Cylinders - To hone or not to hone, that is the question

[Guest]

I'm overhauling the top end of my '81 GS850G that has 30K miles. I've removed and inspected the cylinders. They are definitely smooth (some people will say they are "glazed", which my definition of the word 'glaze' isn't an accurate statement, but I digress) and the cylinders don't appear to have any gouging or imperfections. I've read conflicting opinions about honing cylinders. Some say yay and some say nay. What does this trusting community of GS riders have to say on this matter? To hone or not to hone, that is the question.

[tkent02]

Hone if you want any compression.

[AJ]

Definitely hone the cylinders. The rings and cylinders have to wear together to make a good seal. If you turn the rings in the grooves (as you inevitably will), the rings will no longer line up exactly the way before you took apart the engine. Honing the cylinder with a flex hone ("ball hone") breaks the glaze and creates a new cross hatch in the cylinder walls. The rings and cylinder walls can now wear together to make a new mating pattern.

Not hard to do and the hones aren't expensive. This link looked good.

http://www.enginehones.com/technical.html

[azr]

Hone.........

[rustybronco]

Definitely hone the cylinders. The rings and cylinders have to wear together to make a good seal. If you turn the rings in the grooves (as you inevitably will), the rings will no longer line up exactly the way before you took apart the engine.

Sorry to say but the rings in an engine never stay stationary.

Two strokes are pinned so they can't but 4 strokes can and do.

[oblique]

Dont modern engines have special superhard coatings on the cylinder walls?

https://en.wikipedia.org/wiki/Nikasil

[Steve]

Dont modern engines have special superhard coatings on the cylinder walls?

https://en.wikipedia.org/wiki/Nikasil

Yes, some MODERN engines do.

However, you would have to really stretch the imagination to call a GS engine "modern".

.

[megatwin]

The key would be to" lightly" hone the cylinders,just enough to break the glaze and get a cross hatch pattern.
I have seen them honed nearly to the next over size.

[williampkerr]

Thank you very much

[850 Combat]

Just curious, why take it apart at only 30000 miles?

[tkent02]

Just curious, why take it apart at only 30000 miles?

I figured it was a typo and he meant 300,000.

[williampkerr]

Just curious, why take it apart at only 30000 miles?

I'm new to working on motorcycles, so I'm learning as I go. I did a wet and dry compression test and noticed the compression rise with the wet test. 1 and 4 cylinders where about 80 psi while 3 and 4 cylinders were about 120 psi on the dry test and each rose about 20 psi on the wet test. A friend suggested I inspect the cylinders and rings and valves, which I'm in the process of doing as we speak.

[tkent02]

I'm new to working on motorcycles, so I'm learning as I go. I did a wet and dry compression test and noticed the compression rise with the wet test. 1 and 4 cylinders where about 80 psi while 3 and 4 cylinders were about 120 psi on the dry test and each rose about 20 psi on the wet test. A friend suggested I inspect the cylinders and rings and valves, which I'm in the process of doing as we speak.

Did you check the valve clearances before taking it apart?
Poor compression is almost always due to neglected valves.

[Flyboy]

Has it been standing? If so, how long?
Riding the snot out of it for a while will bring those numbers up if she has been idle.

And yes, Dale is spot on, rings do not stay stationary in the pistons, they rotate in the ring grooves all the time, so it is of no consequence how the rings are fitted.
I have seen people spend silly amounts of time tryingto stagger the ring end gaps perfectly, just wasting their time.
After the first two minutes of running, those ring gaps are no where near where they were when installed.

But, yes, hone for sure, if you doing a top end refresh, don't do a half job, also thought it was a typo, at 30 000 miles the motor is only just run in now.

[williampkerr]

Did you check the valve clearances before taking it apart?
Poor compression is almost always due to neglected valves.

I didn't check the clearance before taking it apart. The valves definitely needed cleaning though. I have cleaned them and they appear to be in good condition.