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about after how many hours Would i have to adjust the valves on a 04 YZ250f? or re-shim them?

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I cant answer your question, but someone else might be able to if you used the spell check when posting.

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I cant answer your question, but someone else might be able to if you used the spell check when posting.

I guess your program didnt recognize cant, when it should have been can't. Hmmm.

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I guess your program didnt recognize cant, when it should have been can't. Hmmm.

I guess yours did not recognize didnt when it should have been didn't or did not. Hmmm.

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There is no set time at which valves will need shimming, there's a lot of factors that play into valve wear. I'm still on my first set of valves on my 02 with lots and lots of hard hours and they're still in spec. Just check them every other oil change or so and know that when you need to shim, a valve job should be on your "to do list" very soon. Yamahas don't eat valves though, so don't worry about it.

p.s. If I left a punctuation mark out or something eat my balloon knot.

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I don't know either, but I did the first adjustment to my '01 250F in early '04, and I haven't had to adjust the '03 450 yet. In the 80 or so hours since the valve job in January, the 250 has not needed to be re-shimmed. :banghead:

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My 01 is about 60 hours now and the valves are in sped (but barely in spec!) They haven't moved in 10 hours of riding.

IMHO, checking the valves every other oil change is too much. I would say every year at the most check the valves. If they get close to out of spec, check it every half a year or so...

-Phill

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My 01 is about 60 hours now and the valves are in sped (but barely in spec!) They haven't moved in 10 hours of riding.

IMHO, checking the valves every other oil change is too much. I would say every year at the most check the valves. If they get close to out of spec, check it every half a year or so...

-Phill

Uhm, once a year is NOT enough. Let's say your valves go out of spec shortly after you check them, a year is far too long to ride on out of spec valves. You'll ruin your head and possibly ruin your motor if you end up breaking a valve.

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It is very unlikely that the valves will move so much in a short ammount of time.

Once the coating wears through on the face of the valve they wear at a rapid rate. If your valves were in spec for a long period of time, then get tight beyond specs, you will need a valve job shortly there after. Keep checking yours once a year and see what happens. Eventually you will be sorry you didn't check them more often.

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It is very unlikely that the valves will move so much in a short ammount of time.
That depends. The normal wear cycle with these is that they will stay at the same clearance for a very long period before they need their first adjustment. This will usually be followed by another fairly long interval until it needs another adjustment, depending on how much they moved the first time. Following that second one, they will tend to wear quite a bit more quickly, and once they have gone from around .15 to .20mm smaller than the original shim, they will no longer hold clearance for more than 6-10 hours. This is because at that point they will have worn through the hard coating on the valve face, and they should then be replaced.

During the first long phase of their life, I check the valves about 3-4 times a year, then more frequently as the wear cycle proceeds.

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Finally someone has gave me what I have been looking for...a good idea of when I need to do the first valve check on this 06 YZ250F. I have been reading post for what seems like 2 days, trying to figure out some sort of schedule and I believe I have a really good idea now. I installed an hour meter before the machine was cranked and all maintenance, oil changes at least will be based on hours run. I was hoping for a firm number like every 20 hours or 400 hours. So it looks like I need to check the valves about 3-4 times a year just to make sure all it OK and holding up. I will break it up to some hour meter reading according to use this winter and into next summer. I would like to have sufficient shims ready when I do the inspection incase I need to bring clearances in check. Do you guys recommend a buying a selection shims you may need from Yamaha or is there some company that sells a box with an assortment of quality shims that will do it for the 250F? I have never done this before but it ain't rocket sceince. FAQ looks pretty simple if you pay attention to detail. Thanks, there is a lot of good info here.

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I would wait and see if you need shims first, and then go to the shop and get them as needed. I checked my valves last week and needed to shim all 5 valves. I thought no big deal, I'll just run down to the shop the next day get them. Little did I know, but they were $8.50 each. Not sure if all shops are like this, but mine does 2 for 1 trades on shims, of course I didn't bring my old shims with me so I had to drive back home and grab them. Just my 2 cents

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I recently needed to reshim my 01 YZ250F and to my disgust found out that my local dealer wanted $10 per shim and no exchange program.

That would come to $50 to reshim each valve once. :confused:

And I'm potentially looking at re-shimming each valve three to four times before valve replacement this would cost me up to $200 just in shims and then when I replaced the valves I would need to reshim again and may not have the right sizes from ones already removed. :bonk:

Hot Cams sells a shim kit that I got for $69 with free ship on E-bay. 👍

I would reccomend buying a shim kit. Valve shimming will not be a one time event and will pay off in the long run unless your dealer has a much better deal. 👍

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If you can't find less expensive shims at one of the other 3 shops in South Dakota, a shim kit is the way to go. In my experience, the largest they are built with originally is in the 185-188 range. I mention that because Hot Cams offers a refill package containing 5 shims each of shims from 1.50 - 1.75mm, in .05 increments, for $36 (pn HCSHIM04) that will cover 95% of your reshim needs. If it turns out you need any 180's, you can either order them through TT OEM, or buy the next kit up for another $36. That kit would include shims from 190 to 205, which you will never use, and 185's, which you most likely won't need either, but it still might be cheaper in the long run. Finding out what's in there now may help you figure that out.

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Go into the mechanics area of your shop... if you bring in your shims they will most likely trade you the ones you need.

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On my son's 250F's, we replace top end every 20 hours and check valves at that time. We replace the timing chain every other top end. We will shim valves one time and next time need shimming we replace the valves.

We track everything with an hour meter and keep a log on the rear fender under the seat with a permanent marker.

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On my son's 250F's, we replace top end every 20 hours and check valves at that time. .

GAHH!!! :|

Are you serious you rebuild the thing every 20 hours, i thought they never needed rebuilds that often! $hi% i just bought a 250F 👍 Not cool!

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GAHH!!! :|

Are you serious you rebuild the thing every 20 hours, i thought they never needed rebuilds that often! $hi% i just bought a 250F 👍 Not cool!

They don't need servicing/replacing that often, they must race a lot and are just being cautious - nothing wrong with that if you can afford to do that.

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Two things i have found with shims. Alot of times the origianls are odd numbers, i.e. 177, 168. Where as the replacements are either 0s or 5s (170, 175) I have never found a mechanic that didnt want to trade when you explain to them you have hard to get off number shims. The other thing that worked on my 426 is take sand paper and rub the shim on it in a figure eight. You can do this and mike it down to the exact size you need assuming you need smaller, it worked for me. 👍

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