My comments on the "check valves" common question

[Polar_Bus]

I have been involved with the YZF's since '01. I work for a Yamaha dealer, so I talk with tons of other YZF owners and racers. I just wan't to comment to everyone out there who is paranoid about checking, (or not checking) their fresh YZF valve clearences. I can say from the 4 years I have been around them I have yet to sell a set of valve shims to a customer from valves being out of spec. I have gotten feedback on 2 cases of needing to re-shim. Guy #1) put in a set of Hot Cams, years ago. (I have since been getting feedback, there is no need to re-shim with current Hot Cam swaps). Guy #2 had to re shim after about 10 hours of run time, a month later, he realized he had a bad cam, for whatever reason, also wiped out his cyl. head. Take this post as you like. With my WR, my valves were in perfect spec at 10 hours, and within perfect spec 5000 mi. later, when I checked them last month. I recently completely replaced my buddies YA250F cyl head. I used the old valve train, and was VERY curious how the valve clearences would pan out, they ended up again, right in spec. I'ts proven clear to me Yamaha has a tight wrap on their machining tolerences. IMO if you check the valves on your newer 250F, and they are out of spec, you better check things over REAL close, because I bet you have an issue somewhere in the valvetrain. (strictly my opinions)

Rich

[grayracer513]

It's really a very simple thing; a good design executed well, using materials of at least adequate quality. No shortcuts. It isn't rocket science at all, and neither is it patent protected, so I, for the life of me, can't figure out why the other makes can't or won't do it. It's just a matter of using the materials you know you need for the job you're doing, and that's it.

When I did a valve adjustment on my '01, it was the first one it had ever had done to it. It was also in the summer of '04. I had to do a valve job on it this last January, but the clearance hasn't changed since. My '03 YZ450 has never needed a reshim.

[wannabe_bubba_259]

It's really a very simple thing; a good design executed well, using materials of at least adequate quality. No shortcuts. It isn't rocket science at all, and neither is it patent protected, so I, for the life of me, can't figure out why the other makes can't or won't do it. It's just a matter of using the materials you know you need for the job you're doing, and that's it.

When I did a valve adjustment on my '01, it was the first one it had ever had done to it. It was also in the summer of '04. I had to do a valve job on it this last January, but the clearance hasn't changed since. My '03 YZ450 has never needed a reshim.

Did you have to have any work done to the seats?

[grayracer513]

Did you have to have any work done to the seats?

Of course. They were refinished by the machine shop doing the job. That's how it's done right.

[HugeSwapper]

I have been involved with the YZF's since '01. I work for a Yamaha dealer, so I talk with tons of other YZF owners and racers. I just wan't to comment to everyone out there who is paranoid about checking, (or not checking) their fresh YZF valve clearences. I can say from the 4 years I have been around them I have yet to sell a set of valve shims to a customer from valves being out of spec. I have gotten feedback on 2 cases of needing to re-shim. Guy #1) put in a set of Hot Cams, years ago. (I have since been getting feedback, there is no need to re-shim with current Hot Cam swaps). Guy #2 had to re shim after about 10 hours of run time, a month later, he realized he had a bad cam, for whatever reason, also wiped out his cyl. head. Take this post as you like. With my WR, my valves were in perfect spec at 10 hours, and within perfect spec 5000 mi. later, when I checked them last month. I recently completely replaced my buddies YA250F cyl head. I used the old valve train, and was VERY curious how the valve clearences would pan out, they ended up again, right in spec. I'ts proven clear to me Yamaha has a tight wrap on their machining tolerences. IMO if you check the valves on your newer 250F, and they are out of spec, you better check things over REAL close, because I bet you have an issue somewhere in the valvetrain. (strictly my opinions)

Rich

Appreciate your insight. Thanks

[devore_80]

I have an 02 bought used. Don't know if the guy before me checked them. I want to go through it prob in a week or two before the indoor season starts. I know I should search this up but limited on time. What tools do I need to tell if they are in spec and if they are not what tools to fix. Thanks

[grayracer513]

What tools do I need to tell if they are in spec and if they are not what tools to fix. Thanks

I would explain it to you, but I'm limited on time.

http://www.thumperfaq.com/valves.htm

[warrior86]

yes, thank you

[Polar_Bus]

I have an 02 bought used. Don't know if the guy before me checked them. I want to go through it prob in a week or two before the indoor season starts. I know I should search this up but limited on time. What tools do I need to tell if they are in spec and if they are not what tools to fix. Thanks

Very simple to check, more in-depth to fix out of spec valves. To check you will need a small feeler guage. You will most likely have to trim the feelers so they are about .250" wide (it's a VERY narrow acess opening to get the the cam buckets). rotate the flywheel until the cam lobe tip is completely pointing in the opposite direction away from the valve. Measure the clearence between the cam lobe, and the valve bucket. When a certain thickness feeler just "slips in" read that thickness. Always start on the thick side of the spec. If your final thickness is .003", start with a .006" feeler, and work your way incramentally thinner.

Rich

[Matty05]

I have an 02 bought used. Don't know if the guy before me checked them. I want to go through it prob in a week or two before the indoor season starts. I know I should search this up but limited on time. What tools do I need to tell if they are in spec and if they are not what tools to fix. Thanks

Your manual is your best friend!

[devore_80]

Thanks guys,(I wish I had the manual)

[johnk408]

3 years on mine, checked regularly, always in check. Although, I think a lot has to do with maintenance and not riding at 13000 rpm all the time.

[barton]

You can download the manual here

http://www.thumperfaq.com/oemmanuals.htm

[uhoh7]

Unfortuneatly, I believed the advice on top. So I let my 04 go a bit too long and as a result I have an intake which has gotten hot and will eventually have to be replaced.

If I had caught it right away.....

[Polar_Bus]

Unfortuneatly, I believed the advice on top. So I let my 04 go a bit too long and as a result I have an intake which has gotten hot and will eventually have to be replaced.

If I had caught it right away.....

OK, this makes NO sense at all. An intake valve getting "too hot"? What exactly does this mean? (and is now the intake valve is out of tolerence?). Sorry, this doesn't happen. As a result you are going to "eventually" replace the valve??? Ignoring a small issue now, WILL take out every mating component later, so instead of $100 to fix, now you spend $600

[Ambluemax]

All I know is that my 02 has tigh exhaust and intake clearances with stock shims. I don't know what the previous owners did to it, but she's sure messed up now

[barton]

The way I understand it is that when valves don't fully seat, they can't dissipate their heat to the cylinder head. Thus a "tight" valve's clearances might progress to the point that it can't be seated. Being unable to shed heat it gets very hot, which may change the valves metallurgy (it probably gets annealed which makes steel softer) and it is more prone to failure, even after re-shimming. That's what he means by "too hot".

This is probably an incomplete picture of what happens, but the upshot is that you don't want to get your valves in this condition. If it did happen to any of my valves, I'd replace it immediately, and probably the spring as well.

Yes, Yamaha valves are reliable, but NO this doesn't mean you shouldn't check them regularly.

[uhoh7]

OK, this makes NO sense at all. An intake valve getting "too hot"? What exactly does this mean? (and is now the intake valve is out of tolerence?). Sorry, this doesn't happen. As a result you are going to "eventually" replace the valve??? Ignoring a small issue now, WILL take out every mating component later, so instead of $100 to fix, now you spend $600

If you don't understand how a tight valve can get hot....well you don't know much...and should not give advice on four stroke motors with titanium valves....which are much more sensitive to heat than stainless steel valves.

As to the tolerance of the valve, yes it is shimed correctly now. But because I waited too long the "CHECK THE VALVES" in the first place the valve is moving and has had to be shimmed twice in 2 months, with only enough room for one more adjustment.

SO I would say your advice is misleading, and could result in ruined motors, for those who never bother to "CHECK THE VALVES".

As any student of the 250F motor knows: the titanium valves are the weak link, and should be attended to. If they are in spec: GREAT.

But if you bike has bog or is hard to start cold CHECK THE VALVES or be prepared to pay the price.

[ARin]

if your bike was starting hard, or bogging, then its your fault you let them go so long.

[Polar_Bus]

If you don't understand how a tight valve can get hot....well you don't know much...and should not give advice on four stroke motors with titanium valves....which are much more sensitive to heat than stainless steel valves.

As to the tolerance of the valve, yes it is shimed correctly now. But because I waited too long the "CHECK THE VALVES" in the first place the valve is moving and has had to be shimmed twice in 2 months, with only enough room for one more adjustment.

SO I would say your advice is misleading, and could result in ruined motors, for those who never bother to "CHECK THE VALVES".

As any student of the 250F motor knows: the titanium valves are the weak link, and should be attended to. If they are in spec: GREAT.

But if you bike has bog or is hard to start cold CHECK THE VALVES or be prepared to pay the price.

Dude, I have raced, and wrenched motorcross, and automibile circle track for over 22 years, so don't dump on my engine capebilities, (or lack of). I am not dumping on yours. I also do CNC machining and work with Titanium bar stock on a daily basis. You claim of Ti being "more sensitive to heat" than stainless is so friggin a$$ backwards....... Ti is 20 times more warpage tolerant to extreme heat than ANY other metal. Ti is also superior is DISPELLING heat. Ti is also posseses superior abrasive resistant qualities. Also I NEVER once said never to check your valves. All I did was lay out my comments on the whole issue of people in panic from not checking their valves, and ones who think they need to be checked on a monthly basis. My whole simple point of my original post was if you check your valves and they are out of spec, you most likely have a more serious issue in your valvetrain, EXACTLY as YOU do.