How to Machine the Primary

[SharkAttak]

what are the benefit? top end? bottom end? both? what?

 

[DYNAREX]

its done to increase top speed by overdriveing the clutches more
although if gearing is dropped the acceleration will be better too-and the top end will stay the same

 

[SledFreak]

We've machined........wait I don't want to think back to how many we've machined so far this season. LOL! Rework the primary and unless using an OEM helix then recut inner hub, etc. It's pretty painless, but does require rebalancing. Do a search on here the exact measurements to cut have been mentioned before.

Is re-balancing imperative? If you have removed an equal amount from the entire diameter, why would you need a re-balance and what does that entail.

 

[SledFreak]

Re: washers

the coil bind realy applies to those running the white or pink springs as there just is not the room allow the clutch to fully open with these spings. so even with cut helx,s . this is only one solution to this problem. i have done lots of testing on this. a yamaha sillver is about the softest spring that you can run and is the strongest that yamaha spring that will give room to compress due to coil diameter. dolton offers a sping with more side psi with the smaller coil diameter. so its not just a simple thing like cheating on the boss cut down in order to get max shift out with a o/d primary set up you would need a spacer at lest 4mm thick with a stk primary you would need 1-1.5 mm just for the spring alone. unless one of the other springs is used.

So Black John, what setting on the stock helix would the silver spring be set at? 110? Will that equal 60 degrees on the Yamaha White Spring without the coil bind. That's what I am running is a White Spring @60 degrees, but I'm not sure if it is coil binding or not.

 

[SharkAttak]

do you have to machine both the primary and secondary, how much more gain in top end do you get if you have an attak, isn't the gearing lower on those compared to the apex?

 

[SledFreak]

Attack gearing is 23/38. Apex is 24/38. The best for the buck on an Attack is to buy a Proline Clutch kit. They work great in an Attack, but the Apex needs to much traction to make it work. 121 vrs 136 equals great traction. The Clutching in the Apex is pretty good, except it has ahard time shifting out all the way. I would try that first or call Ulmer, I believe he can point you in the right direction with Machining and clutch kits.

 

[SharkAttak]

Attack gearing is 23/38. Apex is 24/38. The best for the buck on an Attack is to buy a Proline Clutch kit. They work great in an Attack, but the Apex needs to much traction to make it work. 121 vrs 136 equals great traction. The Clutching in the Apex is pretty good, except it has ahard time shifting out all the way. I would try that first or call Ulmer, I believe he can point you in the right direction with Machining and clutch kits.

thanks, already have the ulmer stage 2 kit in my attak

 

[Srxspec]

You must rebalance the clutch because when you machine the primary you have to remove the stationary sheave and machine down the split collars. When you remove the stationary sheave and reinstall it the balancing marks from Yamaha are not in the same position as they were when new. You now have to have it rebalanced due to the different orientation of the stationary sheave.