HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Kalar01

2008 YZ450 Valve adjustment help

48 posts in this topic

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

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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.

2 people like this

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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...

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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..

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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:

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0

  • Similar Content

    • By shawn denham
      i have a 2000 yz125 and i just took off the clutch case and i dont know the torque specs for the bolt. does anyone know ?
    • By Raven01
      Hi , I'm new here and I just purchased a spoke tourque wrench kit  "Excel (TWS-210ANS) 7-Piece Adjustable Spoke Torque Wrench Set" for my 2008 Yamaha  YZF450, the front spokes are smaller than the 6 that came with the bike and the rear spokes are larger than the 7 that came with the bike (I bought it New) Does any one know what sizes the front and rear spoke nipples are? I can still stop my order and seek the correct size somewhere. I find it lame that they gave me the wrong spoke wrench.
      Thanks in advance,
      Brent
       
       
    • By Zachhanus2
      Hey guys I'm looking to buy a bike again I'm currently saving up, prob gonna go on Craigslist should I go for a yz 125 or yz 250f, if I were to get a 250f I'd spend around 3300 is my budget, and goes for a 125 as well, I kno most of the differences but from any of your guys experience what would u say
    • By Gray4ACause
      Hello everyone, you wouldn't believe the brain dead mistake I made. So I installed my crank into the right side engine case on my 02 YZ426F last night. (Keyword Night) Then I proceeded to install the left side engine case onto the crank and trans with the Tusk Crank Installer. All is fine and dandy until I realized I didn't put any Yamabond on the case halves.  Now the left side case will not come back off the crank for the life of me. Note: The first time I split the cases the left side case came off without any hiccups. I am using the splitting tabs built into the case by the way. Does anyone have any tips? Also, why is the left side case being so stubborn this time? I hope I don't have to order a case splitter, those tabs saved me $70!
    • By Zachhanus2
      Hey guys I was wondering what bike I should get I havnt rode since I was in 7th grade but I had a kx 85 so I was experienced with riding I could pin the bike on tracks so I'm not completely new to riding now I'm 6,2 190 I was contemplating what bike to get, should I go with a yz 125 or should I go with a yzf450, I would never sell the 450 prob have it forever thank you tell me your opinions plz!!