Chasing 8150 rpm

[Teth-Air]

FYI for those guys clutching a 08 or 09.

2500 kms and have been tweaking clutching of my 08 154x xp from new.

mbrp can, 20 top gear, 414 ramps, 12mm + 8mm + 8mm set screws in each primary pin, slp head, 377 belt and blue/purple primary spring.

Observation:

Just can't get as much track speed at 8150 rpm in clicker 3 than I can get at 7700-7900 in clicker 2.

This thing just keeps picking up speed when clicked down but seems to just hang there at 72-75km/hr at the recommended 8150 rpm. In the same pull over and over, I am seeing at least 5 km/hr more when the on the lower clicker?

I will add more weight or try a blue/blue spring, then try clicker 3 again but I am wondering if this head and can combo has lowered the rpm of the peak hp while increasing the mid range torque?

Clutches feel warm with either setup but not too hot to hold with bare hand.

Any thoughts on this as I would hate to leave much desired h.p. on the table?

 

[DaveB]

I would try a blue/blue spring....weight to hold clicker 3...try again. I've always had good success with the blue/blue and have a new one sitting here to try as well.

 

[Teth-Air]

I would try a blue/blue spring....weight to hold clicker 3...try again. I've always had good success with the blue/blue and have a new one sitting here to try as well.

The Baker Boys (Ken and Daryl) swear by them too.

 

[mountainhunter]

spent some time thinking about this after my first ride on my 09 163.and was talking to tuner type who is on this 4m often and he said there is not a big difference in hp from 7800 to about 8300,so should a guy be happy with that higher track speed at a lower rpm. or is the primary not keeping up with the secondary . and if the 09 setups are biased towards a lower elavation,maybe the 600 summit specs would work better 41/45 helix vs 43/47.thinking that at higher elavation a 800 would be more like a 600 at a lower elavation

 

[geniefixer]

I have seen this same thing on 900 cats. Some engines like to loaded more. More load=more heat which usually will keep a two stroke making more torque. HP is nice but torque is what is really making stuff happen. Changes in exhaust can and pipe can also contribute. Just changing a can has the potential to really effect the performance by changing the outlet size. This is really crucial when dealing with the effects on pressure waves in the pipe.
As far as it goes though I will always take track speed as long as it will still back shift.

 

[Throttle Junkie]

The outlet size of the pipe controls all the backpressue the can has nothing to do with backpressure in the pipe.

I have seen this same thing on 900 cats. Some engines like to loaded more. More load=more heat which usually will keep a two stroke making more torque. HP is nice but torque is what is really making stuff happen. Changes in exhaust can and pipe can also contribute. Just changing a can has the potential to really effect the performance by changing the outlet size. This is really crucial when dealing with the effects on pressure waves in the pipe.
As far as it goes though I will always take track speed as long as it will still back shift.

 

[triple7]

The outlet size of the pipe controls all the backpressue the can has nothing to do with backpressure in the pipe.

True...and false. Most of the backpressure in the pipe is produced by the outlet of the pipe, but coupling a loose pipe outlet to a tight can will produce more back pressure in the pipe.

The biggest thing that putting a can, such as mbrp, on the xp does is shorten the stinger length. A shortened stinger length on a two stroke engine bias's the torque peak down in the rpm band...generally

Teth-Air, I believe that is probably why you are seeing your sled want to pull max track speed a couple hundred revs lower than skidoo claims is optimum. JMO

 

[knee deep in it]

this makes sense.

I installed an MBRP can on my 07 800r and now it wants to rev past 8200. Should I drop a clicker position?

 

[Teth-Air]

Thanks guys, your thoughts have helped me decide how to approach this issue. I am going to Golden B.C, this Sunday and taking a blue/blue spring with me and some weights. I will try to dial in 8000 on these pulls and see if this is the sweet spot.