426 exhaust cam


9 replies to this topic
  • mac777

Posted December 21, 2008 - 12:41 PM

#1

hi, i have just put a 450 exhaust cam in my 426f 2002 ,the bike runs ok .do you time the cams the same as with two 426 cams in place ie, the dots on the sprockets.any help much needed.
merry xmas and a happy new year from sunny wet and windy scotland:banghead:

  • grayracer513

Posted December 21, 2008 - 02:21 PM

#2

hi, i have just put a 450 exhaust cam in my 426f 2002 ,the bike runs ok .do you time the cams the same as with two 426 cams in place ie, the dots on the sprockets.any help much needed.
merry xmas and a happy new year from sunny wet and windy scotland:banghead:

No, absolutely not. Because the 450 cam was made for a different head, the timing marks on the cam can't be used as the stock ones are. What must be done is to time the intake correctly by the book, then time the 450 exhaust cam off of that by counting 14 pins between the two marks at 12:00 o'clock on the cams.

If the cam was an aftermarket, "450 type" cam that was actually made for the 426, that's different, and the marks should be used as the stock ones are.

Read:

http://www.thumperta...078#post3706078

and,

http://www.thumperta...040#post5378040

  • mac777

Posted December 22, 2008 - 11:47 AM

#3

thanks top guy,hope i have not screwed the motor i will retime it at the weekend.read the links you sent ,a great help.thanks again and all the best for 2009

  • 642MX

Posted December 22, 2008 - 05:11 PM

#4

thanks top guy,hope i have not screwed the motor i will retime it at the weekend.read the links you sent ,a great help.thanks again and all the best for 2009


I seriously doubt your piston made any contact with the valves. I've seen guys do this before and they didn't damage anything.

The easiest way to time the 426 with the 450 cam is to: Be sure your on TDC, install the intake cam and then install the exhaust cam with the timing marks lined up.... and then rotate the (450) exhaust cam counter-clockwise one tooth. It will look out of time, but its how you do it. Now install the tensioner and button it back up.

  • mac777

Posted December 23, 2008 - 08:07 AM

#5

thanks .now is it one pin forward or will counting 14 pins asGRAYRACER said, dont want a fight here.only a joke lads.the bike did feel flat when i ran it ,so the timing being out makes a lot off sense.thanks again

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  • 642MX

Posted December 23, 2008 - 08:46 AM

#6

thanks .now is it one pin forward or will counting 14 pins asGRAYRACER said, dont want a fight here.only a joke lads.the bike did feel flat when i ran it ,so the timing being out makes a lot off sense.thanks again


Me and Gray don't fight...we might argue, but its all in good fun. After you rotate the exhaust cam, you'll have the 14 pins between the top punch marks, like Gray stated. :busted:

  • grayracer513

Posted December 23, 2008 - 12:09 PM

#7

Me and Gray don't fight...we might argue, but its all in good fun. After you rotate the exhaust cam, you'll have the 14 pins between the top punch marks, like Gray stated. :busted:

It's a discussion forum, not a Q&A forum. :moon:

What you have is two ways to arrive in the same place. Timing the 450 cam is a little more of a nuisance than the stockers, because the best way to get it done quickly is to time the exhaust first, so the front side of the chain can be held tight while the intake is timed. You can time the exhaust, drop the chain in the right place by counting pins between cams, and drop the intake in. Then if the marks line up right, you're done. But, if you use 642's approach, you can do the same thing with the 450 cams, if you get a little lucky.

Line the marks up on the exhaust cam, roll it one tooth forward, then set the intake at 14 pins apart from the intake and set it in place. Back all three shafts up a few degrees, then carefully rotate the crank forward to TDC and check. The intake should line up as it does in a stock bike, and there should be 14 pins between the intake and exhaust top marks.

  • mac777

Posted December 23, 2008 - 12:22 PM

#8

thanks lads i feel better now.merry xmas and a very happy new year

  • mac777

Posted December 26, 2008 - 05:57 AM

#9

thanks to GRAYRACER and 642mx, retimed the engine as the guys stated, what a difference, now we are back to a snorting 4stroke.starting is so eazy even when hot ,any other tips will be chased up.thanks for your advice and hope you have a great 2009.

  • 642MX

Posted December 26, 2008 - 06:50 AM

#10

Your welcome mac777. :busted:





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