Adjusting the Control Flap

I'm doing a top end on my 1998 125SX. My repair manual has a section that describes how to adjust the control flap. Is this necessary when doing a top end or is this only critical when the bottom end has been dismantled?

Thanks for the help,


only needs to be done if the adjustment is changed. That can be because you turned the axles or cuz the axles lock plates strip and allow the axles to turn on their own. Normally this is adjusted when you take the PV apart to clean it.

I should have mentioned that I did indeed clean the PV. So, I guess that means I need to do the adjustment.

Any tips on how to do it without the fancy hook type depth gauge shown in my manual?

I look into the bore and thru the exhaust port. I center the flapper in the port with the axles as best I can, checking for drag or hitting the sides. The axles should not be tight, they need to let the flapper move freely. Not too loose either, just right.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now