WR/YZ cam timing (take 2) 14 chain pins with pics


16 replies to this topic
  • un chained

Posted May 15, 2012 - 06:42 AM

#1

[color=#222222]After riding the bike with the exhaust cam rotated clockwise (12 pins), I couldn’t tear it apart fast enough because it had no low end or mid and the increased RPM's were pretty much useless. After tons of googling and research, I came across a couple pics that clearly show 14 chain pins between the cam dots and also 1 article that explains that the cam dots should not be used but to time them by viewing the cam lobes in relationship to each other and in a parallel line across the head. I also noticed that the Hotcams intake cam/sprocket is adjustable so that made me wonder if the intake cam timing is really what tames down a WR or makes a YZ a "fire breathing monster". [/color]


[color=#222222][color=#222222] [/color][/color]
[color=#222222]So, I put the exhaust cam back to the location it was when I first opened it up and then rotated the intake cam 1 tooth clockwise. I’m at 14 pins and the lobes are parallel as shown in the m.bobbit.home.comcast.net (auto decompression upgrade) illustration and the sprockets appear to be exactly as shown in the YZ pic with the red screwdriver sticking up (random from the internet (allthigsmoto.com). [/color]

[color=#222222]Bike starts, idles and sounds great. Def much improved low end and mid-range but not as peaky as the 12 pin exhaust cam only move. Not so sure if it’s stronger than stock WR timing and now I’m really wondering if the WR and YZ cams are indeed different therefore no combination of timing will truly achieve YZ performance with stock WR cams. I have a stock 02 YZ muffler on the way and will test again with the stock uncorked WR muffler before I move any further. Please check out the pics and chime in with comments or thoughts. thanks,,,[/color]

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[font="Times New Roman"][size="3"][color="#000000"]Posted Image[/color][/size][/font]Posted Image

Edited by un chained, May 15, 2012 - 06:48 AM.


  • MANIAC998

Posted May 15, 2012 - 06:29 PM

#2

We need to know what model/year bike you've got.
Maniac

  • zibbit u2

Posted May 15, 2012 - 08:05 PM

#3

I'll guess it's a WR400, due to steel frame and 3 bolt holes for the upper rear engine mount.... but that's only a guess.

  • MANIAC998

Posted May 16, 2012 - 04:03 AM

#4

Hot start on the carb too. So I'd say that's a pretty good guess!!!
Maniac

  • un chained

Posted May 16, 2012 - 07:22 AM

#5

Sorry, 2002 WR 426
This is my 2nd recent post about this topic so I assumed the specifics were already known.

Heres my first post about it a few days ago...

http://www.thumperta...g-my-head-help/



[color=#222222]The last pic there with the red screwdriver was a random YZ 426 pic I found on the internet. The top 2 pics are from my bike recently taken. I was just showing other examples of the same timing that does not jive with the rule of rotating the exhaust cam 1 tooth clockwise on a WR for YZ timing threads I've been reading everywhere. The bike basicaly ran like a turd at 12 pins and the exhaust cam 1 tooth clockwise so I did more research and came across that "450 auto decompression upgrade" article that clearly shows 14 pins and the intake cam clockwise 1 tooth and the exhaust cam where mine was when I first broke into the engine. It made me question if the intake cam should be moved and not the exhaust to make a WR run like a YZ. I've never ridden a YZ 426 but I got my ass kicked and headlight busted by a little kid on 1 when I was riding my 01 Husqvarna TE 610 so I know they rip. I’m really thinking the 2002 YZ and WR cams are not the same and simply rotating the WR cams does not achieve true YZ cam timing based on all of the combinations I've tried on my WR.[/color]

Edited by un chained, May 16, 2012 - 08:33 AM.


  • un chained

Posted May 17, 2012 - 05:00 AM

#6

[color=#222222]I've decided that the WR's flywheel weight, wider ratio gearing and 20 or so extra pounds is 2 much for the YZ cam timing mod to overcome. The original 1 tooth (exhaust) clockwise method may very well be correct but the flywheel weight, bike weight and gearing is why it just didn’t hit as hard as a YZ? I put a lot of time into these post including pics, spell check, grammar not to mention a ton of prior/old post searching to have little to no interest from other members so I'll simply put it back to stock WR timing and go riding...[/color]

  • un chained

Posted May 20, 2012 - 03:12 PM

#7

I guess I can't help myself.

My used eBay YZ muffler (stock) with a drd spark arrestor cap showed up so before I pulled the valve cover back off to put the cams back to WR stock, I threw the pipe on and took it for a quick spin. Needless to say, I am pretty sure that I'm onto the YZ cam timing because it is now explosive and crazy fast. Incredible throttle response and there may be slightly less low end now but you would never know because the mid comes on so fast and strong that its hard to determine if there's less grunt now. Only rode about 10 min without being geared up but hands down, 14 pins and the orientation like the above pics is what I was seeking all along. The stock uncorked WR muffler was the problem and explains why nothing I did before made much of a difference until now...

Edited by un chained, May 21, 2012 - 02:56 AM.


  • un chained

Posted May 26, 2012 - 09:13 PM

#8

After about 40 miles today, it has been confirmed. 14 pins, intake cam rotated clockwise, exhaust cam WR stock and it rips. I'm now convinced that all the other stuff about rotating the exhaust cam is garbage. Leave the exhaust cam alone, move the intake cam clockwise 1 tooth and hang on...

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  • NoRubber

Posted September 11, 2012 - 07:33 AM

#9

This sounds good. But why is everyone else saying to rotate exhaust cam?

Anyone to back this method up?

Newbie question, when you are saying rotate clockwise, you mean looking at the engine from left hand side?

  • exracer2

Posted September 11, 2012 - 12:51 PM

#10

You might be on to something here. I purchase a hot cam off ebay for my wr 400 and tried the timing as per the instructions, 13 pins, then moved it to 12 pins. The bike wouldn't even start. So i am back to 13 pins. My wr400 does not run like my yz426 so i guess i need to take both of my valve covers off and check them both to see what is the differents. exracer2.

  • e36graduate

Posted September 15, 2012 - 06:23 AM

#11

I've had my wr426 apart quite a bit and I've got a 2001 WR426 that is street legal so I get to open it up quite a bit on straight, flat roads.

I have the original WR cams set to 12 pins (exhaust cam +1). I have a YZ exhaust insert. Unfortunately my stator and flywheel are off (stator being repaired) and I have a YZ426 stator/flywheel installed.

I am 210 lbs and 6'. I sit where it is comfortable, kind of close to tank. This bike will wheelie in 3rd gear without any pulling of handlebars, you basically are going along and then hit the gas and she WILL come up to a nice angle for a long wheelie.. 4th gear will require a yank of the bars to wheelie.

My valve clearances are all good, intakes are on the lower side of spec but "in-spec". I like the bike so much I am selling my kx500 and getting a wr426 as a back up.

  • Chaddlez

Posted January 08, 2013 - 02:46 PM

#12

Can confirm the 14 tooth setup works a treat I thought I was on a yzf I havent done grey wire mod yet or the throttle stop but have a yz exhaust thanks UNCHAINED

  • Birdy426

Posted January 11, 2013 - 04:56 PM

#13

You might be on to something here. I purchase a hot cam off ebay for my wr 400 and tried the timing as per the instructions, 13 pins, then moved it to 12 pins. The bike wouldn't even start. So i am back to 13 pins. My wr400 does not run like my yz426 so i guess i need to take both of my valve covers off and check them both to see what is the differents. exracer2.


Are you talking intake or exhaust Hot Cam? With Hot Cams, assuming you have the autodecompression exhaust cam, you don't count pins, you set to the timing marks. With that said, the hot cams exhaust cam doesn't add much beyond a stock cam at YZ spec, but the intake sure does wake things up...

  • exracer2

Posted January 11, 2013 - 07:35 PM

#14

Are you talking intake or exhaust Hot Cam? With Hot Cams, assuming you have the autodecompression exhaust cam, you don't count pins, you set to the timing marks. With that said, the hot cams exhaust cam doesn't add much beyond a stock cam at YZ spec, but the intake sure does wake things up...

. I have auto decompression exhaust cams only. So if I install intakes it will wake things up? Guess that my next move then! Exracer2

  • highmarker

Posted January 11, 2013 - 07:54 PM

#15

Advance the intake too far and the valve can get close to the piston, 1 tooth is quite a few crank degrees

  • Birdy426

Posted January 11, 2013 - 10:00 PM

#16

. I have auto decompression exhaust cams only. So if I install intakes it will wake things up? Guess that my next move then! Exracer2


Truth be told, the stock YZ pipe made a bigger difference than the hot cams intake on my WR (that was already YZ timed...) although your mileage may vary...I didn't swap the WR pipe back on to try just the hot cams with the WR pipe...

  • exracer2

Posted January 13, 2013 - 07:46 AM

#17

That was my next move. Just bought a new / used pipe to put on. Will try it out today. Gonna have to rejet

it too.




 
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