Higgsy

Member
Mar 23, 2005
72
0
I cleaned the exhaust valve and installed them back into the cylinder. I noticed that the left side doesn't seem to open at the same time as the right side. Is that operating correctly? When opening the valves past half way the right side opens first then the left opens after. This is the first time I've had the valves apart so I don't know if this is normal.
 
Last edited:

Higgsy

Member
Mar 23, 2005
72
0
When I cleaned them they looked fine. There was only a little bit of carbon build up on the valves. I oiled everything before I installed them.
 
Last edited:

Rotorranch

Member
Feb 10, 2007
436
0
MVC-313F.jpg


MVC-314F.jpg


MVC-315F.jpg
 

Higgsy

Member
Mar 23, 2005
72
0
Thanks for the pics Rotoranch. When the valves are apart there is a small spring that goes inside the valves. One of the valve seems to have a small allen screw for adjustment but mine was loose so it would move in the slot in the valve. I am not sure were it should be when it's tightened. I'll try and get a picture on here soon.
 
Last edited:

Higgsy

Member
Mar 23, 2005
72
0
My book says 1 turn but I am sure they can be adjusted anywhere from 1/2 to 2 turns depending on the riding conditions.
 

monte

Member
Jun 16, 2004
34
0
i wonder if this applies to my 98 RMX250 (ADR model)? anyone know?
the service manual just says "turn the exhaust valve cap 180 degrees and install the bolts"

doesnt mention anything about having adjustment?

would i be able to turn it a little more to give at a little more top end? without damaging anything
 

RM_guy

Moderator
Damn Yankees
LIFETIME SPONSOR
Nov 21, 2000
7,045
208
North East USA
The stock tension setting changes from year to year, anywhere from 1/4 to 3/4 turns. The best bet is to find someone with a manual for your year bike. Too much tension and it delays opening and feels like the engine is running lean. Too loose and it either opens too soon and you loose some low end of they bounce from a hard landing or through rough terrain.

Adjusting them will not give you more power on the top or low end, they just change when the power band kicks in.
 

Higgsy

Member
Mar 23, 2005
72
0
Rotoranch do you notice much of a difference running it at 1/2 turn compared to 1 full turn? What kind of riding are you doing.
 
Jun 28, 2006
94
0
Higgsy said:
I cleaned the exhaust valve and installed them back into the cylinder. I noticed that the left side doesn't seem to open at the same time as the right side. Is that operating correctly? When opening the valves past half way the right side opens first then the left opens after. This is the first time I've had the valves apart so I don't know if this is normal.

Could there be excessive wear or burr holding or delaying the opening of the other valve? Do you have two springs on that power valve shaft? One is the (adjustable) tension spring. Doesn't the other spring have need to be originated a certain way on the shaft? Sorry but very limited on info for myself on this bike.
 

Rotorranch

Member
Feb 10, 2007
436
0
Higgsy said:
Rotoranch do you notice much of a difference running it at 1/2 turn compared to 1 full turn? What kind of riding are you doing.

It just seems to soften the hit a little.

I ride various types of stuff here. Tight woods, fire roads, old railroad beds, power liines, etc. Lately, mostly woods, and a little play time on mx track. Not racing anymore, but thinking about trying a SETRA hare scramble or two this season. Gotta find a class an old, slow guy can run. :whoa:

Rotor
 

Higgsy

Member
Mar 23, 2005
72
0
LOL that's the class I need to be in also.
I put the cylinder back on and fired up the bike. The engine seemed to run fine. I'll take it out for a rip soon and break it in.
 
Top Bottom