Timing Chain & Cams

Having problems getting marks to alighn

and look right.

recently had the top end done and 10 minutes

into the next ride it bent 3 intake valves.

(supposidly the intake cam stopped )

the shop that did the top end repaired everything and the bike runs but not like before, so i pulled it apart to see if they had it YZ timed like i had it before.

I have it apart right now and it seems as though the marks will not line up just right

and the chain appears to ride high on the cam sprockets ( can see light/distance between valley of sprocket and chain and even a little space between tip of teeth and chain ) Is this normal?

need to know if when on the I mark does the intake cam sprocket punch mark sit above the head right accross from the other one as in

9:00 strait accross from 3:00 perpindicular

to the head or 3:00 punch mark right leval with head and 9:00 punch mark kind of up a

1/4 inch or so.

Please Help have Race in 6 days, Thanks

VERY weird!!

Sounds as if they have the wrong cam chain in there.. either that or your cam sprocket teeth are very warn.

How olds the bike??

My guesses anyway!! :):D



**Ride it like you Stole it!**

Matt Porritt

99 YZ400F

Vist the Rubber Chicken Racing Online Shop

Discounts for ThumperTalk members.

when i went to YZ timing i had the same trouble, but with a little help i got it right. this is the standard YZ timing below.

with the flywheel dot lined up with the marker through the flywheel cover hole.

my exhaust cam was tilted clockwise so that the left punch mark was lining up one rivet dot above the head. the other (r/hand) dot is slightly hidden below the top edge of the head.

my inlet cam sits again tilted slightly clockwise. the right hand dot is absolutely in line with the top of the head. the left hand dot sits proud of the head by the width of one tooth.

check that you have the 12 pin gap as shown in the technical section for YZ timing.

good luck.


[This message has been edited by Taffy (edited 10-17-2000).]

My Bike is A 99 with 3000 miles on it.

What exatly do you meen by the 12 tooth gap.

Thanks for the info so far.

[This message has been edited by Rich Clarke (edited 10-16-2000).]

[This message has been edited by Rich Clarke (edited 10-16-2000).]


Take a close look at your cam chain. Notice the PINS that connect the links. You want 12 pins between the punch marks on the cams.

quite right kev, but i got the rest right didn't i? so it's pins & not teeth.


Can the cam-chain stretch, if so when should it be replaced according to the manual?

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