I can't rev over 7 G's. How do I check if exhaust valves are opening?
How Do You CHeck If Exhaust Valves are Working?
- Thread starter whetsel.m
- Start date
put it up on a stand and have someone rev the engine while you look at the top of the valves to see if they pop up
C
chunkysoup
Well-known member
Remove the valve from the engine and reassemble as a whole unit. compress the guilotine into the body of the valve then hold ur thumb over the hole on the cover. release the guilotine and if it doesnt retract to fully extended then ur bellows are fine. if the guillotine retracts to fully extended the bellows either have a tear or hole in them and need to be replaced.
could be a clutching issue as well?
To avoid dismantling the valves, couldn't I take one of the hoses from the valve and apply pressure. Then check to see if the pressure holds for a period of time?
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CompFusion
Well-known member
You can apply low air pressure to the hose. Excess air should escape into the cylinder....if it doesn't then the orifice into the cylinder is plugged. During this time you should see the tip of the valve nut through the hole in the cap while under pressure.
so will all the pressure leak into the cylinder?
Exhaust valves require routine maintenance so I would recommend dissassembly for inspection and cleaning.
Remove covers and look for oil on top side of bellows. Any oil indicates leakage and need to be replaced. Don't lose springs!
Remove nut in centre of bellows then remove bellows and note which side up on washer below it. Washer only fits 1 way.
Inspect bellows for cracking etc.
At this point check valve for up and down movement. If they move freely you could get away with just checking for any blockage of passage to cylinder. Brake clean and compressed air does a good job. It is a small passage, make sure it is clear. I prefer to completely dissassemble, so valves can be cleaned and inspected. If you have gaskets continue on.
Remove vent lines. Remove 4 allen bolts, lift assembly and valve out of cylinder. Clean, inspect then reassemble with new gaskets.
Another area to check is the vent lines and solenoid. The default position for solenoid is closed. You would assume that if it stuck, exhaust valves would still open. I found mine so dirty that when it was closed air was still leaking past and valves wouldn't open. Took a while to figure that one out. I lose 3 to 4 hundred rpm when they don't work. Sled has 1100 miles and have replaced 2 cracked bellows plus the solenoid issue. Kinda strange because my 800 had almost 3000 miles and never replaced a bellows, just cleaned valves every year.
Remove covers and look for oil on top side of bellows. Any oil indicates leakage and need to be replaced. Don't lose springs!
Remove nut in centre of bellows then remove bellows and note which side up on washer below it. Washer only fits 1 way.
Inspect bellows for cracking etc.
At this point check valve for up and down movement. If they move freely you could get away with just checking for any blockage of passage to cylinder. Brake clean and compressed air does a good job. It is a small passage, make sure it is clear. I prefer to completely dissassemble, so valves can be cleaned and inspected. If you have gaskets continue on.
Remove vent lines. Remove 4 allen bolts, lift assembly and valve out of cylinder. Clean, inspect then reassemble with new gaskets.
Another area to check is the vent lines and solenoid. The default position for solenoid is closed. You would assume that if it stuck, exhaust valves would still open. I found mine so dirty that when it was closed air was still leaking past and valves wouldn't open. Took a while to figure that one out. I lose 3 to 4 hundred rpm when they don't work. Sled has 1100 miles and have replaced 2 cracked bellows plus the solenoid issue. Kinda strange because my 800 had almost 3000 miles and never replaced a bellows, just cleaned valves every year.
O
otterpoo
Member
Sounds like a torn bellow issue, or at least a exhaust valve problem. I was having high RPM and top speed issues. After doing an exhaust valve rebuild and cleaning the issue was taken care of, and it ran crisper with better throttle response and faster RPM gains. You could just remove the car of the valves for a quick inspection making sure to hold the cover down while removing bolts so you don't lose the springs.
Just a thought.
Just a thought.
I plugged the lines coming out of the valves with a bolt an got my R's back, so either the solenoid isn't closing or one of the hoses are leaking. How many volts does the solenoid take to make it work?
C
CompFusion
Well-known member
If the sled works ok with the hose plugged that pretty much eliminates the valve system and points to a gunky solenoid as the culprit. When mine failed I tried a combination of brake cleaner and air pressure to blow it out but in the end had to replace the piece.
