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loose blown powervalve base gaskets, could this be part of the bog problem???

my sled has caught the bog and have been working with my dealer to get it fixed. have new injectors that should be arriving today. was begining the tear down yesterday and noticed both my powervalves had oil around the top. after looking closely the right side has blown half of the top of the gasket out. hit them both with a wrench and they were finger tight. my sled would only rev to 7,200 and then down to 6,500 and then back up. i'm a cat convert and had broken a powervalve cable on my mt. cat and it did basically the same thing, would only rev so high and then yo-yo. i see the powervalves on theses are vaccum activated and not a wire, does anyone know if the base gasket on these seal for vaccum??? does anyone know when the powervalves open and close??? found it odd that mine would bog at almost the exact same rpms everytime and then come back to life at the same almost everytime. makes sense to me that if the base gasket does hold vaccum that if they are leaking your sled will only pull up to where the valves are supposed to open, at this point the vaccum leak prevents the valve from opening and that causes it to bog back down to the spot they are supposed to close again...
 
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Yes this would be a definate issue. They work on exhaust pressure not vacuum but same idea. Pressure must build up behind the bellows to overcome the spring and then the valves open. If you have a gasket leak, no pressure build up = no valve opening. Voila!
 
What bolts should I check? Never had a powervalve motor before.

There are 4 bolts right about the black diamond on the front of your motor, those are the Variable Exhaust Valves (VES). 2 of the bolts are short and 2 are long and bolt onto your block. they should be pretty snug, but don't reef them because you'll strip them out. I don't know the toque spec...

Sandman, yea that would make sense why it bogs and bounces around 6500-7200... i believe that is where the valves open around these RPMs. There is a selinoid that fires allowing your valves to almost instantly build pressure and open. this happens at a specific RPM but I don't know what it exactly is... maybe your dealer could tell you or look it up?
 
I"ve seen a few people post up parts diagrams, could somebody post up what this area looks like? Sorry to be a pain, just want to be sure I check the right thing. Thanks!!
 
11800RMKVES.gif

the bolts are numbers 9 & 10. Sandman is talking about a blown bellows which is number 5


EDIT: haha I guess everyone replied to this at the same time...
 
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THE EXHAUST VALVE BELLOW OR PART 5 HAS BEEN A HUGE PROBLEM FOR ME AND MY DAD, WE HAVE HAD A COUPLE SPLIT AND IT CAUSES SEVERE BOG PROBLEMS
 
Wow! So many pics to choose from, let's see... That is great, thanks guys. M8SANDMAN said the gasket was bad, not the bellow right?
 
They are both prone to have issues. The gaskets WILL blow out if the bolts get loose. The bellows are a maintenance item that need to be checked and replaced as necessary. Get in the habit of checking the bolts on a regular basis and clean the valve slides and check the bellows once a year at minimum. (of course that depends on how many miles you ride, type of oil, etc.) Once you start doing it you will get a feel for how often. It is a super easy process.
 
M8SANDMAN said the gasket was bad, not the bellow right?

yep i think so. my bad, the gasket is #2... but like what GKR mentioned, the bellows can get tears in them and blow oil all over the place. get those on your routine maintenance list
 
My service manual is on order.

Anyone have the torque specs for the powervalve bolts?
 
Just checked mine, they were good and snug. Where and what does the TPS look like? I want to check out the connection. Also, checked the plug gap and both were good at .027
Thought I read somewhere that somebody put them to .018 my addendum says .027.
 
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