Jump to content
Sign in to follow this  

Yamaha Possible Damage to Piston

Recommended Posts

:thumbsup::banghead::banghead:Hey everyone. I recently screwed my cylinder head and somehow the intake cam jumped the timeing chain and bent all my intake valves. Upon inspection of the piston head there was only a couple of scratches on the piston head. No gouges or deep scars. I am trying to find out when this happend if there could be any damage to the internal piston rod and king pin. The quad turns over fine after the head was taken off and there is no pinging that I can hear. I need to know if someone can give me some advice about what I should do before I reinstall the head I just spent close to $800 on rebuilding with aftermarket valves springs, etc. and hotcams stage 1 cams. Also had it ported and polished by PPE performance engines. Please let me know if anyone has anything to check on or replace before I screw up anything else on my quad. Thanks:foul::ride::foul:

Share this post


Link to post
Share on other sites

If it were mine, I would replace the piston and rings since the engine is already apart. Pistons and rings wear out and should be replaced at regular intervals anyway. Have you determined why the cam jumped timing? This usually doesn't happen unless there is a problem with the cam chain or the tensioner. Make sure you get the root cause of the failure fixed. Take it from someone who has learned the hard way that it is way more expensive to fix something two or three times trying to go cheap than it is to fix properly once.

Share this post


Link to post
Share on other sites

Yubamike, yes I found out what the cause of it was. Like a retard I didn't put enough as in none at all assembly lube back on the intake cam. It fell in the garage floor and hit some sand from the tires so I cleaned it off and put it back together after done shimming the valves. It started fine got on it to break in the shimms and all of a sudden it stoped running. As soon as it happened I knew what was wrong. Trust me man I feel more stupid than stupid could feel, lol. I have replaced the chain and tensioner just in case and just had a mechanic check out the piston and crank yesterday and believe it or not no damage other than a little scratch where the intake valves hit. The lobes on the intake cam were pointing the same direction as the exhaust. All fixed now though...... I would love to change it out but the money is a major factor at this point. I have none. But plan on doing it soon. I am putting it back together on Thursday and will let everyone know how it works out. Thanks for the info. Its appreciated

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×