Valve Adjustment

[AAdavis]

Has anyone checked valve clearance on a new sled or adjusted one on a used one?

 

[Turboflash]

• Checking (measuring) it is one thing and not too hard to do (remove seat, loosen gas tank and slide it back, loosen pyramid steering post/chassis supports to be able to remove valve cover).
• Doing something about it is entirely another thing. Because IF you happen to want to change anyone of them, well it's a MAJOR job to do. It involves having to remove camshafts. To do that, you need to remove cam chain. To do that, you need to be able to access the cam chain tensioner which is located fairly low on the back side of the engine (right side) BEHIND and under the jackshaft. I have yet to find any tool or swivel or knuckle or anything that can access the 2 allen-head bolts that the tensioner in. You have to tilt the motor up on the backside to get at the bolts. To do that, you have to remove parts of the steering pyramid spars, remove the lower mount for the steering post (at the bottom) otherwise the engine hits the steering post. Then, you have to loosen the turbo mounting brace after you loosen or remove the exhaust pipe (between exhaust manifold and turbo), remove the intake plenum crossover tube from air box to turbo, etc, etc.

This all necessary just so you can tilt the engine up in back (pivot on from motor mount bolts) so you can get the cam chain tensioner out. Then you can get the cams out (after very careful measuring) so you can remove whichever tappets you need and change the shim. Then, you have to put cams back in and re-check everything. Once you're pleased with all the clearances, then carefully re-time the cams with the crank and install cam chain and then put it all back together.

You might be wondering how I know? Because I've had to take the head off my 998 TWICE. And taking the head off is even more work than "just" checking valve clearance and/or re-shimming.

If anyone has an easier faster simpler way of doing this, I'd love to hear it. Putting that cam chain tensioner where they did is a disaster from a serviceability perspective. No wonder they use an "auto-adjust" hydraulic tensioner. It works very well IMO. It keeps the cam chain tension just right.

All that said, the official service manual says to "check" valve clearances every 25,000 miles. So, I've got a long ways to go until I get to anything close to that mileage, thank heaven!!

 

[AAdavis]

• Checking (measuring) it is one thing and not too hard to do (remove seat, loosen gas tank and slide it back, loosen pyramid steering post/chassis supports to be able to remove valve cover).
• Doing something about it is entirely another thing. Because IF you happen to want to change anyone of them, well it's a MAJOR job to do. It involves having to remove camshafts. To do that, you need to remove cam chain. To do that, you need to be able to access the cam chain tensioner which is located fairly low on the back side of the engine (right side) BEHIND and under the jackshaft. I have yet to find any tool or swivel or knuckle or anything that can access the 2 allen-head bolts that the tensioner in. You have to tilt the motor up on the backside to get at the bolts. To do that, you have to remove parts of the steering pyramid spars, remove the lower mount for the steering post (at the bottom) otherwise the engine hits the steering post. Then, you have to loosen the turbo mounting brace after you loosen or remove the exhaust pipe (between exhaust manifold and turbo), remove the intake plenum crossover tube from air box to turbo, etc, etc.

This all necessary just so you can tilt the engine up in back (pivot on from motor mount bolts) so you can get the cam chain tensioner out. Then you can get the cams out (after very careful measuring) so you can remove whichever tappets you need and change the shim. Then, you have to put cams back in and re-check everything. Once you're pleased with all the clearances, then carefully re-time the cams with the crank and install cam chain and then put it all back together.

You might be wondering how I know? Because I've had to take the head off my 998 TWICE. And taking the head off is even more work than "just" checking valve clearance and/or re-shimming.

If anyone has an easier faster simpler way of doing this, I'd love to hear it. Putting that cam chain tensioner where they did is a disaster from a serviceability perspective. No wonder they use an "auto-adjust" hydraulic tensioner. It works very well IMO. It keeps the cam chain tension just right.

All that said, the official service manual says to "check" valve clearances every 25,000 miles. So, I've got a long ways to go until I get to anything close to that mileage, thank heaven!!

So coming from a lifetime of motorcycles I have been adjusting valves and degreeing cams on DOHC motors all my life. I always like to check valves on a new motor to know where I am starting from and how much they change. Yamaha motorcycles valves have a reputation for being very stable. So 25000 miles is a realistic service check. This all assumes that they are right from the factory. I just took my new SRX apart tonight to start modding it. It looks like it would be quite a job to pull the cams out. In fact it looks like it would just be easier to pull the motor and then do it and degree the cams while I was at it. It would be a nice summer project. So I would like to know from those who have checked what did you find?

 

[Turboflash]

So coming from a lifetime of motorcycles I have been adjusting valves and degreeing cams on DOHC motors all my life. I always like to check valves on a new motor to know where I am starting from and how much they change. Yamaha motorcycles valves have a reputation for being very stable. So 25000 miles is a realistic service check. This all assumes that they are right from the factory. I just took my new SRX apart tonight to start modding it. It looks like it would be quite a job to pull the cams out. In fact it looks like it would just be easier to pull the motor and then do it and degree the cams while I was at it. It would be a nice summer project. So I would like to know from those who have checked what did you find?

Agree, it probably wouldn't be any more work to just pull the engine. I thought that more than once. I installed ARP head studs while I was at it since I'm running 19 lbs of boost.
Sounds like you are a true big-time engine builder. It's not that it's difficult to get cams out, etc while engine is in chassis, but it's just takes time. Like you said, a good summer project. For what it's worth, when I checked my valve clearances, they were all right on nominal from factory. I had to move all my valves and cams to a new head (factory head was cracked!!!) and re-check, re-shim them all. Of course, its easier to do if the heads are off since you don't have to be concerned with valves hitting pistons, cam timing, etc.

 

[74Nitro]

I tore into a 2018 today that recently came in with no compression on pto cylinder.
The problem turned out to be that the spring seat was never there from the factory.
Eventually the spring wore down into the head then things came apart.

 

[fatchance]

I tore into a 2018 today that recently came in with no compression on pto cylinder.
The problem turned out to be that the spring seat was never there from the factory.
Eventually the spring wore down into the head then things came apart.

Did the owner call about warranty coverage? Seems like something like this if it's well documented they would have a chance at getting some help with the cost.

 

[74Nitro]

Did the owner call about warranty coverage? Seems like something like this if it's well documented they would have a chance at getting some help with the cost.

Seven years old and has a tune. Zero chance.
Under 5000kms.