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
neevothespaniel

05 YZ450F Valve Clearances

5 posts in this topic

This is a copy of a thread I started in the General section. On thinking I realised it should have been here. So...

Hello everyone,

Just picked up my first bike on Saturday, very happy to say the least. I have spent the weekend taking it apart to make sure everything is working ok and in good condition.

The bike is an 05 and has about 10 genuine hours on it. My question pertains to the valve clearances.

The guy I bought it off didn't have the clearances checked due to the amount of hours on the bike. I thought I would check them before I started using the bike and here's what I got from a cold engine:

Intakes: 8mm / 10mm / 10mm (spec range 10mm - 15mm)

Exhausts: 15mm / 18mm (spec range 17mm - 22mm)

Looks like I need to do some shimming.

I just wanted to check that this seemed right as its my first time doing this kind of thing. Do valves "bed in" when the bike is fairly fresh or are they moving too soon?

Also is there any way of knowing what shim's are in the motor at the moment or do I have to wait until I have them out to figure out what new shims I will need?

Your thoughts would be appreciated

Share this post


Link to post
Share on other sites
Do valves "bed in" when the bike is fairly fresh or are they moving too soon?

Also is there any way of knowing what shim's are in the motor at the moment or do I have to wait until I have them out to figure out what new shims I will need?

They don't usually bed in very much, if at all, but it does happen. The thing to do now is to correct them, and then recheck in another 5-10 to see if they have stabilized at that setting.

As to the existing shim sizes, there's no way to know what they are without looking, except that they will be somewhere between 175 and 190. Don't be surprised at finding shims marked with odd numbers such as 188. These are factory build shims, used at the factory to more precisely set clearances to exactly where they want. Actually, although such shims are not available from either Yamaha or most aftermarket sources, you can get shims in increments of .025mm, instead of the usual .05, by buying them for a CRF450 at a Honda shop. Just be sure the OD of the shim is 9.48mm.

Share this post


Link to post
Share on other sites

Well I took my piece of paper to the bike shop yesterday to get me a couple of shims. I my haste I forgot to check the table to see what shim size I needed to move to.

"Thats no problem" I thought to myself, "I can do maths!!! I will just work it out". Well my genius mind got working and I got the shims. Got home and installed them, using my brand new torque wrench, got it all back and decided to recheck the clearance and to my surprise the clearances were tighter :bonk:

This wanna be mechanic had worked out the shim sizes the wrong way :ride:

Oh well, its a learning curve. At least I will be familiar with pulling the cams out etc :)

I do have a question though. I bought an additive from the bike store that you put into your fuel. Its supposed to replace the lead that has now been taken out of the fuel. Does anyone have experience with this kind of stuff and does it really protect the valves?

Share this post


Link to post
Share on other sites

Yeeeehaaaaaaaa!! Just finished my first ever valve clearance check and shim change :)

Mucked it up a couple of times by firstly not using the tables and going up in size instead of down. Then I put the lifters back in on top of the new shims to find I had forgotton to take the old shims out of the lifters :ride:

But thats why you double check at the end I suppose. Just went to fire the thing up to make sure that it runs and it started first kick!!

Woo Hoo. For anyone that is too afraid to do this I suggest you have a go. The manual is easy to follow and as long as you have the right tools then you are set to go. Plus as an added bonus you save a bit for not taking it to the store (just have to minus lots for all the tools you have had to buy).

Share this post


Link to post
Share on other sites
Yeeeehaaaaaaaa!! Just finished my first ever valve clearance check and shim change :)

Mucked it up a couple of times by firstly not using the tables and going up in size instead of down. Then I put the lifters back in on top of the new shims to find I had forgotton to take the old shims out of the lifters :ride:

But thats why you double check at the end I suppose. Just went to fire the thing up to make sure that it runs and it started first kick!!

Woo Hoo. For anyone that is too afraid to do this I suggest you have a go. The manual is easy to follow and as long as you have the right tools then you are set to go. Plus as an added bonus you save a bit for not taking it to the store (just have to minus lots for all the tools you have had to buy).

It's also kind of like raising children: "nobody will care for your kids more than you".......

Nicely done! I do all my own work (minus suspension), and because of that fact there is never any surprises about how my bikes run.

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