I'm in the middle of a top end rebuild right now and I want to make sure I get the cam chain in the right position.

In the manual it states having the rotor off so you can see the bottom cam chain sprocket. Mine is still in the bike and I don't have the tools to take it off.

Does the cam chain have a keeper or some sort of guide on it to keep the chain from skipping teeth on the bottom sprocket when you take the barrel and head off? Or am I going to have to build a rotor holder and a rotor puller just to make sure it's all still in tact?

All you need to do is set the piston at the correct TDC (your manual should tell you how)... After you set it to TDC install the camshaft so that the lobs are pointing down and install the cam sprocket and chain so that the timing marks on the sprocket line up with the mating surface on the head. The third mark on the sprocket should be up.

No need to take the rotor off. After you are done, turn the motor over by hand a few times after you get everything lined up to make sure there's no interference for when you go to start it.

Thanks! That saves me hours of needless angst. So I guess all that indication mark on the lower cam sprocket is for is to tell if the piston is at TDC then.

I bolted it all back up to together and spun the engine around a few times and all seems to be well.

43F model. How can I find TDC with the rotor still installed and the top end off? I can't find anywhere in my Clymer manual how to do it. I can align the timing mark on the rotor but how can I check if it's TDC? Thanks for any and all help.

It's explained very well here in this quote. make sure the top dead center mark on the rotor is at the top, pointing towards the cam above and follow what's in the quote above.

just rebuilt my top end on my 89 ,fresh bore, new piston , rings , cam chain , valve seals and lapped the valves and head ..

there is a thread here on this forum ( it's a sticky) with a link to down load a free factory manual it's a zipped file in pdf format , (you'll need winzip or winrar to open it and the adobe reader to read the pdf version once unzipped , all free to download ) it's for a 90 xt600E so depending what year you have it maybe certin slight differences .. like 89's and below have seperate oil tanks mounted under the seat , behind the side number plate, while 90 and up the oil tank is in the frame , rear disc brakes 90 and up , also electric start 90 and above and some other small things. But for the major work,, its all the same .

Randy

Thanks, I was having a duh moment. The piston is always at top dead center with the timing marks but the camshaft and valves are with every other revolution. I didn't just fail Engine 101, I never even took the class!