I did this: AFAIK all parts of carb was in its smallest pieces and I found nothing... Used guitar strings and put them in all holes, and used pessure air to blow all holes... Found nothing .. put it all tougether and then bike was fine. No problems...

So ... bike is now fine, and I don't know why ...

Did some tests today. I managed to get it to start, let it run at 2000rpm for a while, and it responds nice to speedhandle input... full range. It also ran at 1200rpm idle. When dieing I managed to get it to start again by holding full speed and then let speed go while running starter. Several times ...

Thanks for trying to help :-)
I had an incident with my back, and was in great pain for a week, sorry for responding so late.

Battery is good, and I recharge while and after trying to start.

Cleaned carb twice. New o-rings. Bike runs fine if I'm lucky enough to get it to start, but if engine dies ...

My 4PT (1998) engine runs fine, but if it stops it is near impossible to start again. It is also near impossible to start any time. But if I manage to start it runs fine.

I've cleaned carb twice, plug seems fine and is 1 year old.

Problem started instantly. Started it up easy, rode to shop, but ...

Thanks Mezo... still quite a lot of cash..

Still riding with that part missing.. :-(

I'll still make a copy in glass fiber when/if I get hold of one :-) Has anyone done that?
Also thinking of using moldable plastic (60°C or 100°C) (Could also be useful when making a inverse copy if I make that ...

I think it is this part number: 4PT-2137W-01-00
Found one new... but 133 EUR?
I'll make a copy in glass fiber when I get hold of one :-)
Not much on ebay.. That piece of plastic with most of the X on it.
Could also be interested in a bigger tank instead of replacing plastic
https://mcn-images ...

Thanks Mezo & behnix... I'll consider the options you mentioned :-) I think a list of mechanics would be great for more than me.
I bought my 34L (registered August 1983 in Norway (the oldest one in .no ?)) in 2012 with 51000km on it, for 6000kr (about 1000USD) changed clutch wire and rear brake ...

I live in Norway, and my bike is in serious need of some care. I'm afraid I'll have to much to do, and my skills also have to be developed during repairs. So I'm thinking of driving my bike or car (with bike on) to Sweden, Poland, Germany, Lithuania or other place. Repairs cost:
150$/h in Norway I ...

Bought this: http://www.ebay.com/itm/Yamaha-XT600-XT ... 3a96b35d82

Seller writes 34L and 43F use same parts...

Thanks for your effort both of you..

http://www.partzilla.com/parts/search/Y ... parts.html

Why is price of items for 43F half of price for 34L? (probably demand but, 2x or 5x? (kedo))..