White smoke, poor running - Curvy.

Originally Posted by maviczap

Not got a sticky choke plunger in the rear carb? I know you've cleaned the carb's but how about the plungers,

Well, with the first cleanout of the carbs, we also checked, cleaned and tested all that was connected to it: wiring, hoses, plungers, etc...
So I am pretty confident the choke plunger is fine..

But thanks for the tip!!

BR, Steve

So... this story has a funny tail to it:

After finding and installing a new (second-hand) carb, nothing seems to have changed, still the same problems.

So then I had no more clue what the problem could be.

By accident, when fiddeling some more around, the problem was mysteriously solved when disconnecting the hose that controls the fuel pump. Strange, so I wanted to confirm this..
I reconnect the hose and suddenly there is fuel running out of this hose.
Very strange, this is a hose were normall only air should ruun through...

Eureka 2: There is a leak in the fuel pump and through this way extra fuel is being sucked into the mixture!

An inspection of the fuel pump clears this and shows the rubber membrane that separates the air and feul has is worn out (=little wholes in it).

So on a sunday I was able to score another fuel pump and...
The back cylinder has joined the party again.

Just one more thing now; there are bing bangs coming out of the exhaust pipe, so the mixture is just a little poorly set. I cover the air intake of the carb with my hand, and the bangs are gone.
I reinstall the air filter and fuel tank -> no more bangs!
Surprising (for me) how the air intake is limited by these two!
So later I will have to carbs be re-adjusted for the ideal mixture and power, and this chapture can be closed!
(And meanwhile we have learned a lot again )

[muzikill]

Youve done pretty well tbh. How much do you think you could have saved btw if you had solved the prob straight away?

If I have solved the prob straight away, I would have saved about 175 euros...
But how to know this was a problem with the fuel pump.. Even you guys did not think of that, let alone me
Abyway, the new gastkets fixed the white smoke, so I do not see them as a lost cost.. Only the new carb.. ANd that one I can try to sell again.. So at the end, I spend about 100 euros...
If you can find me a mechanic who would make it as it was in its first state for 100 euros, please do
And now for you guys this is also useful info I wanted to share, so you know what you can test before buying a new carb