Exhaust Valves Extra Tight!

The bike I am working on is a 2006 CRF450R. I have never checked the valves on any bike before. I can just about do anything else on a bike. I went ahead and bought the HOT CAMS shim kit, appropriate feeler gauges and I already have a micrometer. I put the motor in top dead center and proceeded check intake valves and they look to be in spec at .005 and .006. But the exhaust valves are wayyyy tight at .003 for both exhaust valves. This is only about 10-15 hours since the last adjustment.

At the last adjustment, the mechanic told me the exhaust very tight and intakes were almost perfect.

Why are the exhaust valves tightening up so much? Only engine work that has been done is full exhaust, ported head and SS valves.

Your exhaust valves are wearing out. You will need to consider exhaust valve replacement before too much longer.

Exhaust valves aren't TI stock.

When you had the motor at TDC, are you sure that the cam lobes were pointing towards the rear of the bike?

yes I made sure I was at TDC on the compression stroke. I actually verified with a dial indicator on the piston through the spark plug hole. I think there was something fishy to begin with with this head anyways. I gotta find out if in fact there is SS valves and stock springs becuase from reading on here that is a no no. I will shim appropriately and jet check after every race weekend.

Yeah at this point all you can do is shim them and see what happens.

the biek comes stock with SS valves on the exhaust side....

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