I removed my spark plugs to see how they are after i have done little more than a thousand km's. What do you think about them? It is a champion L82C,
have in mind that car has a lot of emissions that they come from fuel as i was told. I have clean/rebuild adjust carburetor, adjust valves and replace points with an electronic pic up. The car is very hard to drive since gas fumes are entering the cabin specially with closed windows:bang: so when i open the window more fumes come inside:bang::bang: No smoke is visible from the exhaust. I have the feeling that even if i rebuild the engine problem will continue. I also measured cylinder compression and it is 135 and 140 psi:slayer:
Another thing is that engine backfires when i release the throttle and i have try many different timing settings.

If those are the two plugs from the engine then the two cylinders are running very different. The plug on the left is running too hot, and the plug on the right is running a little cold. The compression pressures seem high for these engines. I would have thought something more around 120 psi.
Check the valve clearances first. Make sure that you have set the timing dynamically. That is, with the engine running at 3000 rpm. You should have 18 degrees advance.
John

It is the same plug actually taken with and wo flash. I have set valves to 015 and have adjust timing by hand. As any other user I have also conclude that 18 degrees is not good. Also both spark plugs have almost the same colour.

Valve seats is my concern although I have very good compression but it is something I have to check anyway.
Exhaust looks undamaged . Starting at winder was better than now we have 20 degrees plus, I was proud of my cold starting actually, now I am using my starting devise but I think this has to do with fuel pump.

gordinir8 said:

It is the same plug actually taken with and wo flash. I have set valves to 015 and have adjust timing by hand. As any other user I have also conclude that 18 degrees is not good. Also both spark plugs have almost the same colour.

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Thomas I think you have a 650 engine don't you. If so the valve clearances should be 0.20 mm for inlet and 0.25 mm exhaust.

As has been discussed on the forum, setting the engine timing by hand is the starting point to get the engine to start. You must set the engine timing with a timing light after the points are set correctly.
Backfiring is an indication that there is too much fuel in the cylinders, the timing is off, or as Peter indicated, there is a problem with a valve not sealing good due to being burned or clearance set too tight.
John

Paolo66 said:

Thomas I think you have a 650 engine don't you. If so the valve clearances should be 0.20 mm for inlet and 0.25 mm exhaust.

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I'm pretty sure Thomas has a 500 engine; a few people have answered as if he has a 650 but I think he's exploring the possibility of either upgrading to bigger cylinders or getting a 650 engine.

having said that I think there may be an advantage in setting the 500 clearances a bit wider than recommended because we all seem to be concluding (especially me!) that that valves and their clearances are the Number One go-to place when an air-cooled engine is playing up.:bang:

Peter you are correct i have a 500 engine, John many users from here have conclude that the 18 degrees of advance is not realistic in this engine, maybe has to do with modern fuels who knows but i believe that this has nothing to do with the high emissions.
Carburetor leaks from the butterfly shaft (i have done the wd40 test) but since there are no seals in the 26 IMB i wonder if this is a bit of normal or is the reason i have high emissions.

I am talking about emissions making tester go crazy and impossible to drive the car with closed windows, it just makes you sick my throat and my eyes can't stand it. I know that an old car can't be as clean as a new.

Hi all. I believe that John is spot on ,backfire is timing and I would guess that the valves must be badly burnt.

You can check for leaking valves if you can get compressed air into the spark plug hole.
With both valves closed and the piston at TDC, put compressed air into the cylinder through the spark plug hole. If you hear air coming out of the carburetor, the problem is intake valve, if you hear air coming out of the exhaust, problem is exhaust valve.

Leaking valves may explain all the fumes.
By the way, my 500cc engine has Pertronix electronic ignition, and the timing has been set to 18 degrees at 3000 rpm and the engine starts immediately and runs smooth.

John

I might do that John although i think i better remove head and take a better look. I have set now the timing to an unknown setting more that 20-22 degrees and the car goes better than ever (with all the other problems)