Just opened up my valve cover and found my timing chain broken. I was in fifth gear wide open and rear wheels locked, I pulled the clutch in a hurry !!!!

Tried to start the bike and everything was locked,so I put it in first gear and push it backward then retried to start . It's cranking but just like there is some valve bent..... no compression.... ahhhh


Anyway I will post pics soon!

Brokenbones,
Any warning? If you can, a few pictures of the damage.
Thanks,
Sid

Sooo, you say you were trying to crank it and no compression, of course there is not compression, your valves aren't opening and closing, nothing is spinning the crankshaft. Still though, depending on where the crankshaft was when that chain went, could be very possible valves have been bent.

I know some of the 700XX's in Baja have broke timing chains, hence the reason Alba came up with the heavy duty timing chain kit. To bad Alba doesn't sell those any more, one of the parts is discontinued. My plan is to replace my timing chain as part of regular maintenance. Hopefully that will be enough to avoid me ever breaking a timing chain.

Doug

Actually when you crank a ATV engine the crank is connecred from the starter gears assy so if the chain is broken, the piston compress and succion in and from the cylinder head that there is no valve cycling. If there is no compression some valve are bent or worst piston may be cracked. Imagine a syringue, try to push and pull while keeping the outlet/intlet close.

:-)

Also my chain is stuck in the lower case now. A good builder over here told me that on can-am they use a manual
Timing chain adjuster to avoid slapping. This way they report less breaking. ???? So as you stated hiperf cams springs need special maintenance for the timing chain when it's hight revved most of the time. BTW I had about 300 hours on this chain.

Thanks for your reply :-)

Depending on where the cam is in its rotation when the chain broke, the valves could be open, hence no compression. Chances are though, you will probably have some bent valves.

I plan on replacing my timing chain every 50 hours or so on my race 700XX, maybe 75 to 100 om my practice 700XX. I really wish there was still a heavy duty cam chain option for our quads. I will admit, I am paronoid about the timing chain on this thing.

Doug

[QUOTE=Brokenbones;115182 BTW I had about 300 hours on this chain.

i have over 300 hrs on my stk cam chain, i havent looked at the hr meter lately buts its way over 300 hrs and i have only a big3 motor. i hope it lastfor this summer and this winter i am going to do a build on my motor..

Doug, sorry for my English , I only seen the timing chain broken when I pull the valve cover, automaticly rockers no longer push on valves , hope it's more clear :-)

Ya if you have lost some compression then the valve is probably bent. Even if in the one and a million chance that the valve stayed open the pistion would definitly hit valve. If you want the the HD cam chain you can get it from alba. http://www.teamalbaracing.com/produc...cat=156&page=1

wow alba is proud of there hd cam chain kit heres one from honda oemhttp://www.partzilla.com/parts/searc...NER/parts.html

Have'nt called Alba yet but I think D.Bergstrom already tried and they no longer offer the kit because of the cam spocket availability.

Actually guys I think I just too much overrev it when I run it also I changed the brand of oil ( from klutz mx4 to maxima ) the lobes on the cam was blueish...

My build is a aggressive kit from Alba with a Barker pipe modded with a big core 2 3/8 I.D. and my own porting.

I will pull the engine as I have my stroker crank to install:-) I heard they are a bitch of a crank to pull out!?