STM gas valves

kfs · Jan 9, 2018

Wondering how many guys have bought these and had problems with them opening up after you cruising along at 5000 RPM's and try to whack the throttle and it will not get above 6000 RPM's and your fuel mileage is horrible I am having this exact issue right now but if you start from a dead stop and hit the throttle it will blow right past my problem to max rpm my valves are not opening till 6800 rpm's I know this because I Dynoing my motor I am getting less than 5 miles per gallon at cruising at 5000 RPM just went out tonight with my son on the trail and road 56 miles and a 12 gallon tank was bone dry

kfs · Jan 11, 2018

Nobody's running these supreme tool valves at all

Skywest · Jan 22, 2018

So, did the problem start when you installed the valves? Do you have the bellow style or the piston style? What kinda Sled? Need more info.

Thunder101 · Jan 22, 2018

I had the bellow style back when I had a big bore Firecat and the thinking then was they would open earlier and you would start to make more HP sooner. The newer ECU opens the valves in stages and sooner.
My thoughts on them now is to just think how the Poo 800 did with the mech valves. The ECU has no idea when to add the fuel for the larger E port. As for your bad mileage check your air fuel ratio. If this was a carbed sled then you could blame the valves.

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STM gas valves

kfs

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kfs

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Skywest

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Thunder101

Well-known member

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