Topic: 550 compression

[rook550]

I have recently aquired a 77 550 and did a comp test and read 120, 80, 80, 100
Does this mean the heads ect need to be redone or can I throw this thing together and run it?
thanks...

[Jay B]

That's a lot of variation. In a normally wearing engine the cylinder compression should be pretty close across the cylinders, within 10% or so. Try this- pour a little oil in each cylinder and take another test. If the rings are bad/stuck, the oil should seal them up and give a higher reading. If it's valves, the oil will have little effect. How far down do you have it tore apart? Oh yeah- make sure you have the throttles and chokes wide open when you do the compression tests.

[SteveD CB500F]

And the engine warm.

When I bought my 500 in 2001 it had 3x110 (ish) and one at 90.  I have ridden it ever since...

Now that the gearbox has broken, I guess I'll sort the compression as well.

[rook550]

I haven't payed a dime for this bike, I aquired it through a car purchase deal...so I haven't tore it down yet I was hoping to not have to get too deep into the engine if I could avoid it..I am wanting to get this bike running and to get the" cafe racer" look, I am not too concerned on the power performance aspect as of yet( it is only a 550) I just want a cool looking commuter. I was in the process of saving for a 2001 release of the KAWI W650 but I ran across this bike in the meantime, so my goal is to spend under 1000K to get it to the point I want, but if need be I am willing to dive in and learn...thanks for the replies everybody...

[Jay B]

Well, if it's all together you could just get it going and ride it a while. Maybe use an additive, many like Marvel Mystery Oil, I've had real good luck with Yamaha Ring Free. If it's been sitting, running it some might loosen up the rings if they are stuck. I think that's what I'd do- get it up and going then play it by ear after that.