Wrong forum - Gen1 Compression lowered in cylinder #3

[Erga]

Got myself my first V-max last summer and I've been so far really happy with the thing. However seems that I've run out of luck as I started feeling momentary power loss and exhaust popping when driving on stable revs (2000-4000) in the beginning of summer. After some investigation the spark plug in cyl #3 was pitch black. Swapped the plugs without any improvement so I decided to take it to a shop. They confirmed that cyl #3 is not having proper pressure so it is leaking it somewhere. They checked coils, valves, cleaned carburetors and changed a load of gaskets but nothing helped. So they gave up...

Before I take it to another shop and pay another 1000 I figured that I might as well seek some help from forums if people have had similar issues. Any advice where to start looking for the culprit would be highly appreciated.

 

[Fire-medic]

I suspect you've posted in the wrong forum section. The Gen.1 has carburetors, the Gen. II is fuel injection.

'Facts are facts... .' What are the cyl readings? From what you're sayin' I'd expect there would be a big difference from the other 3 cylinders. So #3 should be 'way low. What's the reading? Once you know what all 4 read, then you can do a quick diagnostic: squirt some oil into #3 and re-do the cyl compression test, If the reading rises significantly, you probably have bad rings.

Then a leak-down test can help to determine if it's intake or exhaust, if the reading doesn't change much, leading you to suspect something in the valvetrain. With the cyl pressurized, air leakage at the carbs (throttle held open) says intakes, while air leakage at the exhaust suggests exhaust valves issue.

An oil fouled plug says to me piston rings or something like a missing main jet unscrewed from its jet block location. Did they disassemble the carbs to clean them? It's a good idea to ask for whatever is replaced to be returned to you so you have an idea of what has been done. I'd want to know, "what is a 'load of gaskets' and what were the locations from which they were removed?"

 

[Erga]

Sorry, you are right, Wrong Forum, I'll move this to correct place and will add info there.