@Suuz Can you elaborate on the extent to which the carburetors were cleaned? How much of a disassembly was performed during that service?

 

The carburators where disassembled completely and where ultrasonic cleaned.

 

@IDoDirt do you have any suggestions?

 

If you have a good spark and you have compression, that pretty much only leaves fuel. I remember when I first got back into riding and working on my motorcycles, it took me 3 time of taking my carburetors off, cleaning and inspecting them and putting them back on before I got it right.

 

Oké. That confirms my idea of how to approach this. Namely that my first thought could still be right and that I start from the beginning as if nothing has been done yet.
So I start cleaning my fueltank, pump and filter and make sure a have fresh fuel in a clean jerrycan at hand.
Then I will clean the carbs myself (instead of letting someone else do it) so I can check every step.
Then put everything back together and see if she'll finally run.
​

 

It might help eliminate some of the possible problems if you tried to start it using an a gravity fed auxiliary fuel tank. If she still doesn't start, then this would certainly point to the carbs. Esp as you will be taking the tank off anyway.
The tank could probably do with a clean as you suggest as the internal fuel filter could be perished / clogged. I did notice that you has an inline fuel filter as well, have you checked to make sure that is clean?

 

To back up what others have said, if you take a look back through the different forums on here there are countless times where people say, "my carbs are clean, I know it" only to find out that they in fact need to re-clean them. This is the issue the majority of the time. The carbs are amazing but do demand to be spotless.

 

You mean the filter inside the fueltank?

 

Yes, there should be a filter inside the tank which sits around the petcock fuel pipe as is shown on the picture below:
https://www.aliexpress.com/item/1005...rch-mainSearch

 

Well, great minds think alike. :-)
​​​​​Before I read your post, I took out the fuel **** (I believe it is called) and took the screenset out of the tank. That was quite a job because the screenset had some sticky stuff that sticked it to the tank. It was good I took it out...

Fuel tank filter https://imgur.com/a/PQwURJD

Next step is to clean the inside off my tank and seal it to prefent it from rusting again. Than I will clean the fuelfilter close to the fuelpump. Than I will clean the carbs.

I'm thinking about buying a ultrasone cleaner. The are not that expensive. How large should it be for the largest part to fit?
I might even buy old, cheap carbs so I can use them to learn how to do it without damaging my own.