Thread: Cam Timing

out of my realm of knowledge, but i know we have some members on here that can probably answer that.

set the crank to top dead center and then find the manual for how the cams are supposed to line up while the engine is at tdc
if they were fine when you took it off they should still be fine

you should always check them. but, they should not move as long as the cam stays in place as well as the rockers and valves

to align them i always turned the crank to tdc (during the firing stroke) and lined the marks up on the gears(all valves closed)
however this may be different for your bike

ALWAYS turn the engine over by hand with the spark plug out first. in case you do not get them lined up and the valve and piston collide this will minimize damage if any is sustained at all.

I thought compression?

It doesnt matter, as long as the mark is line up it is fine. Unless there is something majorly wrong with the rotor

Originally Posted by off_road_4_me

I thought compression?

compression, ignition, and combustion are all on the the tdc revolution

No, the lobes should be pointing out wards, the dot should line up with the cam tunnel, you will see what i mean

it only matters if you are checking your valves, in which case you can check to see which stroke you are on my feeling to see if the rockers are under pressure. on the Raptors, there are two different marks for timing and checking valves which you might check for. some quads ive worked on did not have a timing mark on the bottom end, but i was able to time it perfectly by looking in the spark plug hole and spinning the flywheel until the piston was perfectly balanced up top, then centering the cam mark. you would feel a very tiny bump when you hit TDC and most of the time you dont feel it.

if the valves were okay before, you are fine, but it wouldnt hurt to check them while your at it. if you have both timing marks lined up, or if you have the piston at TDC and the cam mark centered, simply make sure the cam chain is on at the bottom, because if its not usually the only way i can get it back on is to take the cylinder back off, make sure the sliders are installed properly, and stick the chain back on perfectly, then tighten the chain. if you broke the chain, just put the masterlink back on after perfectly centering the chain on the cam sprocket. some cam chains do not have masterlinks, in this case after you achieve TDC on the bottom end, without spinning the bottom end, get the tightest link on the cam tooth and spin the cam to get the chain on, like you would putting a bicycle chain on, make sure the adjustment is all the way out so you dont break or stretch the chain, you need to be very careful because this is easy to do. once you have it back together spin the enigne over a few times and make sure the marks still line up perfectly, this usually takes a few tries.

If you get the chain tensioned correctly, and after spinning the engine over the marks keep getting way off, or it wont start, or if you can hold the flywheel while spinning the cam over, the chain slipped off the crank, so most of the time this means taking the cylinder off and fishing it back on there.

Good Luck!