Power Problem 1999 720cc

[mikidymac]

Based on your compression numbers and cylinder shine I would say your cylinders and pistons are well worn and should be bored oversized and larger pistons and rings fitted.

You also like your engine was running really rich.

 

[arsenic]

Thank you Mikidymac

So, based on your picture = cylinder 1 is too rich and cylinder 2 too lean.

But how do you adjust the richness individually on this carburetor? Do you have to play on the Needles?

Regarding cylinder 1, I don't know if you've seen it, but some material has gone where you can see my finger on the photo.
There are risks of water leaks ...

Is it repairable or should I absolutely go on a new cylinder?

Thank you for your precious help

EDIT : What do you think of a repair with Epoxy aluminum paste in order to repair the cylinder? (I show the location of the possible future leak with my finger).

Also I'm afraid to remove the nuts from the cylinder ...

I don't want them to get stuck. I thought about draining the water, filling with white vinegar overnight then draining the white vinegar and filling with WD40 one more night

 

[mikidymac]

I would replace the damaged cylinder with a good used one and have both cylinders bored to the next oversize with fresh pistons if it was mine.

 

[NickCawks]

I'm gonna agree with miki on the repair. We have seen people try epoxy repairs here and there but ultimately I consider them to be temporary fixes.

You don't want to be back in the repairing it again.

 

[arsenic]

Hi friends !

Thanks a lot for your answer

So I carried out a search for cylinders for my 720 ... Unfortunately for the moment I can only find seller whose prices are too high for me (more than 250 € per used cylinder ...) So I risk embarking on the repair of these for the moment ...

I start to desalt the parts, to scrape, to rub ... I notice that the cylinder head has a few points of the beginning of rust at the level of the cooling circuit. So I remove the damaged material, and I will try an epoxy dressing and sanding in the rules of the art.

I wondered about the internal cylinder head cooling circuit. Can this be treated with anti-rust paint in order to avoid an amplification of the oxidation points? Isn't that likely to prevent proper cooling of the engine? What do you think ?

 

[arsenic]

Hi friends,

I dismantled the cylinders, they were realeser.
Now I have to buy a piston kit, which one do you recommend? EBay? Other sellers?