Technical 500R engine stops when hot

[britbe]

Hi all,

I have a new issue with my 500R.
The car starts ok, even after a while not driving with it, but after about 2-3km, when getting a bit hot, the engine stops running and I can't start it again until it coolded down for about 5 minutes. Then it runs again for 2-3km, same and same again.

I did some research and found that a fuel return line could solve potential fuel to hot issues?
But when I look at the engine, I have a IMB28 carburator with already a fuel line installed? Should I renew it?

What I've recently done :
- Rebuild the carb
- Build in a electronic ignition

When I look at the fuel pump, looking at the gaskets, it seems to be relatively new also. Or should I replace it anyway to see if this is the issue?

Other ideas? I also have the impression when the engine is running hot and I stop it, the oil is 'boiling', at least I hear that kind of sound, but I think this is normal?

See pictures of the fuel return line on the carb and the fuel pump.

thanks for helping me sorting this out!

Grts
Bjorn

 

[smart51]

It could be that the valve clearances have closed up. There is a gap between the push rods and rockers when the engine is cold. When the engine heats up, the parts expand and the clearance reduces. If the gap is not big enough, when the engine heats up, the valves won't close fully.

 

[britbe]

Ok, thx.
I found this, is this correct to set the valve clearance:

Inlet: .0078" (.20mm)
Exhaust: .0098" (.25mm)

 

[smart51]

Ok, thx.
I found this, is this correct to set the valve clearance:

Inlet: .0078" (.20mm)
Exhaust: .0098" (.25mm)

That's what I set mine to.

 

[britbe]

Just to be sure: I need to set this with a cold engine I suppose?

 

[smart51]

Just to be sure: I need to set this with a cold engine I suppose?

Just to be sure: I need to set this with a cold engine I suppose?

That's what I did.

 

[britbe]

Great, thx!