2008 YZ450 Valve adjustment help

From Rocky Mountain

Tusk Flywheel Puller 24mm

Fits: 2008, YAMAHA, YZ450F

Regular: $19.99

Our price: $14.95

Part# 1179010001

Darnit ordered 10 minutes ago and JUST saw your post.:banana:

Oh well at least I gave TT Store my biz.

Anyone running the Tsubaki Cam Chain? That is some serious dough for a Cam Chain. Would it be worth the money? I am thinking probably not but I havent seen anyone talk about it yet.

2008 YZ450F,

Here is a tough one guys. Time for rebuild. Replaced piston, rings, pin, clips,cam chain and gaskets. Put it back together and clank! Sounds like piston is about to fly out of jug. Pulled it back down to find that all three intake valves are kissing the top of the piston. No damage but I've got to figure out why there were hitting. Now here is where it gets weird. The following measurements were before rebuild.

Sitting on the bike, far left intake was .13mm, center intake, .28mm, far right intake, .28mm.

Far left exhaust, .20mm, right exhaust .20mm.

Now, owners manual says intake tolerance .10 to .15- exhaust tolerance, .20 to .25

Took bike to shop to have them shim it for me. I measured just before install and they were .15 intake and .20 exhaust. I'm happy so here we go. Starts right off the bat but knocking like your head board while riding a two dollar lady of the night!

Where do I go now? Put it back to where it was before rebuild??

Anyone running the Tsubaki Cam Chain? That is some serious dough for a Cam Chain. Would it be worth the money? I am thinking probably not but I havent seen anyone talk about it yet.

I replace my cam chain every 40-45 hours, I've looked at the Tsubaki chain and a couple others that are almost 4X the cost of an OEM Yamaha chain but can't find any information/specs that show any sort of empirical data on either chain. Gray has posted before that the Pro-X cam chain and OEM Yamaha are both produced by Borgwarner I believe ?

For the difference in price and no available data showing one to be better than the other, I just replace my OEM chain more often. Once you have the tools (flywheel puller) it doesn't take more than 45 min to do if you're taking your time.

hey I did the valve adjustment on my 2008 Yz450F, the Valves were way over the max limits,, now I brought my bike in the tight spec, Intake 0.004" and exhaust 0.008"  put the bike back together, started her up, and sounded really smooth, and the next thing I know my head pipe is going red, after idling for 3 mins I shut it down.. waited until 5 mins, and tried to start it, started first kick. same thing happened again, the head pipe goes red.  


hey I did the valve adjustment on my 2008 Yz450F, the Valves were way over the max limits,, now I brought my bike in the tight spec, Intake 0.004" and exhaust 0.008"  put the bike back together, started her up, and sounded really smooth, and the next thing I know my head pipe is going red, after idling for 3 mins I shut it down.. waited until 5 mins, and tried to start it, started first kick. same thing happened again, the head pipe goes red.  

Sorry, I am new to this site, and not sure where to ask for help, as I thought it would be okay to do it here.

hey I did the valve adjustment on my 2008 Yz450F, the Valves were way over the max limits,, now I brought my bike in the tight spec, Intake 0.004" and exhaust 0.008"  put the bike back together, started her up, and sounded really smooth, and the next thing I know my head pipe is going red, after idling for 3 mins I shut it down.. waited until 5 mins, and tried to start it, started first kick. same thing happened again, the head pipe goes red.  

Sorry, I am new to this site, and not sure where to ask for help, as I thought it would be okay to do it here.

This has been discussed dozens of times and is in the FAQs at the top.  Its normal.  Don't let your bike sit and run that long though.

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