM's.

 

[Tmann]

Rooster, this is a stock 670 summit 1996. Chain case gearing and cogs geared down when converted from 136 to a 144.
I picked up the yellow primary spring early season from you, not sure exact lb but in the hood of 160/260 I think it is 10 lb up from stock numbers. Off the snow and on packed trails can pull 8000+ RPM's. Elevated track in garage tapping break watching sheaths move. All seem to function but possibly not in perfect harmony. Spark plugs are chocolate brown.

Secondary clutch moves at 17-18 lbs Helix is close to stock 45 or 46 i think.

 

[Tmann]

BBP, the bushing in the spring cap is smooth and does not appear top have excessive play. Can those be replaced without purchasing a new cap?

 

[BBP]

It sure looks like half the surface material is worn off that bushing. Yes, you can replace just the bushing, but it's kind of a pain & the whole cap isn't that much more.

 

[Tmann]

OK, taking a gram off each roller didn't change much. On clicker 4-6 same top end RPM. Now time to look into engine. Does anyone know what the compression of a stock 96 670 ski doo summit should be? I have a buddies 97 670 summit and his compression is 148 psi. I'm guessing mine should be close but haven't check yet. My manual tells me everything like squish and ratio but does not tell me a PSI.

 

[mbret2004]

Psi

Compression between 130-150 is good. Depends on engine mileage, ring wear, ect. Don't be alarmed if it's a little lower.

 

[Tmann]

Both cylinders were at 145 psi.
Rooster, when are you done taking time off. May need to drop this off at your shop.

 

[gman086]

You're running a straight 46 helix on a 670 after going to a 144 track?! You're not opening the secondary enough because the finish angle is too steep so you aren't getting full shiftout under load. Also what belt are you running? The Dayco belts will be 100-200 rpm lower than stock. Try a NEW stock belt. Also make darn sure the TRA arms and rollers move FREELY!

Have FUN!

G MAN

 

[winter brew]

Just let me know if/when you want to bring it down and I will be there.
I agree with gman about checking those things.....IMO the helix is probably fine depending on the rest of the setup. I always ran a 47 or a 44 with no issues so you're in the ballpark.