APV vs STM

tchriste · Jan 12, 2016

I run a 925 BB and have been having an RPM issue. I aim for 8300 RPM however more often than not I don't get higher than 7700. I have no codes and the APV cycle properly every start-up. I have reset the cables to 1.377 more times than I care to mention. Have tried the Speedwerx light weight ones as well. Been through all wiring, carried out all tests to no avail so I'm now considering STM valves. Anyone try these and what are the pros and cons. Thanks guys.

Thunder101 · Jan 13, 2016

Sounds weird. I used the stm ones years ago ( bellow style like skidoo ) the new ones are different so I'm sure they are also better. Any chance it's something other then the apv. If you have no code ??

Hardass · Jan 13, 2016

i doubt the power valve is your issue that said i had a set of the stm piston type and they broke wjere the blade screws into the piston there is very little material right at that point.what have you done with your clutching? what do you have in it right now and what elevation

tchriste · Jan 13, 2016

I have been through 3 primary and 2 secondary clutches with different configurations. Replaced wiring harness. the engine itself is very sound and when everything is on the engine pulls a good 8250-8300 at 7500 ft. when it falls off it will instantly pull 8300 then drop to 7700 when the power is needed. I've been through stators and all the electrical to no avail.

Thunder101 · Jan 13, 2016

Your 100% sure no wrench on your display ? Try mounting your knock sensor on the thin steering hoop support.
curious what your A/F is and how much added timing ?

tchriste · Jan 13, 2016

No wrench.....AFR at WOT is 11.6....1.5* added timing...New motor mounts as well.

Thunder101 · Jan 13, 2016

So that's 11.6 at wot at 8300 so what is it when your at 7700 wot

orange 1 · Jan 13, 2016

Did you check for a failed exhaust can? I have seen this several times now, runs perfect until enough pressure builds up in the pipe then the silencer packing would blow over and block off part of the outlet. I know it should show on your afr's but easy to check:face-icon-small-hap

tchriste · Jan 14, 2016

Thunder101 said:
So that's 11.6 at wot at 8300 so what is it when your at 7700 wot

about 12.5 with 1100* on EGT.

New Y-pipe, pipe and can. had the problem with my old set-up and still with my new set-up. My old set-up was a Speedwerx and operated at 8,000 RPM so it wasn't as noticeable as with the new Jawz set-up which requires 8300 RPM to operate.

Thunder101 · Jan 14, 2016

1100* seem cold w a 12.5 a/f , probably not the problem any ways. I would call Greg

vinpie1 · Jan 14, 2016

My 2005 M7 with a 15:1 RKT billet head runs 200 rpm (under hard load) more with a retarded (backwards) 1.5 degree key. I guess it puts more heat in the pipe. The sled pulls hard at 7900rpm all day in any snow condition. Very little fluctuation. Without the negative timing it pulls 7800 at first and settles at 7600-7700 in the pull. Made a huge difference. Easy thing to change out quick and test...

tchriste · Jan 14, 2016

vinpie1 said:
My 2005 M7 with a 15:1 RKT billet head runs 200 rpm (under hard load) more with a retarded (backwards) 1.5 degree key. I guess it puts more heat in the pipe. The sled pulls hard at 7900rpm all day in any snow condition. Very little fluctuation. Without the negative timing it pulls 7800 at first and settles at 7600-7700 in the pull. Made a huge difference. Easy thing to change out quick and test...

interesting....everyone wants to add timing to these things, it was even suggested by Jawz to add 4-6* of timing to the engine while Speedwerx didn't want any added. definitely worth looking at.

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APV vs STM

tchriste

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Thunder101

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Hardass

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tchriste

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Thunder101

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tchriste

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orange 1

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tchriste

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vinpie1

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