Head shim opinions

seano700 · May 3, 2014

Have a viper with mcx270 on order for fall. Not sure if I should just install the shim, or go with low comp pistons. For those that run mcx what's your advise. I would be pretty happy with 220, no shim and snappy. I rode the 180's and not quite enough for a medium husky rider

. Tks

Sean

jskattum606 · May 8, 2014

Not very lively in the yami forum:face-icon-small-ton
I dont own either but have ridden with shim and without and the difference is very minimal. The 3 cyl motor makes lots of low end torque to over come any downside to lowering compression a little. With that said, I wouldnt want to open the motor all the way up just to put in another set of brand new pistons

BigFish BC · May 8, 2014

seano700 said:
Have a viper with mcx270 on order for fall. Not sure if I should just install the shim, or go with low comp pistons. For those that run mcx what's your advise. I would be pretty happy with 220, no shim and snappy. I rode the 180's and not quite enough for a medium husky rider . Tks

Sean

you could make 220 with no shim but the prob you will have is the fueling wont be the same,so there is a good chance you would need a diff fuel map.the other issue you will have depending on elevation you will need to run about 10lbs boost to make 220hp & you will need to run at least 50/50 112/91 oct & that will be borderline without water to air intercooler.no shim does make a big diff to me but the next guy may not notice it i guess,way better throttle responce.

Climbmax · May 9, 2014

I run a 270 MCX with Head shim. Its plenty snappy and I wouldn't change from their program.
Enjoy
RS

M5- · May 9, 2014

The shim makes a difference for sure but nearly the difference the turbo system plumbing makes. There is no doubt the mid mount Impulse sleds are snappier than the rear mount MCX ones, I've owned both, that said the MCX shimmed motors are pretty much bomb proof. I'm willing to trade off a little throttle response for the gas and go ease of everything else that the MCX kit provides. Slap in the shim, add fuel and ride it at 270, you will never be turning down the boost. There is no point in doing rods and pistons if you are only thinking 270 or less hp IMO and the 270 program is tried and true.

M5

seano700 · May 10, 2014

Thanks fellas

Appreciate your feedback!
Reliability and tinker free are the priorities with this one, so we will keep it simple with the shim.. I was considering pistons only because I want to do this once to get many years out of the machine.

Brad at mcx Canada sent me a brochure on there data logger.. From what I understand it logs, acts as a gauge, and allows the rider to tune the auxiliary fuel map.. Is this a worth while investment? I was thinking of skipping out on the A/f and boost gauges running this in it's place..

I currently have Neil's Boost-it on my Nytro, it woke that sled right up, tuning has never been so easy... Prior to this it was laptops, and cables.. Yuk..

Thanks again!

Sean

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Head shim opinions

seano700

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jskattum606

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BigFish BC

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Climbmax

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M5-

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seano700

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