2008 YZ450 Valve adjustment help

Hey,

I have looked in the common threads and done a few searches and can find no detailed tips or help on valve adjustment. I have the manual but I would like to see a few pictures with a lot more details. Anyone out there know where something like that could be found?

Thanks

Odds are that with an '08, you won't be needing to adjust the clearance in any case. Why not measure them first and go from there?

Ok, just pretend the pics are with it all on your bike:

Remove hoses and 2 allen bolts that hold the lid/gasket on:

DCFC0071-1.jpg

Checking clearances with cams in place (engine TDC) if everything checks out - put it back together at this point:

DCFC0079.jpg

If you are tight or at the tight end of OK then you need to continue on:

I place paint marks on the cam gear and chain so reinstalling is made easier, as well, tie a wire around your chain so it can be kept out of falling into the chain slot - try to keep a bit of tension on the chain so it does not bunch up at the bottom or else you may run into problems when putting it back together that will require you to pull your flywheel. After removing cams - fill the slot with a rag so you do not drop crap in there.

Remove cam chain tensioner, cam caps and cams to expose buckets (round plate you see):

DCFC0072.jpg

Use magnet to pull out buckets - most times the shim is stuck to the inside of the bucket:

DCFC0076-1.jpg

Read the shim size and cross reference to your chart in the manual then buy appropriately sized smaller shim to replace this one with so you end up at the big end of in spec.

nice write up Matt. :usa::thumbsup::smirk:

Thank you.

Odds are that with an '08, you won't be needing to adjust the clearance in any case. Why not measure them first and go from there?

I just pulled my '08 down for some maintenance (suspension service, regreasing all the bearings, etc) and it's first valve check at about 40 hours.

All the valves were in spec but they were on the lower end of the spec...for all I know it could be where they were at from the factory, but I adjusted them anyways to the upper end of the spec.

All the valves were in spec but they were on the lower end of the spec...

They are, in fact, built that way deliberately. It doesn't matter a lot, since the specified tolerance range is only .002" one way or other, but the tight side of the spec is preferable.
They are, in fact, built that way deliberately. It doesn't matter a lot, since the specified tolerance range is only .002" one way or other, but the tight side of the spec is preferable.

Really? Specifics? Not that I doubt you...just the never ending quest for knowledge...

When one runs at the tight side of the specs, impact between cam and lifter is reduced, extending valve train life. It is also technically correct to say that running tighter clearances extends the lift and duration of the cam timing, but when you're talking about .002", it's barely going to be measurable, much less noticeable.

Some move to the high side so that as wear occurs, the valves will settle farther into spec, rather than out on the low side, but in the YZF, clearance is so stable that this is not really necessary. Considering that more or less any wear at the valve itself means replacement, it doesn't matter much where they start from if they wear significantly.

Again, it's a pretty fine point considering the tolerance range is so small.

Thank you for your help. Looks like I have a project for this week end...

I checked my 08's valves at 1.5 hours and just last night at 10.2 hours and they are the same. Did not budge. Intakes are .004 and exhaust are .008, tight side of the spec but as Grey said thats how the factory builds them.

Hey Guys. I just bought a 2008 450 from a rider that rides pro. I have been talking to him off and on and he said that at 40hrs which is comming up real soon to replace the cam chain. He said that he gets 2 bikes a year and this bike was his race bike. I took it as (This is something I should do to keep the motor alive. Kinda like throwing me a bone.) Anyways, I ordered it and it is coming. My question is are Yamaha Cam Chains weak? I do not ride at the crazy competitive level the he did but this is definitly the nicest bike I have ever owned and want to keep it piping..

it's not that it really need to be be replaced just insurance. The yamaha cam chain isn't any more weak than any other brand but when it starts to stretch, it really hammers on your crank teeth and eventually ruins the crank. The cam chain is easy to replace and for 13 bucks or so, you can't beat the insurance.

OK awesome. Yeah I can't wait to get it done. I just wish there was someone around me with experience that could walk me through it the first time. I have read and read and read posts on the forum, just would be nice is all. I got the manual and I have you guys. I got it.

I just had to replace my timing chain after 86.4hrs. It started to make a slapping noise and after comparing it to the new chain, I was amazed at how much it stretched.

to matt4x4 and davcon thank you guys very much, i was looking for pics and vids for so long. :moon:

where can i find engine rebuilt vid now?

:busted:

OK awesome. Yeah I can't wait to get it done. I just wish there was someone around me with experience that could walk me through it the first time. I have read and read and read posts on the forum, just would be nice is all. I got the manual and I have you guys. I got it.
You read this one, then?

http://www.thumpertalk.com/forum/showthread.php?p=3150405#post3150405

It was written for an '05 or earlier model, so ignore the part about removing the stator plate.

Thanks Grey. I have read your post about a half dozen times. Awesome Write up man. :thinking: I am waiting on UPS now and it will probably be a few more days till I get it due to the Holidays.

O-MAN! Went riding today and I think something let go. I came over a jump and upon landing there was a pop and a wierd crazy sound coming from the engine. Needless to say I shut it off right away. It didn't lock up. I pushed it all the way back to the truck and put it on the stand. I shifted it through all of the gears moving the rear wheel to help engage. Tranny was fine. I loaded up and brought her home and pulled the valve cover to check the timing chain. It was there and the timing looked ok according to the HOTCAMS instal Video. I pulled the tensioner out (Was to it's max) and looked at the timing again. Looked like the exhaust was a little too far forward (Counterclockwise) compared to the intake so I slipped the gear back to allign them. It was good. I put it all back together and slowly kicked it over. There is something definitly wrong because I can hear a knocking sound. I just put it up and here I am. Any Clues? Should I think the Valves hit the piston? Should I take the head off? Man THis Sucks. I have only put 4-5 hours on this bike.

Does it have compression?

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