The sprocket will only bolt to the cam one way, you cant get it backwards. When the lobes are facing away from eachother the timimg marks will line up. I always tac weld my sprockets to my cams, it makes it easier for reinstallation.

NOTE* I always used the line were the two halves of the cam cradle meet to line up my cams, not the black arrows. My motor always seems to run better that way.



bigger.

 

I don't have my cams gears to check but don't the cam gears have 2 timing marks,180* from each other? Kinda like -O- , where - = timing marks on the cam gear and O = cam gear

 

Thats correct, but if you remember the sprocket has a dawl(sp) that fits into the cam so that the sprocket is always in the right position in relation to the cam lobes. I really wish Rotax wouldnt have put the second " - " on each cam sprocket, thier would be no confusion if it was just " O- )( -O " instead of " -O- )( -O- ya know.


bigger.

 

I couldn't agree more!

-O- )( -O- take this and rotate each cam 180*, the timing marks will still line up (due to the dual timing marks on the cam gears), just the lobes will b e facing a different direction. And as long as we started with the crank at TDC, by rotating the cams 180* which will rotate the crank 360* the crank will be at TDC.

So this would mean that it is possible to disassemble the engine with the crank at TDC, cam gear timing marks lined up but by not looking at the cam lobes you would not know the cams orientation.

 

Well it really wouldn't matter. The cams determine what "stroke" the motor is on. so if the cams were say pulled off with the motor at TDC between strokes 2 and 3 it would not matter. As soon as you put the cams back on,and set them back to " ZERO" the cycle will start over with stroke #1. Thats probably the reason for the engine firing every TDC. So you wouldnt have to worry about Ignition timing,and cam timing both.

Also remember the spockets are much larger around then the cams themselves, so rotating them 180 degree's would rotate the cams even more than 180. The cam sprocket are geared with the crank, but the cams are "geared" with the speed of the piston.




bigger.