Amal Carb Jetting

[George]

I am inclined to agree with Bill. A photo of spark plug would be helpful. Simple test is to put finger in end of silencer finger black and sooty to rich black and oily burning oil or breather blocked. Some time ago a friend got his bike out after being in storage for over a year and had similar issues to you. After much work with no cure the problem was solved when we found that a squirrel had used the silencer to store it's winter supply of food.

[Mike]

Picking these messages up from a hotel bar in Switzerland after several long and very wet days on a rental bike.

Interesting stuff indeed. The plug was definitely black and wet. I cleaned it off as a matter of course, but didn’t think at the time that it might have been oil, but just sooty.

I have it on my workbench at home, so when I get back next week will have a closer look. I have no problem popping the head off for closer investigation if that becomes necessary.

Thank you all for the engagement and discussion!

Mike

[Mike]

we found that a squirrel had used the silencer to store it's winter supply of food.

Ha! I had exactly the same problem with a set of 888 exhausts some years back.

[Mike]

Decided to pull the head for inspection. Initial inspection shows a clean combustion chamber (I'm not surprised, given the low miles that I've done since the engine was rebuilt some time ago) - but there is definitely a coating of (clean) oil on the piston. Both valves are sealing quite well, which is good, but there is substantially more carbon around the exhaust valve. Popping the barrel off, the rings look fine, and the barrel is pretty good. There are a few light marks on it - but nothing so much that I'd worry about.





Looking at the valve seals, I appear to have two different colours, so looks like they've been replaced at different times. Without further disassembly, both *look* fine, but it could be hiding something. I'll continue the stripdown tomorrow, I think.

[George]

Worn / damaged valve guides and / or valve stems?

[Mike]

I'll start a new thread for this, because I think we've moved on from Amal Carb Jetting, into a complete top-end refurb..