01 426 Hot Cams


7 replies to this topic
  • pbviking

Posted February 03, 2009 - 08:34 PM

#1

I am having trouble with a 01 yz 426. The bike ran fine until i took it apart to replace the cams (hot cams). I finished the cam replace and tried to start the bike....the bike would not start and every once in a while the bike would backfire So my questions is does the bike spark on the compression stroke and exhaust? maybe during the installation the magneto got turned 180 degrees the wrong way.

Any help would be appreciated

thanks,

  • rufusz

Posted February 04, 2009 - 12:10 AM

#2

You can't install the flywheel wrong because of the woodruff key. You should check the timing and see if it fires at TDC. There were several discussions here about not starting because of wrong timing.

  • Deathdeelr

Posted February 04, 2009 - 12:13 AM

#3

It's very possible you installed the cams 180 degrees out. That may be something you want to doublecheck.

  • grayracer513

Posted February 04, 2009 - 07:20 AM

#4

It's very possible you installed the cams 180 degrees out.

No it isn't. There is no difference between one TDC and another until the camshafts say so, so no matter which TDC one uses, the cams will be correctly placed as long as the timing marks all line up as they should.

This simply because there is an ignition event at every TDC, not every other one as is common in automotive engines.

Double check the timing, and remember that the cams must each be lined up with the cylinder head surface when the crank is at TDC. Be sure you have the correct valve clearance, also. Following that, you have to go back to what you would do with any other grumpy 426 that refuses to start; change the plug.

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  • Deathdeelr

Posted February 04, 2009 - 06:32 PM

#5

Gray, it's not possible to install the cams upside down? E facing I and so forth?

  • grayracer513

Posted February 04, 2009 - 08:20 PM

#6

Gray, it's not possible to install the cams upside down? E facing I and so forth?

Sure. Then if you rotate the engine 360 degrees, they're right all of a sudden. Cams rotate at half engine speed, so they're upside down at TDC every other revolution.

Besides, it would actually be very difficult to set them up that way because the lifters would keep pushing the lobes out of place unless everything was chained together. Try it if you like, you'll see what I mean.

  • Deathdeelr

Posted February 05, 2009 - 12:11 AM

#7

Sure. Then if you rotate the engine 360 degrees, they're right all of a sudden. Cams rotate at half engine speed, so they're upside down at TDC every other revolution.


You know, being a mechanic for most of my life you'd think I should have known that. Sorry. :)

  • pbviking

Posted February 21, 2009 - 06:02 PM

#8

UPDATE

I figure out the problem....Long story short It was the off switch cables

I put in both Hotcams exhaust and intake For those who have installed these cams... is the bike for difficult to start? before i installed the cams the bike would start in 1-2 kicks now i kick, kick, kick..............etc

i know when you update a car with a hot cam the car does not like to start and idle. Is this the same for a bike?


p.s.
i used the same plug and changed Spark is good too





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