timing marks

[corwine123]

just put my motor back together. when the pistons are at tdc the cam tdc indicate is at like 12:15 when it is supposed to be at twelve. does this mean im a tooth off on the cam sprocket or what?

 

[5twins]

Lots of teeth off, lol.

 

[corwine123]

lots of teeth? oh no. I was trying to go according to this
http://www.650motorcycles.com/CamTiming.html but seems I got it off a bit

 

[5twins]

I may have misread your post. Do you mean the index mark on the cam is off to the side just a little? Not quite pointing straight up? Or pointing sideways like at 9 or 3 o'clock? I assumed it was pointing sideways which would put you about 8 teeth off.

 

[corwine123]

it is pointing up. I have been reading some mroe of the manual though and think i may be pretty far off. From what i've read when one cylinder is tdc on the compression stroke the other should be at tdc on the exhaust stroke. on mine the exhause valve is not open at all at tdc. I reckon i'll be giving it another go tomorrow.

 

[5twins]

No, it sounds like you're OK. If you were even one tooth off, the index mark would be pointing to like 1 or 11 o'clock. The exhaust valve on the cylinder that's at TDC on the exhaust stroke won't be hanging fully open, just tight with no play and pretty much closed. That cylinder is actually right at the end of the exhaust stroke and just about to start on the intake stroke. The exhaust valve has just been open and let all the gases out, now it's closing and almost completely shut. The intake valve is just starting to open. That's why both valves are tight on that TDC stroke and clearances can't be set.

 

[corwine123]

these pictures are taken with the cam set where it should be at TDC. looks like i could be a tooth off.?

 

[corwine123]

little red mark is where it should be, longer red line is where it is. looks likes its off a tooth to me. off with the head again

 

[5twins]

Yes, from your pics, it does appear you're one tooth off.

 

[corwine123]

yep was a one tooth off. thanks for the help guys. And sorry for all the questions this is just my first time inside a motorsickle engine, other than putting an 88cc kit on my z50.