R51/2 Adjusting the valves

[Goro F]

hello
right cylinder is doing a clicking sound which is not present on the left cylinder. I did a tool to check the balance of carburators and the right carb also shows a lower vacuum value than the left. I tried to balance without success

I never personally did the check of valves and i m looking at the maintenance handbook. I found some interesting video tutorial on the web but nothing specific for my bike model.

is there anybody that can provide me some technical tips to do it in the best way?

[Slash2rider]

You may have ticking noise from the rockers as well.

[Goro F]

What I do not understand is how to be sure that the top dead center is reached by piston by checking just that the air is compressed

[schrader7032]

Never heard that before. Typically, one removes the spark plug and use something like a chopstick in the hole. Then slowly turning the engine, find the spot in the rotation where the chopstick comes out the farthest. Observe the timing marks through the inspection hole. You can tell if you're on the compression stroke by watching that the intake valve opened and then closed. After it closes, the next point where the chopstick has reached the farthest point, that is top dead center. Top dead center for the other cylinder is one 360 degree rotation of the engine.

[Goro F]

Thanks for reply Schrader

What you re saying is also what I know. In the manual is not mentioned any timing timing mark to check while you re doing this job. Anybody knows where I should look on R51/2 model?

Remove sparkplug and insert a chopstick to verify top dead center, works also if the position of sparkplug is mounted on the side of cylinder and not in the center of the head?

[cbclemmens]

One little tip.

After you have set the adjustments and locked them down tight, turn the engine over several times, put the cylinder back at TDC and check the clearance again.

Craig

[Fred Heiler]

Hope you all like (or already use) my method, since it doesn't require messing with timing marks and works on any opposed engine:

With the bike on the center stand and in gear, turn the engine over with the rear wheel. With both valve covers off, observe when a pair of rockers are moving (both rocking, between exhaust and intake strokes). Then, adjust valves on the OTHER side, since that piston is at the top of the compression stroke, with both valves fully closed.

Turn the engine over and repeat the process to adjust valves on the other side. Removing plugs is optional; the engine is easier to turn over with plugs removed.

[schrader7032]

observe when a pair of rockers are moving (both rocking, between exhaust and intake strokes).

I'm not sure I understand what I would be seeing in this situation. "Moving"?

One thing that should be remembered is that if the valve clearances are significantly off when looking for TDC or the side to make adjustments, then you will be confused when things move or don't move because the clearances are messed up.

Another point regarding timing marks. On my R25/2, there was only a TDC mark. During the rebuild, Vech had to line up an R25/3 flywheel and transfer the other marks to my flywheel.

[Goro F]

I share what i try to understand.

Intake valve cam and output valve cam are mounted at 90° degrees shift on the cam shaft.

Shape of the cams are partly cylidrical, where the pushrods must not move since the both valves must be closed.

If what i write is right, it means that for some degrees (green common area highlithed in the picture) the cam shaft can be turned and the both pushrods do not move. Doesn’t matter if you exactly reached the top dead center of piston, it’s enought that you are in this range for making the adjustment of the clearance.

So, as suggested by Fred, with the bike on the center stand and in gear, turn the engine over with the rear wheel. With both valve covers off, observe when a pair of rockers are moving (both rocking, between exhaust and intake strokes). Then, adjust valves on the OTHER side, since that piston may be is not exactly at the top of the compression stroke or top dead center, but the camshaft is the position where both valves fully closed.

Am I wrong?