Full rotation on M900 Cams?

[nomadwarmachine]

Let me see if I can phrase this clearly.  What is the full cycle of rotation on the cams in a 2000 M900Sie motor?  In other words, is a full cycle one revolution (360 degrees) or two revolutions (720 degrees), or heaven forfend, something in between?

Preparing to do the valves with the belts off this weekend and realized that I never knew the answer to this question.  Just want to be sure that, when I put the belts back on, I do not have the cams out-of-phase with the crank.

[DaFoose]

Ican't answer this question, but why not just leave the belts on while you do the valves, then change them after the valves are doen (or vice versa)? I would guess it would be 1 rotation (if I was watching a game show on tv and had multiple choice answers).

[nomadwarmachine]

I've normally done the valves in the past with the belts on, but I've wanted to do them w/out belts so that I can properly check for binding.  Anyone?  Bueller?

[greenmonster]

Just want to be sure that, when I put the belts back on, I do not have the cams out-of-phase with the crank.

When all 3 camwheels align w their respective mark/dot,
you`re in phase. Yes, it`s as simple as that.

I've wanted to do them w/out belts so that I can properly check for binding.

Wise I think, as you say, much easier to check binding.


IIRC a full cycle is 720.

[nomadwarmachine]

It makes sense that a full cycle would be 720 degrees, since valves open and close TWICE on each combustion cycle.  I know that that the marks need to line up, but it is theoretically possible for the crank to be at 0/720 and the cam to be at 360, or vice versa.  I think that would be bad.

In any event, I fully intend to rotate the motor repeatedly by hand to make sure everything is matching up before I hit the starter button.

[caperix]

The cams turn at half crank speed so the crank will rotate twise, 720 degrees for 1 cam rotion.  As long as the dots line up you will not be out of time.

[nomadwarmachine]

Ah, but if the belts are off, the cam can line up out-of phase!  Thanks, I think I have what I need.

[Speeddog]

When all 3 camwheels align w their respective mark/dot,
you`re in phase. Yes, it`s as simple as that.

~SNIP~

That's the ticket.

Do the valve adjust with the belts off.

Set the piston at TDC for the valves you're working on.
Cam drive pulley dot lined up with the hashmark, horizontal is ~TDC.
Cam drive pulley dot at ~9 O'Clock, vertical is ~TDC.
Don't rotate the crank unless you're sure all valves are closed.

[nomadwarmachine]

Thanks, everybody.  Adjusted the valves with the belts off this weekend.  So much easier to tell whether the closers are right and no worries about the valves dropping into the cylinder!   Bike is running great, though it idles a little higher than before.  Thoughts?

[Rob Hilding]

Thanks, everybody.  Adjusted the valves with the belts off this weekend.  So much easier to tell whether the closers are right and no worries about the valves dropping into the cylinder!   Bike is running great, though it idles a little higher than before.  Thoughts?

Same thing for me - I was advised to check TPS..........

Though I never did get around to it

[Speeddog]

If you tightened up the closers, the engine is trapping more air, as the valves aren't leaking as much.

Sync the TB's and set your idle speed.