I was wondering if you can adjust your exhaust vavle on a 500 to get different types of performance in different parts of the power band. If so has anybody done this and how do you go about doing it. Thanks jeremy

 

Im not sure so dont hold me too this but I think I read in here before that you should only adjust it if you have done modifications like pipes jets carbs and so on but adjusting it will make it open at a different rpm level my $.02.

 

The exhaust vavle is very simple. All it does is open up a cavity in the case to the exhaust at a given RPM for more top end. Just like changing expansion chamber while driving. So there is no performance gain by changing the preload of the spring. The spring is wound up If I remember right 3 times, and it needs to be there to return for low end power. It is however general maintenance to clean the exhuast valve because alot of them gum up and stop working rather quickly, and then there is either power loss in top or bottom of the powerpand depending where its stuck. You do have to remove the jug to clean it. Thats why there is an inspection window to look. Look at it at idle, then rev in neutral to 4K rpm and watch it open. If not, its stuck, remove the jug, but first do a compression test with throttle wide open and look for adleast 110...if not adleast buy rings, possible a piston and bore. I like to rebuild mine every season, because with a fresh cylinder its crazy fast. This is the first year I'm not rebuilding it because it blew 160psi, thats really good and its an animal. If you want more power, something is probably wrong...becasue I never have.

 

I have an 87 Zilla,all I do with it is drag race...I had my engine done up by Vito's Perf.,and he told me to disconnect the power valve and close it ,he said it close's at top speed or at higher rpm's...I did it and it did'nt bother my performance....my quad run's in the 4.9's on gas in 300 ft.,it's now got N.O.S. and I need to get it timed again cuz it's really f-ing fast now,the first time I took it to Ubly Dragway it run in the low 13.00's in the quarter.....But any way I'm going to do some research on the power valve to see if there's a hidden secret that Vito did'nt want me to know about cuz I spanked some of Vito bike's he brought to Port Huron.....Zilla

 

i have heard of people closing it completely off due to the fact they just couldn't keep it working. They were having to pull the jug all the time to clean because it was gumming up all the time. I switched to Maxima Castrol 927 at 40:1 and have not had any trouble at all with it gumming up. Before I was running Bel Ray and it would gum up all the time when it would set for a long time. Well I was just wondering if you could adjust it to get different types of performance but I guess the tension on the spring will not affect the performance any. Thanks alot.