Help! Noise in my engine

[Ranamow]

My engine...

Where I pointed out is that the noise occurs

Make sure the engine mounting bolts are tight. I had a guy come by thinking his engine was about to blow up. It ended up being loose engine bolts.

 

[Scrubcadet10]

really sounds like the valves clattering, to me.
I've always adjusted valves with this method:
Exhaust valve OPEN (exhaust rocker down) ADJUST the INTAKE.
Intake valve open (intake rocker down)adjust EXHAUST valve.'

 

[Bange]

Ranamow​

Screws that close the engine or those that secure the engine to the chassis?

Scrubcadet10
Allow me to disagree ... I don't see how a subtle mismatch in valves can cause noise in the crankshaft or connecting rod ... the same happens in cars ... When I speak of subtle noise, it is because it will always occur ... less when the adjustment is correct and a lot when out of tolerance. Valve noise is a frequent tic tic tic and on crankshaft or connecting rod, it is a heavy tuc tuc tuc less frequently ... do you understand what I mean? It's an analogy I make to ordinary cars, I could be wrong ...
The method you describe is correct, but generic ... there are design specifications that must be observed for the best performance, such as the difference of 1/4 inch in the exhaust.

 

[Scrubcadet10]

I believe ranamow is referring to the bolts that hold the engine to the frame.
if it is in fact the connecting rod knocking due to excess clearance , not much you can do.
On occasion i have seen the counterweight make a knocking noise. since he link arms are attached to the crank. however it appears there aren't any bearings used on the crank journal for the counterweight.

 

[Bange]

I understood...
In fact, I didn't see any bearings with balls, cylinders or bronzine, and if there is excessive play, both parts are exchanged.
I saw a guy (video) assembling one of these and an axial clearance appeared, I will see if it is my case ... in any case, to resolve it has to open and this is my problem, because here there are not thousands of units and dozens of stores like in USA, so the price is high ... there is no mystery to do. My question is whether there would be any procedure that could help in an evaluation ... Well, I'm going to see the screws that hold the machine and shoot something I noticed, but I don't know if it helps ... I'll be back soon ...

 

[Bellcrank]

Think'n a rod knock would change with engine rpm increase / decrease.

 

[Bange]

Well, in practice this happens, but when recording with increased RPM, the noise of the discharge increases (mufler), suppresses the TUC TUC TUC ... and it is not very clear.
In the video I forced a low RPM in order to make the TUC TUC TUC clearer ... did you notice?

 

[Bange]

Here I removed the spark plug and moved the flywheel ... turn up the sound to hear ....

Before anyone asks, the tape on the grid marks the TDC.
I never had contact with an similar engine in order to compare this noise...

As for the screws that hold the engine, they are like rock.
As for the axial clearance in the crankshaft, there is a little bit ... but it is not the cause of the problem

 

[Scrubcadet10]

Now what i would do is,
With the everything just like it is in the video, stick a pencil or wood dowel/screwdriver in the plug hole, see if there is any delay in movement of the piston relative to the movement of the crank.

 

[Bange]

I agree with the idea, but a millimeter gap that in practice results in a noise, I don't think it's noticed ... but I'll try ...
The ideal would be to hold the piston by the head and pull and push (impossible ...), even so I do not know if very small clearances would be perceived.
Wait for me...