HELP... Valve Shim


13 replies to this topic
  • Cooksend

Posted May 11, 2012 - 03:31 AM

#1

Hey guys and gals. I took it upon myself to try to shim the valves last night on my 2003 WR450 and have a few questions. Things went smooth up until reassembly! Also if you take a look at the pic I don't believe the marks on the bucket are suppos to be there? You can see the pin in the cam sticking out and that is what is causing the marking on the bucket. Hopefully you can understand my questions below!

1. when finding TDC aligning marks in site window while turning the crank did not match what the dimples on the cam gears were showing. I did check clearance with both and found it to be the same.

2. upon inspection I found marking on the exhaust left side bucket that came from the pin in the camshaft (shown in the picture).

3. After shimming to match specs and reassembly of the cam cover I once again checked valve clearance and the valve with dimples on the bucket was within spec at .23 and now after reassembly is only at .15???

4. I decided to put it back together and see if it would start and how it would run. The motor is extremely tight and does not want to turn over freely. It will loosen up for a short time every other revolution but tighten back up again and did not start (I am thinking that was a good thing with the motor spinning tight.

I decided it was time to tackle the project as I have only checke clearance twice on the bike and it now has 6,000 miles (dual sported). This time only two valves were out of clearance and both were a bit tighter than spec. The other 3 were right at the low side of spec. Lately it has been getting a bit harder to start when hot and has been puffing a bit of smoke on hard accelleration. Also others following me have been complaining of the smell. I am a salesman not a technician so I am hoping for a bit of help... Oh yeah don't hold the salesman thing against me!

Posted Image

  • bg10459

Posted May 11, 2012 - 04:13 AM

#2

The marks on the bucket are normal. All the buckets spin, that one also gets hit by the decomp pin.
You're supposed to check clearance with cam caps properly torqued. Maybe I misunderstood, but if it changed after assembly, that's the number you should be working with. You'll need to re-shim that valve.
There is more than one timing mark on the flywheel. If you didn't remove both cams at the same time, it should still be timed right. Line the cam marks up with the top surface of the head and see what mark show in the window. You should be close. Maybe your timing chain is stretched, though. An 03 that hasn't had a timing chain done probably could use a new one. They're pretty cheap, but could be a pain to do. My flywheel was siezed to the crank and I had to cut it off. Fortunately, I was doing a total rebuild, anyway.

Edited by bg10459, May 11, 2012 - 04:15 AM.


  • Cooksend

Posted May 11, 2012 - 05:15 AM

#3

The marks on the bucket are normal. All the buckets spin, that one also gets hit by the decomp pin.
You're supposed to check clearance with cam caps properly torqued. Maybe I misunderstood, but if it changed after assembly, that's the number you should be working with. You'll need to re-shim that valve.
There is more than one timing mark on the flywheel. If you didn't remove both cams at the same time, it should still be timed right. Line the cam marks up with the top surface of the head and see what mark show in the window. You should be close. Maybe your timing chain is stretched, though. An 03 that hasn't had a timing chain done probably could use a new one. They're pretty cheap, but could be a pain to do. My flywheel was siezed to the crank and I had to cut it off. Fortunately, I was doing a total rebuild, anyway.


That's good news! Any clue as to why it won't turn over as it should? Could the cam chain have come off the lower sprocket?

  • Cooksend

Posted May 11, 2012 - 06:17 AM

#4

Would loctite be required on the bolts on the cam cover?

  • 07wr250

Posted May 11, 2012 - 06:24 AM

#5

That's good news! Any clue as to why it won't turn over as it should? Could the cam chain have come off the lower sprocket?


I may be over simplifying things, but it sounds to me like you were just fighting the compression of the engine. In your original post, you said it was tight every other rotation? Try removing the spark plug and manually turning the engine over a few times.

  • Just_a_trail_rider

Posted May 11, 2012 - 07:21 AM

#6

Yep... put zip ties around the cams and the chain. That will remind you where they go. But... read the book. Its easy to know how to set them back.

  • Cooksend

Posted May 11, 2012 - 08:27 AM

#7

I feel confident the cams went back in correctly. The tightness however is not from compression. All 6000the miles on the bike are mine. The cams both move freely so it is strange. Can a problem occur If the motor gets turned backwards while lining up the timing marks

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Frostbite

Posted May 12, 2012 - 01:48 AM

#8

I feel confident the cams went back in correctly. The tightness however is not from compression. All 6000the miles on the bike are mine. The cams both move freely so it is strange. Can a problem occur If the motor gets turned backwards while lining up the timing marks


You may simply be feeling the resistance from the valve springs. If you turn the engine over without the sparkplug installed then it will feel tight and loose as you turn it over, since some spots (like TDC) there is no resistance from the valve springs, and at other spots (when the valves are open) there is resistance.
Be careful when removing and installing the cams, always set the engine to TDC when removing and installing. Although the springs are fairly light, they have enough pressure to warp the cam if lobes are making contact when the cap bolts are not tightened. This is a remote possibility, but it could cause the engine to feel tight in spots. This happened to me, from loosening the caps without being at TDC. I checked the cam without the chain and lifters, so it could spin freely, and it had a tight spot. The cams are light and hollow. Hard to believe they can bend so easily, but they can.

The tighter valve after reassembly may be caused by the shim not properly seated under the bucket, or it may simply be a bit of reassembly oil taking up some clearance. That's why they suggest turning the engine over a few times before checking the clearances, so things get squished back into place. If the shim popped out of place under the bucket you'll have to remove and reposition it.

Edited by Frostbite, May 12, 2012 - 01:49 AM.


  • Frostbite

Posted May 12, 2012 - 01:59 AM

#9

Also, the dents in the bucket will chew up the cam lobe, this also happened to me. The decomp pin is beside the cam lobe, so it strikes the bucket in a different spot than the lobe. If the bucket didn't spin this would be fine, but it does, so the lobe does wipe across the dented area, and this grinds the lobe down. This happened to me once. I think my decomp pin was sticking. From this photo you can see that the pin was not turning - it's worn in 2 spots - where it first and last contacts the bucket. If the bucket is dented I'd replace it, and closely check the cam lobe for wear or damage.

Posted Image

  • Cooksend

Posted May 12, 2012 - 03:36 AM

#10

I am going to take things back apart tonight to try to figure out why the motor spins tight. It feels much more extreme than valve springs. The electric start almost doesnt have enough power to turn the motor over. Also kicking it is very dificult and you almost can't feel the compression storke. What are the chances that the cam chain could have come off the lower gear? I had a difficult time getting the cam chain over the exhaust cam sprocket once the intake cam was in place. I am hoping that if this is the case I did not do any damage turning the motor over! I will find out more tonight!

Thanks for the responses and help!

  • bg10459

Posted May 12, 2012 - 04:54 AM

#11

If the cam chain came completely off the lower sprocket it would be really loose and the cams wouldn't move when you spin the engine. If it was only half way on the sprocket the cam chain would probably be too tight to get the 2nd cam in. Normally there would be a bit of slack in the chain that gets taken up by the cam chain tensioner. If the chain came off the lower gear but made its way back on, it wouldn't be a problem as long as the crank and cams didn't move.

Now that I'm thinking more about it, though, I had a similar problem. I would feel tightness every few rotations. Turns out I had a damaged tooth on the primary gear on the clutch basket. A broken gear chip jammed between primary gears and broke a tooth off the crank gear, hence the need for a total rebuild. I replaced the broken crank gear, but didn't notice the slight dent on the clutch gear. Once I removed the clutch basket everything spun smoothly.

Also, did you make sure the cam alignment circlips were put back properly? I've done the job more than once, but the last time, I somehow forgot the clip on the exhaust cam. I saw it laying on the bench and knew immediately what it was. Fortunately, the engine was also still on the bench, but completely assembled. I pulled the valve cover and the exhaust cam had slid over and the gear was touching the side of the cylinder. Had I started it like that, I surely would have done some damage. Tragedy narrowly averted :banghead:

Edited by bg10459, May 12, 2012 - 05:09 AM.


  • Frostbite

Posted May 12, 2012 - 06:03 AM

#12

I am going to take things back apart tonight to try to figure out why the motor spins tight. It feels much more extreme than valve springs. The electric start almost doesnt have enough power to turn the motor over. Also kicking it is very dificult and you almost can't feel the compression storke. What are the chances that the cam chain could have come off the lower gear? I had a difficult time getting the cam chain over the exhaust cam sprocket once the intake cam was in place. I am hoping that if this is the case I did not do any damage turning the motor over! I will find out more tonight!

Thanks for the responses and help!


I thought it felt tight turning by hand. If it's tight kicking then there's definitely a problem. On the older WR's it was possible for the cam chain to hang down loose when disassembled and then 1 link hangs loose on the crank sprocket when you reassemble. If this is the case I believe the only real way to fix it is to open up the side cover so you can see the chain at the crank sprocket. I guess you could try pushing a wire coat hanger down into the bottom end to see if you could jig it back in place.

Edited by Frostbite, May 12, 2012 - 06:03 AM.


  • Cooksend

Posted May 12, 2012 - 04:47 PM

#13

:banghead:

Super thanks to those for there responses and help. Tonight I got home from work and took it back apart. Upon inspection all looked to be correct and in good shape. Now when I went back into my service manual my first thought was "Dumb Ass"... Adjusting valves but hey ya just may want to check the crank section as well. That is where they talk about the cam chain tensioner! Guess I didn't realize that you are suppose to reset the tensioner. I kind of assumed that it was preset and just took it out and screwed it back in! LOL...

Again thanks for your help! All three bikes I own are now ready for the riding season and I have a bit more knowledge than I did before! I have installed a Kouba Link on a CRF250X (Norman Kouba is a class act!), Rebuild the top end and completely redid my new to me 02 KX250 (Hare Scramble bike) and now adjusted the valves on my WR450!

A big thanks to TT and it's members for always pulling through when I need help!!!

Keep it real and Ride On!!!

  • Frostbite

Posted May 12, 2012 - 04:50 PM

#14

RIGHT ON, RIDE ON!




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.