finding TDC with a 336 cam
I just want to start out by saying I have been a lurker for about 8 months now and have found really all the info I needed with out having to ask. But now ran into a possible issue. I have a R75/6 frame with a R90/6 engine and some previous owner installed a 336 cam in the late 90's. The bike sat for 2 years cause the guy I bought it from wanted to cafe it out and cut too many wires and couldnt figure out how to make it right again.
I am trying to check valve clearance but I am unsure if I can still use the marking (OT) on the fly wheel to find TDC. From my reading the 336 cam prolongs the compression stroke so will that also change how to find TDC. Also while I am thinking of it, is the timing affected by the cam also. If so what do you all recommend I set the timing to.
Thanks ahead of time
It's just this simple....
1/2,...one half of a turn....past Top Dead Center,....TDC..., with both valves closed,....is the power stroke....
That's 90 degrees of flywheel turn.
So,....at least half of that 90 degrees, ...probably slightly more,.... both valves will be closed.
Any point in that first 45+ degrees of flywheel turn,....that would be 1/4...one quarter of a turn.... after Top Dead Center, (TDC), the valve train will be slack.
There lies your opportunity to set your valves with the cam lobes out of play, and the valve train totally slack.
Watch the rocker arms. When the intake valve closes, you are on your way to TDC on the compression stroke. The power stroke is next.
Actually,..any point in motor rotation after the intake valve closes and before the exhaust valve starts to open is fine for setting valve clearance.