timming mark is their spark every 360 or 720 degrees

2 replies to this topic
  • fridder

Posted October 03, 2005 - 08:55 AM


rebuilding 99 yz400f

when putting the cam chain on can you have it 360 degrees off on the lower timming chain sprocket?

does it supply spark every time the mark lines up or does it skip a revolution.

I know how the cam sprockets line up to the to the mounting surface of the valve cover and the cam loabs point out.

one revolution on the timming gear = one revolution on the piston so could I have it sparking when the piston is cumming up to exhaust?

the book does a great job of describbing most everything but haven't found anything to make me understand this problem

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • mkporn

Posted October 03, 2005 - 09:03 AM


no and yes. No to the three 360 and I think that it is a yes to the twice spark...

  • grayracer513

Posted October 03, 2005 - 09:15 AM


The ignition is crank triggered, and fires every rotation, creating a "wasted" spark during the overlap phase at the end of the exhaust stroke. It cannot be timed on the wrong TDC, since it is the camshafts that determine which is which.

Related Content


Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

05 yz450f not fast enough by RedeyeYZ

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  38 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.