Jump to content
Sign in to follow this  

My valve adjustment story

Recommended Posts

So yesterday it finally happened after 2 years, valves out of spec.

Intake: Left->0.07mm (186 shim) Middle->0.07mm (180) Right->0.07mm (185)

Exhaust: Left->0.15mm (174) Right->0.15mm (175)

Well at least the tightening was consistent. So now I need 2-170 shims and 1-180 shim to get them all into spec. Here is where my nice and easy Saturday morning takes a turn. I go to the local Yamaha shop and the parts guy looks at me like I'm from outer space. When I ask if they have these shims available, he has no idea what I'm talking about. So he gets the owner of the shop, "we don't carry shims in stock." I ask the parts guy, "don't you work on thumpers?" He looks at me and says "to tell you the truth we only really work on 2 strokes." Now I'm looking around and in the front are 2 WR250F's, a 250F, a 450F, and a WR450F for sale! He then offers to order them for me, but he says if you order them, they come in packages of 5 at $6 each! $60 for 3 shims needed! So, I thank him for his time and leave.

I call the Yamaha shop where I bought my bike from, same story, we don't carry them in stock and no, we don't have a trade in policy. But, I'm talking to one of the service guys and he directs me to the local race shop. I call them and they have the shims I need and a trade in policy! Thank God!

One good thing that came of this is that since I couldn't finish my valve adjustment, I have to go on Monday to pick up the shims, I decided to re-grease my steering head. I don't know if this has been suggested before, but I was looking at the OEM rear shock spring adjuster that came with the bike and it looked like it would fit the steering ring nut. Violla! It fits perfect and works great. No need to hit it with a chisel and hammer like suggested in the FAQ section. Swingarm to be done next.

Is there a shim kit available? I know I have read about it here on the forum, but I haven't been able to find a seller. Maybe we can all get together here and start a shim exchange?????

Thanks for listening :cry:

Share this post


Link to post
Share on other sites

I think he's wrong about the packaging. All the shims I've purchased came sealed, one to a pack, with the part number tag indicating a quantity of one. It is annoying to have to order what seems like a commonly used service part, but the actually don't get used that much, and the techs in the service department quite often have their own kits, so they don't pull from the parts department's inventory.

The same shop was pretty stocked up with shims for Hondas for some reason... :cry:

I don't know the source for the shim kit either, but maybe somebody will come a long and fix that for us. :cry:

Share this post


Link to post
Share on other sites

"Hot Cams" has nice shim kits at an affordable price. The only issue I've had is they are a little shy on the larger thickness shims that you need for Honda CRF exhaust side. The larger shim kit for the 426/450's is a "2 Pack". Get the kits, you'll never need to not finish a job that you started and you can always start your own "trade in program" and or start your own valve adjusting side business. :cry:

Share this post


Link to post
Share on other sites

The problem with performing unecessary steps is that it creates yet another possibility for something to go wrong. If it isn't in the way, leave it alone.:cry:

Share this post


Link to post
Share on other sites

my dealer gave me the wrong shims at first. The diameter was way too big. What's worse is I went in the next day and the mechanic (shims not in parts department) told me I was mistaken. I then showed him the correct size and he shut up. At least my dealer has a trade in policy.

Share this post


Link to post
Share on other sites
get them here. Come in packs of 1! http://www.yamahaaccy.com/parts.aspx

and

"Hot Cams" has nice shim kits at an affordable price. The only issue I've had is they are a little shy on the larger thickness shims that you need for Honda CRF exhaust side. The larger shim kit for the 426/450's is a "2 Pack". Get the kits, you'll never need to not finish a job that you started and you can always start your own "trade in program" and or start your own valve adjusting side business.

Thanks guys for the info. I actually went to my local race shop and they had a large assortment of shims for only $4 a piece. They had shims in all sorts of sizes, not just the 0.05mm incremented ones us mere mortals can get. If anyone is in the Chicago area, I highly recommend 4 and 6 Racing in Skokie, IL. Good guys,very knowledgable, and a nice big shop. Just buying 3 shims and the valve guy talked my ear off for an hour. It's allways fun going into a shop with real enthusiatic people working who love their jobs.

Cheers :cry:

Share this post


Link to post
Share on other sites

I don't know where you live in illionois, but if you're close to st. louis, i know there ia a shop that carries a dozen of each shim made, sell them individually. I don't think that they take trade ins though.

Share this post


Link to post
Share on other sites

I am in the process of rebuilding a 2003 YZ250F and had all 3 intake valves tight. When I started the anal questioning as to why these valves are tight, the obvious answer is the valves are no longer flat on the mating surface with the head surface. After pulling the head off, all 3 intake valves had mashed a bit, which was just enough to bring my valve clearance out of spec. So in talking about valve adjustments, how long do you go before changing out the valves which is the real problem? Or do you just keep making adjustments until it really goes bad? I had 2 years on this motor with no problems. Just changed the oil alot.

Share this post


Link to post
Share on other sites

511Dean,

The answer to your question seems to vary depending on who you ask. From what I have been able to gather, the 1st time you make an adjustment on your valves, you are adjusting for the initial "settling in" of your valves/springs,etc. A lot has to due with how you abuse your engine. Some seem to be luckier (those who have never needed adjusting) then others. Thereafter, all adjustments are being made to counter "normal" degradation of the valves( tuliping,stretching,etc). Again dependent on how you abuse your engine. If you are making adjustments often then it is not an actual number or percentage you need to look for, but just the fact you are decreasing shim size so often indicates excessive wear in the valves. Some would say that a 10% reduction from original shim size is when you should be thinking seriously of new valves. So if your original shim is 1.75mm (a 175 shim) you could go down to a 1.58mm (1.75-(1.75x10%)=0.158) shim (a 160 shim which is rounded up) before changing your valves. If anyone out there has the definitive answer, please chime in.

Cheers :cry:

Share this post


Link to post
Share on other sites

Shims and buckets are the highest performance configuration possible......But, nothing is free, and they are a pain in the arse, or worse....

However, I live in So Cal, so my dealer is 4 miles away and has a no charge trade in policy for Yamaha shims. I've never spent more than an afternoon doing a valve adjustment. :cry: BUT, I did think that if I had to order them, it would drive me nuts...... Not that I far form it now, but......

RH

Share this post


Link to post
Share on other sites

I have had my bike for a year.Checked the valves last night and they all were within spec. Checked my friends though and his were way too tight. It's weird how they work.

Share this post


Link to post
Share on other sites
...the 1st time you make an adjustment on your valves, you are adjusting for the initial "settling in" of your valves/springs,etc. A lot has to due with how you abuse your engine. Some seem to be luckier (those who have never needed adjusting) then others.
That's pretty correct. What it really depends on most is how well the valves and seats matched up with each other when they left the factory. The more perfectly seated they are, the less "wear in", or settling there will be.
Thereafter, all adjustments are being made to counter "normal" degradation of the valves (tuliping,stretching,etc). If you are making adjustments often then it is not an actual number or percentage you need to look for, but just the fact you are decreasing shim size so often indicates excessive wear in the valves.
Right again. Mostly. This indicates the Nitride coating has been worn through. It holds up better on Yamahas than on any other MX four-stroke, just because the valves and the coating are both of a higher quality. But, once it's worn through, wear accelerates. Titanium is a lot of very wonderful things, but it isn't all that hard. In truth, the valves will very rarely stretch or tulip (a condition in which the center of the valve head is pulled up by the stem), that would be working against some of Titanium's strong points. Mostly, it's just wear at the faces once the hard coating is gone.
Some would say that a 10% reduction from original shim size is when you should be thinking seriously of new valves. So if your original shim is 1.75mm (a 175 shim) you could go down to a 1.58mm (1.75-(1.75x10%)=0.158) shim (a 160 shim which is rounded up) before changing your valves. If anyone out there has the definitive answer, please chime in.

The amount that a valve recedes into the head is about 1.4 times the amount of actual wear at the valve/seat due to the seat being at 45 degrees to the stem. So that would mean that .15 mm reduction in shim size is the result of not quite .11mm wear at the valve face. That's .004 inch. I don't imagine that the Ti Nitride coating is a great deal thicker than that. But whether it is or isn't, a sudden increase in the rate of clearance loss is a very clear signal that it's time for new valves.

:)

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

Reply with:

Sign in to follow this  

×