apv valves question ... rant

[stormtrooper]

What am I missing with the complexity that the manufacturers are incorporating into these things? I rode skidoo for years with the old school rave valves and never had issues with bogs. Then comes the new generation with the cheezy cables and cheap servo actuators ... more things to break, stick, go out of adjustment, etc. From my understanding they are only 3 position, closed, half open, and open. Is it an emissions thing? My m1000 (2500ft) at home when feathering the throttle around 6500rpm sounds and runs like crap. Convince me not to buy the Stm valves. Its not the can, you can just hear it better with the can on.

 

[TROLLCAT]

yeah its a emission thing , and a sound thing there trying to kill two birds with one stone

 

[Turbo-North]

Horsepower and torque too. Short port long port. Short port more torque and low end power Long port high end horsepower. If they are out of adjustment they ussually wont rev or get boggy. Are they clean? What can some guys had issues with certain cans.
Not sure about the STM valves. I eas headed that direction too but 800 miles and still stock setup. No problems. I did break 1 cable early on but have had no issues in over 600 miles. The cable got close to the pipe and the heat caused an issue and the cable broke. I know of guys going 1000, s of miles with no issues . The STM,s had a bad habit of blowing apart i heard. Would imagine that is fixed but!!!! Route the cables away from the exhaust , make sure the are adjusted correctly and clean. Then ENJOY !!!

 

[Turbo-North]

The M 1000,s have a lean spot high rpm low throttle opening. I try not to run mine at speed and hold partial throttle for too long. I have a slight bog at times low alt but it goes away at higher alts. Seems to run rich below 3000 ft. Was thinking it was a break in issue so will watch and see if it does it this year also. I run an SLP can never had issues with it burbling like you describe. We are around the 2200 ft range here too. Gets above 4000 ft pretty quick when we ride though.
OK pretty small http://www.snowestonline.com/forum/showthread.php?t=218769 Scroll down it gives you all the info. 6500 is full open. Could be 1 cable is a little out of adjustment or both are off a bit.

 

[0neoldfart]

Have a set of STM valves in my 07 M1000 that I installed when new. No problems so far, clean em every year, smoother power delivery in my humble opinion. I recommend you use blue loctite on the fasteners, as they will back out otherwise.

 

[stormtrooper]

Have a set of STM valves in my 07 M1000 that I installed when new. No problems so far, clean em every year, smoother power delivery in my humble opinion. I recommend you use blue loctite on the fasteners, as they will back out otherwise.

How do you know how to set them? If I remember right they are adjustable.

 

[stormtrooper]

Ya thanks. I have them adjusted right and they are working according to design. I just don't understand why the complexity is so important compared the old spring ones I had on mach z. My bog seems to go away at elevation as well, but I'm not sure if its because of the fuel program or if it just because I dont normally have the throttle feathered when in the mountains, its normally 0 or 100% . Now I thinking its fuel. Do you have egts, is that how you know you have a lean spot at low throttle?

The M 1000,s have a lean spot high rpm low throttle opening. I try not to run mine at speed and hold partial throttle for too long. I have a slight bog at times low alt but it goes away at higher alts. Seems to run rich below 3000 ft. Was thinking it was a break in issue so will watch and see if it does it this year also. I run an SLP can never had issues with it burbling like you describe. We are around the 2200 ft range here too. Gets above 4000 ft pretty quick when we ride though.
OK pretty small Cat Torque/Tech/Specs here. - SnoWest Snowmobile Forum Scroll down it gives you all the info. 6500 is full open. Could be 1 cable is a little out of adjustment or both are off a bit.

View attachment 116543

 

[Turbo-North]

NO EGT,s just read it somewhere, Can,t remember where .My dealer told me the same don,t run em like that they tend to run lean. Might be the programming in them. Mine seems fine so far this year , no bog. They do adjust at alt seem to be richer at lower alt. Course they are a Mountain sled LOL . Only got 60 miles on mime so fr this year and no bog. Was 3000 ft and -5 so should have been an issue if it was going to be. The fuel pumps in the early 100,s was an issue. SOme did not give the pressure they needed so thats why the updated mapping. Also why guys with Boondockers all seem to use slightly different numbers. Had a Pure Logic box on mine but couldn,t find a happy medium it added fuel start to finish so you had to do a fuel pull to get it set. Really ran rich then low alt ! Not sure wht to tell you. Buy EGT,s or an AIr/Fuel moniter and then you will know for sure!

 

[0neoldfart]

How do you know how to set them? If I remember right they are adjustable.

Spring rates are good from STM, I set mine on a trackstand so they begin to move @ 5000 RPM (about 3 clicks from bottomed out) @ 2300' (my home elevation). The newest units from STM use a signal line (cylinder pressure) - I believe they can be used with boosted sleds without issues. Hope this helps you.