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



70 replies to this topic
  • Indy_WR450

Posted January 13, 2004 - 04:08 AM

#41

I thought WR timing was 13 pins. Can anyone verify this? I think Chantz has an issue getting it back to WR timing. I think that is why it is not running well. :)

  • jchantzWR400F

Posted January 13, 2004 - 06:03 AM

#42

Here's the first picture without the hash marks on the cam chain and sprockets

http://www.imagestat...wr timing-pic 2

Here's the pic after hashing the chaing and the cam sprockets.

http://www.imagestat...fter hash marks

Here's the pic of my cam lobes at TDC.

http://www.imagestat...bes facing away


Sorry I couldn't figure out how to just get them to show up. So, just click on the link...

What do you guys think?

  • jchantzWR400F

Posted January 13, 2004 - 06:27 AM

#43

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.


First, I did mean the cam cover gasket.

Second, the TDC issue is where I've had some confusion. I can line up the "I" in the hole, then confirm that the 12:00 punch marks on both cam sprockets are facing up, and that the cam lobes are facing away from one another. The "E" and "I" timing marks on each cam sprocket are not exactly parallel with the head surface as it shows in my manual. I don't know how critical this is. If the 12:00 punch marks are up, and the lobes are facing away, then all I need to worry about is having 12 pins between the 12:00 marks for yz timing, and 13 for wr timing, right?

  • jchantzWR400F

Posted January 13, 2004 - 06:35 AM

#44

I thought WR timing was 13 pins. Can anyone verify this? I think Chantz has an issue getting it back to WR timing. I think that is why it is not running well. :)


I also thought it was supposed to have 13. Mine appears to have 14. That's one problem. I know I should assume that things got shifted around while moving the exhaust cam the first time around. But I did hash the chain and the exhaust cam and the intake cam so I would know where it originally was. When I couldn't get it to start (becuase of flooding), then I noticed the lack of compression (because of who knows what) I put it back to where the original marks lined up. Last night, I put the new plug in, and kicked it 3 times with out pulling the decomp lever. It fired up with the choke on, but sounded very poor. In fact, while it was running (for a matter of 1 minute or so) I pulled the hot start with the choke on and the rpm's seemed to build. When I shut the hot start off, and pushed the choke in, it died immediately. Not wanting to do damage, I didn't try again. I pulled the plug, and I was already starting to turn black. I was also wet when I took it out.

Not real sure whats going on here.

  • jwriott

Posted January 13, 2004 - 08:33 AM

#45

Those pictures don't look right. Something is off with your timing. From the picture I sent you, you should be 13 pins between the marks for WR timing, 12 for YZ timing.

You need to get a feeler gauge and check the valves as well after you get the cams back to the correct position.

Did you pull any of the buckets and shims out? I noticed when I did my valves last week that the shims need to be pushed down into the seat all the way. Otherwise, the bucket will ride too high contacting the cam.

  • jchantzWR400F

Posted January 13, 2004 - 08:41 AM

#46

Is it possible that stock timing on the 400's and 426's differ? That is to say stock on a 426 is 13 pins between the 12:00 marks, where stock on a 400 is 14? Just a thought. I'm starting to get the feeling that my timing is off at 14 pins between the 12:00 marks. If it were you, would you try advancing the exhaust cam (clockwise) 2 teeth to get to yz timing. Would you consider messing with the intake cam? Keep in mind that this was not touched. The chain never left the intake cam.

Also, I did not remove the buckets or the shims......

  • jchantzWR400F

Posted January 13, 2004 - 10:16 AM

#47

OK, so I've been searching TT to find more information on what my problem might be. I found this post that can confirm my timing marks on my cam sprockets not being even with the head. So, I feel a little better about that.

http://www.thumperta...true#Post519272

Still worried about the 14 pins, and the decomp issue.

  • jchantzWR400F

Posted January 13, 2004 - 10:26 AM

#48

I also found this post which may tell me why when after starting it last night and letting it run for a minute or so my plug was already turning black...

http://www.thumperta...true#Post515443

  • RichBaker

Posted January 13, 2004 - 03:13 PM

#49

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!!!!!!!


Did you actually pull the head off?? Or is it the cam cover that you're referring to? No reason to pull the head just to YZ-time the engine... :)

If it's the cam cover, a poor seal wouldn't cause loss of compression, just some oil seepage.

  • tctrailrider

Posted January 13, 2004 - 03:33 PM

#50

Looking at your pictures. If you are at TDC the intake cam is one tooth clockwise of where it should be. I have posted this earlier and will do it again.
Find TDC. Use a dowel in the plug hole, remove the flywheel case, use whatever method you prefer but find TDC. Reset the INTAKE CAM so the lobes are at 9-12-3. WR timing 13 pins, YZ 12 pins. The exhaust cam is set OFF the intake. Set the intake at TDC and the rest will follow.

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  • jchantzWR400F

Posted January 13, 2004 - 04:43 PM

#51

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!!!!!!!


Did you actually pull the head off?? Or is it the cam cover that you're referring to? No reason to pull the head just to YZ-time the engine... :)

If it's the cam cover, a poor seal wouldn't cause loss of compression, just some oil seepage.


I meant cam cover. Sorry for the confustion.

  • jchantzWR400F

Posted January 13, 2004 - 04:51 PM

#52

In the pictures, I'm not actually sure if the "I" mark in the hole on the case is lined up. I know It's close enough to have the punch marks in the up position, that is to say that the marks are at 9:00, 12:00, and 3:00 from left to right. The 9:00 and 3:00 may not be parallel to the head, but it should be close enough to make adjustments to the exhaust cam. I know that the intake is not off. During the procedure, the chain never left the intake cam. I hashed the intake cam at the 12:00 punch mark and hashed the chain. It never moved. From what everyone has said, I have no doubt that the exhaust cam is off a tooth for wr timing and 2 teeth for yz timing. Hopefully I can reset it tonight and it will cure the compression problems. I'll report back asap.

  • oldbones

Posted January 13, 2004 - 04:58 PM

#53

OK, this chain rides on 3 gears. One at the crank, and one for each cam. You know ONE of the three didn't move at all (intake cam), you are pretty sure you moved the second one one tooth (exhaust cam), but as for the crank gear, you don't know anything. The chain may have gone slack while you had it off the one cam and the tensioner loose, and when you pulled it tight again, it may have engaged a tooth off in either direction without you knowing it. That's why it is IMPERATIVE that you start at square one, TDC. Put something down the plug hole (screwdriver with end taped up) and VERIFY TDC. Then you can check the alignment of both cams. This may be your whole problem.

  • jchantzWR400F

Posted January 13, 2004 - 07:41 PM

#54

OK, this chain rides on 3 gears. One at the crank, and one for each cam. You know ONE of the three didn't move at all (intake cam), you are pretty sure you moved the second one one tooth (exhaust cam), but as for the crank gear, you don't know anything. The chain may have gone slack while you had it off the one cam and the tensioner loose, and when you pulled it tight again, it may have engaged a tooth off in either direction without you knowing it. That's why it is IMPERATIVE that you start at square one, TDC. Put something down the plug hole (screwdriver with end taped up) and VERIFY TDC. Then you can check the alignment of both cams. This may be your whole problem.


Exactly Oldbones. First, I want to thank everyone for the insight and help so far on TT. I also want to thank TT member DRZ400e (Jason) for helping me right the ship. :D to you Jason. Instead of trying to figure out what went wrong the first time (I'll chalk it up to "that's about my luck"), We finally decided to start from scratch. Pull the chain off of both cams, and align the cam sprockets (intake and exhaust) with what the timing plug "I" was showing TDC. We then reinstalled the chain on the intake cam, and then set the exhaust cam 12 pins off of that. We then reassembled everything and took it outside. Knocked on wood on the way out, crossed fingers, and threw holy water on the SOB. I kicked it twice, and it fired up. Sounded very clean running. Didn't get to take it for a test ride, I'm sure my neighbors were pissed just to hear it fire up at 10:00 at night. I will give a test ride asap to make sure my jetting is on. It was perfect before, and not sure how it will run without modifying. Hopefully, the yz timing mod will be worth the stress it put me through.

Now, I'm going to go tie one on. Thanks again for all the help. :)

  • oldbones

Posted January 13, 2004 - 07:59 PM

#55

Nice. Glad to hear it was an easy (read:cheap) fix. I am not sure on this motor, but my buddies kid did this with a brand new jap-spec fancy turbo motor for his car, and bent a bunch of valves. Same thing happened. Twin overhead cams, and they were messing around trying to port/polish the manifolds, so for some reason they had to pull the cams or cam chain. It slipped timing on the crank gear, and the rest is history.

  • jchantzWR400F

Posted January 14, 2004 - 05:50 AM

#56

I have no doubt that is what happened to me. First, It's very hard to keep the engine at TDC when you are jacking around with the cams. It will want to move around a little, and before you know it, your timing mark is not aligned with the mark on the case. Anyway, my theory is that when I pulled the chain off of the exhaust cam I didn't think about the possibility of it slipping off of the crank sprocket. As it show's in the picture I posted, I had 14 pins between 12:00 punch marks on the cam sprockets. I was able to get it to start this way. I didn't hear any odd engine noises except it sounded like it was ready to puke-but no wierd valve train noises. We tried to adjust the exhaust cam again to get to 13 pins. Tried to start it, and nothing. That's when we decided to start from scratch. I was a little worried at first, but then I figured if I took it to a shop, they would just look at the service manual-which I had. So, we took the whole damn thing apart, set the engine at TDC, installed the intake cam per the picture in the manual, and adjusted the exhaust cam 12 pins off of that. The rest is history.

My advice to anyone who tries this would be after you pull the exhaust cam out of the chain, make sure that the chain is kept as slack-free as possible. This will help ensure that the chain doesn't leave the crank. Becuase you can't see it down there, it's hard to tell if it stayed in the original position.

  • jwriott

Posted January 14, 2004 - 07:39 AM

#57

I agree not to let it go slack when performing this mod. I just lifted the whole assy up, pulled the cam down enough to clear the chain, rotated it and put it back. Basically, I had tensionon the cam chain the whole time.

I also just did my valves and had both cams out at once so the scenario that just happened to you could have happened to me as well. I was a little paranoid so I zip tied both cams to the chain and just lifted them up so I could get the shims and buckets out. I'll be sure to watch for this in the future.

Thanks everyone for helping me learn some new things as well. :) :D

  • jwriott

Posted January 16, 2004 - 07:46 PM

#58

So, does your bike run now? IF so, does it feel healthier with the YZ timing?

  • jchantzWR400F

Posted January 18, 2004 - 05:28 PM

#59

Well, it's time for the official ride report. I took it out for a few hours today. Mostly cold (25 F) and very sloppy. Not the best of conditions, but here's what I found.

The first thing I noticed was how much different it sounded after starting up. It's always started easy, and that hasn't changed. It sounded a little more crisp, and while reving, it sounded a little more eager. (If that makes sense) After hearing it idle and after giving a couple turns of the throttle, I could tell there was some real potential there.

Once riding, the most obvious change was that it really seemed to build rpm's quicker. Throttle sponse was improved. Another thing that I noticed, was how well it wanted to transition through the gears. That is to say, immediately after shifting, it was ready to pull. No waiting for the right (higer) rpm to wack the throttle wide open. That's a great feeling. It was no slouch to begin with, it's just improved now. I wish I would have done it sooner. It was well worth the stress. As for the added hit mid way through the rev range and on the top, It was hard to tell because of the slop. Hopefully, next time I ride, I will have better conditions. Thanks again to all those who offered words of wisdom. :)

  • Stefe9999

Posted January 18, 2004 - 06:57 PM

#60

Hey John,
I'm ready to do this mod now, most everything else on the bike is about perfect. How long would you say it takes?


-Steve
ps, we went and rode Pawnee National grasslands 2 weeks ago and had a pretty good time out there. Lots of variety.




 
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