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2001 300 ex top end rebuild

850 Views 6 Replies 3 Participants Last post by  SlammedRanger
I know, I know this has been posted over and over here probably and the one thread I found , that had a useful reply saying that the cam lobes are facing down on TDC is the compression stroke is helpful but im not sure what stroke the bike was taken apart on .. 300 ex that was torn apart already with a replated cylinder and piston and such .. anyways im getting the bike back together finally .. Since the cam was out I have no way of knowing if when it was taken apart it was on the compression stroke or not.. I have worked on tons of cars and all " consider me a shade tree" ... Is it possible to have it 180 degrees out ? does the spark plus fire every rotation no matter what .. ?? thanks for any reponses I get .. I have it properly timed and waiting on a manual chain adjuster now ... but I wanna know if the spark pattern can possibly be off or not ...

Thanks for any help guys !
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Any help would be appreciated it... Just wondering if im in a trial or error state atm .. or is there any way to figure out if im on the stroke that fires the spark plug or not before I put it back together ... really just wanna avoid doing it twice I can ... typing is easier " lol"
I've never had a Honda 300ex apart, but I assume it's similar to a Honda 300 4x4... The timing chain sprocket is marked with dots. They have to align. So it doesn't matter how the motor was taken apart, you have to ensure you get the timing marks lined up and the cam put in proper. I can't tell you off the top of my head, as I always refer to my service manual.

I suggest you download a manual!!!!!
Thanks for the response , however due to my own issues with communicating my problem I think you may have miss understood my issue .. I have the full manual for the bike in question ... and im just wondering what tells the ignition to spark on what rotation of the crank ... for instance does the cdi know when its on exhaust stroke or compression stroke to control the spark ... im just worried im putting it back together and its firing on the wrong stroke "if that's possible" is my problem since , or as long as I have it timed according to the T mark and the dash marks on the cam i shouldent have an issues no matter what crank rotation I am on?? I have no idea and cannot find the information I have used the search function a lot before picking you guys's minds ... I am very "nooby" to ATV repair work I understand how most of it works ... but never been this indepth with one .
The spark timing is taken from the pickup on the flywheel. As long as you lined up to the T and the cam lobes are facing downward and the marks on the cam sprocket line up your good. No other way to do anything wrong. As long as the woodruff key on the flywheel isnt sheered. Your timed correctly.

Awesome , meant to reply back earlier .. but I did some deep reading last night ... learned about a wasted spark ignitions system and how it works which is what these things are ... Something new to me ...

Thanks all for the help.
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