My bike has been getting harder to start when hot so i thought i would check the valve clearances. The problem is when i set the flywheel to the T top dead center mark the rocker arms are solid with no movement at all. Can this be correct? or am i doing something stupid.

That probably means you're not on compression but on the moment the valves are closing/opening.

Turn the flywheel one full revolution further and you should be ok.

Thanks for the reply, I have turned the flywheel over and am still in the same situation with no movement in the rocker arms at the T setting. On the F setting I am getting movement. Is it possible for that the valves could be that much out of adjustment and the bike still run. The clearances seem about correct on the F setting I am wondering now if the valves have been previously set on the wrong mark?

It sounds like the valves do need adjusting. You can tell if it is TDC of the compression stroke by holding your finger over the spark plug hole and rotating the crank. Compression stroke will push your finger away. Exhaust stroke will not because exhaust valve will be open.

Hard starting is a symptom of valves being too tight on a 4 stroke. Adjust the valves with cold engine at TDC of Compression stroke. Clearances per the manual for my '05.

Valve clearance:

Intake: 0.12 ± 0.03 mm (0.005 ± 0.001 in)

Exhaust: 0.30 ± 0.03 mm (0.012 ± 0.001 in)

I would be inclined to have someone who is fully familiar with these engines investigate this further. I have never had a 4RT apart but I have quite a few Honda 4 strokes. From what I know would expect the valve clearance should be the same on the TDC and F marks as I would not expect the lobe / lift part of the cam to be anywhere near at these angles.

It sounds as if the timing between the camshaft and crankshaft may be out. Possible causes are a partially sheared woodruff key on the flywheel or the camchain may have jumped a tooth or 2 on the sprockets.

I have even seen cam timing out when the crank had twisted due to hydraulic lock in the cylinder, because the engine sucked in water.

It is perfectly possible for an engine to run with the valve timing quite a bit out.

You'll find compression on every 4th rotation of the flywheel with the T showing in the timing hole. Hold a piece of electrical wire into the spark plug hole, feeling for piston at TDC and checking the valvues for movement. Keep repeating the process until you are happy with tdc on compression and T in the timing hole. Get someone to help as an extra pair of hands is useful.

The tricky bit is setting the clearances correctly as the feeler guage does not go in level and tends to snag quite a bit.

Take your time with it all, they're not impossibe to do. First time took me hours trying to sus the tdc thing.

You'll find compression on every 4th rotation of the flywheel with the T showing in the timing hole. Hold a piece of electrical wire into the spark plug hole, feeling for piston at TDC and checking the valvues for movement. Keep repeating the process until you are happy with tdc on compression and T in the timing hole. Get someone to help as an extra pair of hands is useful.

The tricky bit is setting the clearances correctly as the feeler guage does not go in level and tends to snag quite a bit.

Take your time with it all, they're not impossibe to do. First time took me hours trying to sus the tdc thing.

I think you mean every 2nd rotation

Does the cycle not go:

TDC to BDC inlets open

BDC to TDC on compression, all valves shut

TDC to BDC on power, all valves shut

BDC to TDC exhaust open

TDC on compression = every 4th

Those are the 4 strokes, not rotations

If I remember right, my manual had a supplement (loose page stuck in after the fact) saying to line up with the "F" mark, not the "T". The bike and manual are long gone or I'd double-check.

Thanks for all the replies, i finally got it sorted turns out that getting on the compression stroke was the problem. Once i managed that i had movement in the rocker arms and was able measure and adjust.