Stupid YZ Timing Questions



12 replies to this topic
  • LarryCO

Posted November 21, 2001 - 05:15 AM

#1

I have 2 stupid questions involving the switching to YZ timing. Having not torn apart the cyllinder head yet, I'm only going by pictures/instructions listed in the technical section...

First of all, when advancing the exhaust cam gear by one tooth (from 0 to 1), I'm assuming one must take the timing chain off of the gear, advance the gear, and put the timing chain back on. Is this correct? I couldnt see how it wouldnt be, but then again, I dont want to screw up my machine...

Secondly, why must one take off both cam cap covers to simply advance the exhaust cam gear? Given that the cams obviously turn with the cam caps on, is this simply a case of not being able to remove the timing chain with the cam caps on? Or is there some other reason...

Wait a second...there's no such thing as a stupid question...just stupid people... :)

Thanks in advance.

Larry

  • MN_Kevin

Posted November 21, 2001 - 06:01 AM

#2

Larry,
When I rolled my exhaust cam, there was NOT enough slop in the chain to do it the easy way. I ziptied my intake cam to the chain, just so it could not come off. I also, using a permanent black marker, placed an alignment mark on BOTH the chain and intake & exhaust cam sprockets. I was really hesitant about doing it and had to make myself comfortable that I could get it back to normal, if any problems arose. I did have to remove BOTH cam covers, but I did try just removing the exhaust cam cover first, to try and roll it. ALSO, count the number of chain link pins between the marks, before and after. When you are all done, there should be one less pin between the two marks.

  • LarryCO

Posted November 21, 2001 - 06:09 AM

#3

NHKevin,
Thanks! Perhaps I'll give it a go this weekend.

It's funny...doing stuff to your bike for the first time, you're always a little wary (like tearing apart the carb). But having been through it once, you dont think twice about doing it again and again...

Any other special tips to note? I must admit, I still dont understand why you need to take off the intake cam cover to do this...just the exhaust cam cover, but I guess I'll find out myself.

Who knows...maybe I'll screw it up bad and come up with the extra special "Larry timing" (not to be confused with "Taffy timing")...where the little 'uns at the track on their 50's are lapping me! :)

  • finglan

Posted November 21, 2001 - 06:11 AM

#4

Larry,

When I did mine I just took off the one cam cap cover. I maked both cams and the chain in several places w/a sharpie marker so I would have some additional reference points. It was tight, but I pulled up the exhaust cam from the back, rotated the back of the cam towards the intake cam and then rotated the cam one tooth. I then slid the cam back in place pulling the back of the cam back towards the front of the bike. I had the marker points to confirm that the chain never moved on the intake cam and just one tooth on the exhaust cam. You should have 12 chain pins between the punch marks. Again the cam chain was tight even w/the tensioner disengaged. I helped a friend do his 98 WR and he had more play in the chain.

Be VERY careful not to drop the half moon bearing clip that is under the cam cap into the engine. Just go very slow taking off and putting on the cam cap. I found that you will have to rejet after the timing change. My bike became very rich down low and I could not compensate by just changing the jet needle clip posistion.

  • MN_Kevin

Posted November 21, 2001 - 06:19 AM

#5

finglan is ABSOLUTELY CORRECT. Watch that half moon spacer. As an added precaution, I stuffed a rag below the cam sprockets in case I dropped the clip. I did not this time, but did later. I fished it out with a parts grabber.

I had to remove both cam covers in order to tilt the sprockets down to give me the extra chain I needed to pull it over one tooth.

  • The_Missile

Posted November 22, 2001 - 06:35 AM

#6

Careful of the 1/2 moon thing....stuff rags into the timing chain holes. When reassembling use some grease to hold the 1/2 moon in place on the cover or it will be dfifficult to seat without it moving. Use the intake cam cover position as ref when reseating the cover. The edge of the cover does NOT align perfectly with the ege of the top end. It took me 15 minutes of pulling my hair out only for my dad to point out it was offset slightly on the intake and "just perhaps" it was the same on the exhaust!!

When I did mine, I just took of the intake cam cover and 'walked' a ripple of chain up and over the teeth. You have to pull the cam forward and over. Just use patience and dont force it. Use a zip tie on the intake cam chain/cog so you can pull and tug it without fear of it slipping off.

DONT overtighten the cam cover when retightening, use a torque wrench. DOC reported massive cam failure when a buddy overtightened the cover.

I too had to rejet (am still doing it).

Good luck

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  • Dougie

Posted November 22, 2001 - 07:23 AM

#7

You just can't stress enough about the 1/2 moon clips. The first time I went to YZ timing, I stuffed rags in the engine and then it still dropped. I just about lost my lunch. My stomach dropped to the floor. I couldn't move. I cramped up in panic and fear. I swear I damned near cried. Turns out though that is didn't actually fall all the way down. It was still in the top of the engine but it was hidden very well. I fished around for an hour with an extend magnet before I finally found it up top. WHEW!

When I went back to WR and then back to YZ timing later, I totally plugged up all holes and had an extend magnet in one had to grab it before it had a chance to go anywhere.

You will have to rejet. That means all that testing you did will have to be done again. But it will be worth it.

  • LarryCO

Posted November 26, 2001 - 05:50 AM

#8

Thanks guys for all of your input! I think a prerequisite before starting this mod is to get a parts grabber!

Dont have anything better to do now than monkey around on the bike...given all of the snow everywhere out here. SUCK!

  • WRFUN

Posted November 26, 2001 - 11:23 AM

#9

LarryCO,

Do you have the directions that Teamscream posted giving a step by step how to do the YZ timing mod? If not let me know and I will send you a copy.

pete

  • LarryCO

Posted November 26, 2001 - 11:43 AM

#10

Wrfun,
I do have directions (the ones from the technical section of the forum). However, if these are different from the ones you're referring to, any additional information would be helpful. You can send them to me at lawrence.b.haynes@att.net if you wouldnt mind...

Thanks!

  • Rocky

Posted November 26, 2001 - 03:33 PM

#11

Instructions on how to do YZ timing:
http://www.400thumpe...00/yztiming.htm

  • WRFUN

Posted November 27, 2001 - 05:53 PM

#12

LarryCo,

You got it.

Later,

Pete :)

  • Robert_Brazil

Posted November 28, 2001 - 09:08 AM

#13

Originally posted by LarryCO:
NHKevin,
Thanks! Perhaps I'll give it a go this weekend.

It's funny...doing stuff to your bike for the first time, you're always a little wary (like tearing apart the carb). But having been through it once, you dont think twice about doing it again and again...

Any other special tips to note? I must admit, I still dont understand why you need to take off the intake cam cover to do this...just the exhaust cam cover, but I guess I'll find out myself.

Who knows...maybe I'll screw it up bad and come up with the extra special "Larry timing" (not to be confused with "Taffy timing")...where the little 'uns at the track on their 50's are lapping me! :)


Can any one tell what is the difference between Larry and Taffy timing?




 
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