cam shaft alignment.

[400exStar]

I have a 416ex with a hotcam. I was out riding the other day and it made a funny noise running at low RPM and it quit would not start and will not start. I have spark, compression, gas and everything. I took the valve cover off to look at the cam shaft alignment and it appeared to me that my chain had skipped a few teeth. I set it up at TDC and aligned my sprocket and tightened it all back down. When I put it back together it sounded crazy. So i rotated the cam 180 degrees and tightend her all up again and still the same sound and no start. I know the timing is screwed I can just hear it. It isnt right.

My question is; is the alightment on a hotcam the same as the alignment on a stock cam? I have it at TDC with all three cam sprocket indicators lined up. But I know it isnt right. My starter will hardly even turn the engine and I have a full charge on the battery. It is hanging up on the compression stroke because the timing is off I believe. any help will be greatly appreciated.

[Colby@C&DRacing]

the hotcam times the same as the stock one. You may want to check your cam chain adjuster, and make sure your valves are adjusted correct.

[400exStar]

it is not possible to install the cam 180 out correct? as long as the engine is at tdc and the cam sprocket is aligned I should be ON whether the cam lobes are up or down correct?

[Colby@C&DRacing]

the cam lobes need to point down with what you already described..

[JOEX]

If the chain slipped a few teeth could the valves be bent?

[400exStar]

Please pardon my ignorance, this is my first engine crack so.

Assuming my timing is all screwed up and I am starting from scratch. with my crank at TDC, the bottom part of the engine has no idea which stroke it is on correct? so, if that is true, does it really matter if the cam lobes are up or down, if i rotate the crank 360 then the lobe positions are opposite than what they were on the last roatation. So does it really matter when you are starting from scratch which position the lobes are in as long as the notches line up?

[BSTURDIVANT]

Originally posted by 400exStar
Please pardon my ignorance, this is my first engine crack so.

Assuming my timing is all screwed up and I am starting from scratch. with my crank at TDC, the bottom part of the engine has no idea which stroke it is on correct? so, if that is true, does it really matter if the cam lobes are up or down, if i rotate the crank 360 then the lobe positions are opposite than what they were on the last roatation. So does it really matter when you are starting from scratch which position the lobes are in as long as the notches line up?

True, but you have to have the cam lobes down on a 400EX to put the rocker cap on anyway!

[400exStar]

yes that is true. What I was getting at was that I installed it with the lobes up, then rotated the crank one rev. to put the lobes down. I just wanted to make sure this was ok. Something is was messed up though. It sounds crazy. Valves appear to be adjusted correctly. I cant fig it out. I followed the clymer manual to the T. I guess I'll start again tomorrow.

[400exStar]

Alright I went back and removed the cam and everything else and started from ZERO.I rotated the crank to TDC and installed the Cam and sprocket as recommended in the Clymer Manual (which seems obvious given the markings on the sprocket). I put the head cover back on and tightened the main bolts down. I then attempted to rotate the crank with a ratchet and 17mm socket and all of a sudden It stops dead just before TDC as if the valves and the piston are hitting (thank God I did this by hand). Now I dont know WTF is going on. Everything appears to be in place. I am pretty sure that even if you install a camshaft 180 out and completely upside down, the engine will still roll freely with no interference between the valves and the piston. I dont get it.

[QIKLTR]

sounds like you dropped a valve to me

[400exStar]

Just to update you guys. The problem I am having is that my motor sheared the pin on the flywheel. That is why I could not align tdc. Now that I fixed that problem, timing is spot on and it runs great. I am still having a Valve job done just because I have the head off but I thought I would let you all know in case you ever have a prob like this. I would never have know except for the fact that I pulled off the stator cover b/c I thought maybe there was soemthing wront with my spark. So if you have a prob with timing and no matter what you do the timing come out wrong, check the flywheel pin and make sure it isnt sheared. live and learn.

[bwamos]

Good find. Cheap fix to boot. :)

[sc400ex_rider]

by flywheel pin do you mean the keyway? was it stock or advance one?