A local race shop has a z400 with a 440 kit in it. Port job and all the race goodies. After racing it hard it is siezing the cam in the head and stretching/jumping the chain. Aparently suzuki didnt think it was nesasary to put ball bearings on the camshafts and lets them ride in an aluminum journal(bad idea) Has anyone come out with a needle bearing kit to fix this. Did the new z get an update? Even brass bushings would be a vast improvment. I remember the old 350x had a similar system.

 

Rotax is good for that too.

 

My kfx-400 is doing that right now. ITs so fustrating. THe cam chain i think is stretched out, i can hear it slappen and i have a hybusa cam chain tensioner which is almost all the way in. I put that cam chain Tensioner because its manual adjusting. Take mine in today to see what can be done. The noise is hurt full to the ears.

 

I see a lot of people messing with stronger chains and tensioners but the core problem seems to be the cam journals tightening up on the cam when the engine gets really hot . He's tried synthetic oil but still no luck.

 

Brought mine in today and my guy will have the engine into two peices by tuesday. Replacing the cam chain. What can i do to prevent this again. Do you think its from having a +1000 rpm cdi. What do ya suggest.

 

my bro in law has a bunch of mods on his z including the cdi box and hasn't had any trouble with his cam chain. what is the first indication of it not working properly?

 

It's deceiving because its sounds like valves tapping, but its the cam chain slappen against the side of the engine.

 

Well this one actually locked up the motor while racing after a few minutes. The head is heavily ported and there is less mass to absorb the heat now. Aparently the journals are swelling up from the heat and tightening up on the cams. After it cools down it will turn over ok but the chain is stretched out or skipped the crank gear. Simple ball or needle bearings would take care of it .

 

Without extensive machine work and fitting it, you may need to simply add 1/4 or 1/2 thousandths clearance to the journal. Also have you thought of possibly grooving the journal or maybe even adding or enlarging the oil holes?

 

Wouldnt that just reduce the area that the cam has to turn on and cause it to wear faster? Thats my thoughts anyways, for what its worth.