Ok guys what is the stock primary TRA spring, as in pressure numbers.. I have a 97 MXZ 670 with FAST twin pipes and I would like about 200 more RPMs and was wondering if it could be had by replacing the stock spring. The sled has 1700 miles on it and have no clue if any clutch work has been done so far. Clickers appear to be set at 4 already.

cwarner, the stock spring is a 130-260. What rpm doo you have to spin your engine with the twin pipes?

Do you mean that you want 200 more top end RPM, or engagement?
If you're talking about top end I think you can get that by turning the clickers one more click.

After 7 years, the stock spring might be 'squished' and sometimes in a case like that just buying a new stock spring might get you back to where you want to be...

Ok I am looking for 200 more RPMs up top because I was told that the twin pipes need it for the powerband and want the stock engagement RPM. It turns 7800 full throttle and agree that although it is a low mileage sled it feels less snappy than at the beginning of last year. How many RPMs do you get when you move the clickers one number up?

you get between 100-200 depending, as all sleds are differant, one word of advice though IF your spring is over 2 yrs old CHANGE IT BEFORE YOU TRY TO TUNE YOUR CLUTCHES.

I would contact fast to find out what rpm there twin pipes are supposed to run at, I would thing somewere around 8400-8600 . Lighter pins & a new sping will be needed. They may give you a base line to start at.

The stock spring is 160-230. Fast didnt recommend a change of spring with their setup. With that being said, their setup sucks.

Try this if you like:

Fast Twins
501 valve with gutted box or the Fast 150-80 with K&N's
short boots
145 ramps
200-320 spring
solid pins
50 deg @ 16-18 pounds
24-44 gearing
Head cut to .065 no lower if at low altitude.
.8 mm base gasket.

If you like the twins this setup rocked for me with the correct jetting for the day.
The twins are fussy. I could never get then to work with the airbox. 82-8400 on the tach. You NEED to gear down. If you are still at 26-44 regear.

The single is a better way if you dont like to fuss with it.

Take the primary and secondary apart to see whats in there.

Bought the sled with the twin pipes already thee with 690 miles last september. It is my first time owning a sled. I really appreciate all the advice guys but as we all know have to do one thing at a time. If I stepped up to the 200/320 spring where would that put my engagement RPM at? I will be pulling apart the clutches soon to clean them and check out the settings. So regardless the spring in it is going to be removed because it is old enough to of sagged a bit by now.
I have seen the other mods like the rotary timing and the head shave but are they really nessecary? I got a heck of a deal on the sled and knew the nature of twin pipes but also want reliability. The power is really pretty good just want it to be somewhat efficient through the clutches.

The engagement RPM is based mainly on the Ramp, spring and somewhat the pin weight. We cant recommend a spring until we know the ramp. Fast setup was for 228 ramps instead of the stock 286's. 145's are a 228 with an engagement notch.

Doo tachs usually read high. 7800 on the tach is between 7600 and 7700. You would actually have less power than the stock single running it this way. You need to see "at least" 8200 on the tach for those pipes to work.

You dont need the short boots, base gasket, head cut and RV BUT it makes a world of difference with those twins. Doo used these tricks on their twin piped mach 1 670's.

Are you running the stock air box? Is it Gutted?

Ok clutch is stock. Clickers set at 4. Other than that I myself have not messed with it. So being clutch ignorant that I am what will the 200/360 spring do for me?
Thanks for all the patience guys I appreciate it!