Just switched to yz timing and..........

[tctrailrider]

Does anyone have a theory on being able to advance the exhaust cam 1 tooth, and not having to worry about whether or not the engine is at TDC when doing so? The instructions call for the engine to be at TDC. If all you're doing is advance the cam sprocket 1 tooth, does it matter?

It really doesn't matter if its exactly at TDC. The relationship of the crank and the two cams is what matters. The cam lobes can point in or out. Just make sure the lobes are not compressing the buckets, this would make reassemble very difficult. ?

[jchantzWR400F]

That's pretty much what I wanted to hear. So, can I assume then that all I really need to pay attention to is that (cam lobes out) on the punched timing marks on each cam sprocket (each on the 12:00 position) I should have 12 pins between them for yz timing, and 13 pins for WR timing?

Has anyone ever had more that 13 pins as stock WR timing?

[tctrailrider]

So, can I assume then that all I really need to pay attention to is that (cam lobes out) on the punched timing marks on each cam sprocket (each on the 12:00 position) I should have 12 pins between them for yz timing, and 13 pins for WR timing?

Correct. As a doudle check you should get it to TDC, lobes pointing out and verify that the intake punch marks are at 9-12 and 3. I have had two WR's and at TDC the intake cam marks line up very well. The exhaust cam marks are about 1/2 tooth clockwise with YZ timing and 1/2 tooth counter clockwise with WR timing.

[jchantzWR400F]

Thanks for the advice. I will double check the punch marks with the engine at TDC. Maybe I'm worrying too much about what the picture looks like in my manual. For example, in the picture, they show the marks lining up perfectly. My don't. But again, bike has always ran perfectly.

[darmino]

I think you may have moved the cam in the wrong direction or more than one tooth and the valves are opening before TDC

thats why you can kick it through without using the decompession lever( if so I just hope your pisdon didnt hit you valves )I have pictures that I took while doing mine so I could check before and after that everthing was perfect I can email you them if you post your address.And to everyone who has dropped the bearing clip in to the engine when removing the cam cap, you can avoid this by removing the cam with the cap still on, just lift up by the cam with your thumbs on the cap, you do have to wiggle it a bit

[jchantzWR400F]

I think you may have moved the cam in the wrong direction or more than one tooth and the valves are opening before TDC

thats why you can kick it through without using the decompession lever( if so I just hope your pisdon didnt hit you valves )I have pictures that I took while doing mine so I could check before and after that everthing was perfect I can email you them if you post your address.And to everyone who has dropped the bearing clip in to the engine when removing the cam cap, you can avoid this by removing the cam with the cap still on, just lift up by the cam with your thumbs on the cap, you do have to wiggle it a bit

Well, I did has a line through the cam chain, and the exhaust cam sprocket. I then pulled the cam up and forward towards me to get it out from the cam chain. I then turned the exhaust cam sprocket clockwise 1 tooth. I then reinserted the cam sprocket into the chain. Then reassembled.

My email address is chorman12@hotmail.com

I would love to see pictures.

Thanks

[Indy_WR450]

Try the Motoman 393 documents section of this forum he has pictures of the WR to YZ timing change. I hope that helps. ?

[jchantzWR400F]

Those were the instructions that I was using. It's a little hard to see the punch marks on the cam sprockets. At this point, I set the timing back to where it originally was. I'm going to pick up a new spark plug today and put it in. Then I'll try to start it up when I get home to see if I'm still having trouble with the compression. When I switched timing back, I did check the decomp system and it seemed to be working fine.

After thinking about it, the only other time that I had problems with being able to kick the bike over without pulling the decomp lever was when I changed handle bars last time. During the process I did realize that I had the gas turned on, and while trying to seat the throttle tube, I gave probably 30 turns of the throttle. Later when I went to start the bike, I was able to kick it over several times without having to use the decomp lever.

Maybe the non-use of the decomp is a symptom of a severly flooded bike. I don't know.

[jchantzWR400F]

So, can I assume then that all I really need to pay attention to is that (cam lobes out) on the punched timing marks on each cam sprocket (each on the 12:00 position) I should have 12 pins between them for yz timing, and 13 pins for WR timing?

Correct. As a doudle check you should get it to TDC, lobes pointing out and verify that the intake punch marks are at 9-12 and 3. I have had two WR's and at TDC the intake cam marks line up very well. The exhaust cam marks are about 1/2 tooth clockwise with YZ timing and 1/2 tooth counter clockwise with WR timing.

I'm at work now, so I can't confirm this, but I thought that when the lobes were facing away from one another that my punch marks were closer to 9:00 6:00 and 3:00. When the lobes are facing one another, the punch marks are at 9:00 12:00 and 3:00. ?

[tctrailrider]

I'm at work now, so I can't confirm this, but I thought that when the lobes were facing away from one another that my punch marks were closer to 9:00 6:00 and 3:00. When the lobes are facing one another, the punch marks are at 9:00 12:00 and 3:00.

I hope not. This would mean you spun a gear. You may want to consider removing the flywheel cover and finding the TDC mark on the flywheel. Position it close to the inspection hole, reinstall the cover, line it up and look at the intake cam marks. Lobes pointing out and marks at 3-12-9. Once this is correct go 12 pins on the exhaust. You will need to drain the oil to do this. The TDC mark is hard to find looking through the hole but is very clear with the cover off.

[jwriott]

Here's a pretty high resolution picture of my WR timing before I changed it to YZ timing.

Hope this helps.

WR Timing

[jchantzWR400F]

Great picture. That is about what mine looks like. Just to be certain, you basically what to get the exhaust cam sprocket out from the chain, and turn it clock wise 1 tooth. Then put the chain back on right?

[SXP]

Are you sure you don't have the decompression lever cable so tight so as to always have the exhaust valve open? Would explain why you can kick it through without holding the lever in and also why it wont start.

[jwriott]

That is what I did. I actually took white out and marked the exhaust cam and chain. Then I lifted the chain and rotated the cam one tooth clockwise from the end shown in the picture.

When I put it back down I knew I rotated it one tooth because of the white out. I thought I had a picture of this but I can't find it.

I do remember something in the manual saying to pull the compression release to make it easier to find TDC. I actually put a zip tie on the lever. When I went to measure the valves, I had a huge gap on the exhaust valve that is depressed by the compression release. I checked it several times before I realized I forgot to take the zip tie off. ?

If the cam looks like it is in right, I'd check your valve clearances before you do anything else.

[jchantzWR400F]

Are you sure you don't have the decompression lever cable so tight so as to always have the exhaust valve open? Would explain why you can kick it through without holding the lever in and also why it wont start.

With the cam cap off, I pulled and released the decomp lever several times to see how it was working. It seemd fine. That is to say, it did return to normal after pulling it. I don't have a feeler guage to check clearances now, I should have bought one today when I was out getting plugs, but, the bike was running and starting perfect 2 weeks ago. It was when I reassebled everything after changing the timing to yz, then flooded the piss out of it by going through the cold start procedure after the bike had been in a warm garage (it was only 25 F outside). The plug is fouled for sure. If have no doubt that's why it didn't start. It tried a few times (OK, about 75 kicks), but just wouldn't start.

[jchantzWR400F]

If the cam looks like it is in right, I'd check your valve clearances before you do anything else.

What I'm planning on doing (since the bike has been running perfect-it's always been a 1 or 2 kick bike) is putting a new plug in tonight to see if I can get it started. At this point I will know if I still have problems kicking it through without using the decomp. If everything seems back to normal, I will then attempt to set timing to yz spec (as I reset to WR timing yesterday). I will take pictures of what my stock timing is, and what I think it's supposed to look like with yz timing. Then you all can look at the pictures and tell me if I'm right.

[jchantzWR400F]

Well, I threw in a new plug. I was able to get it started. I still have the decomp problem. In fact, I pulled the choke, and kicked it about 3 times and it fired up. Didn't seem like it was running well at all.

So, I took it back apart to check things out. I took some pictures of my stock timing. By my count, I have 14 pins showing between the 12:00 punch marks on the cams. I Know I screwed with it on Saturday night, but I did make hash marks on the sprockets and chain before I even thought about moving the exhaust cam. Also, the chain never left the intake cam sprocket. After I had my problems, I put the exhaust cam back in line with the original mark that I made. So, it was put back the way I found it. And by my count, there are 14 pins (stock) between the marks.

I would love to post pics, but can't seem to access my imagestation account. If someone would host them for me on here, I would greatly appreciate it. Then maybe I can get a diagnosis from some of the more mechanically inclined here on TT. Get me going in the right direction.

My only theory on the decomp problem is that when I put the head gasket back on, I did not use any type of gasket goo, or adhesive what-so-ever. The stock gasket came off pretty well so I thought I could reuse it. There was some gasket residue on the head, but not much. Any chance that not having a perfect seal is causing my decomp woes?

HELP!!!!!!!

[DRz400e]

I will host them for you jackass. ? Give me a call.

[Rip Wheeler]

Maybe enough slack in the chain allowed it to jump on the crank gear ? Even though, it never came off the intake cam

[tctrailrider]

My only theory on the decomp problem is that when I put the head gasket back on, I did not use any type of gasket goo, or adhesive what-so-ever.

Are you referring to the head gasket or the cam cover gasket. If you removed the head ( everything above the piston top) the gasket could cause this. The gasket on the cam cover would not cause a compression issue.

I would suggest that you remove the comp. release for a test. One bolt and the unit will slide out. If you still have no compression either an exhaust valve is sticking open or the cams are off. The 14 pins is not right and somewhere along the line things got shuffled. Find TDC and verify that the intake punch marks are at 3-12-9 and then adjust the exhaust off the intake, 12 pins. To help in confirming where TDC is remove the plug and insert a long rod of some sort (wood or plastic) down the spark plug hole. Find the mark on the flywheel that puts the dowel at the top of the stroke, thats TDC. Good luck.

P.S. If you remove the decomp unit be careful when reinstalling the bolt, proper torque is only 2-3 lbs. and easy to strip, so I'm told.