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

[williampkerr]

Has it been standing? If so, how long?

But, yes, hone for sure...

She has been non operational for 10 years or more. I figured that honing the cylinders and lapping the valves was good general maintenance on this bike that is 33 years old. Either way, I'm knee deep in it now. Any other suggestions while I have the top end dismantled?

[tkent02]

I didn't check the clearance before taking it apart.

Too bad, it probably would have worked fine. They almost always do.
Cleaning is best done by riding it hard.

[Flyboy]

Yes, too bad, giving it a good hard ride would have brought those compression numbers right up to where they need to be, but like you say, in to it now.
Don't cheap out on the base gasket, you really don't want to pull it all apart again due to a base gasket oil leak a year down the road, and the cheap ones tend to do that.
Other than that, it is all pretty straight forward, not a difficult job at all, post updates so we can follow the progress..

[Ton1959]

I used to hone but it is better not do to it. But it is your choice.

[tkent02]

I used to hone but it is better not do to it. But it is your choice.

How do you figure?

[Ton1959]

A hone is not required and only gives you more oil consumption. Just put new rings in or clean the grooves and put the old rings back. Unless you can make it a very very light hone.
And do check valve guides as just putting new seals on worn guides is not going to do a lot. You only need that hone after a rebore really.

[tkent02]

New rings, or old rings if I don't know how the comperession was, I'm honing. A few seconds with a bottle brush hone isn't going to cause any oil burning.

At least it never has on the engines I've put together.

Grinding away at it halfway to the next overbore maybe.

[Ton1959]

But it won't make the compression higher that I do know. It just make the resistance for the rings a bit higher which you feel when you turn the engine over by hand. If you like it do it .

[tkent02]

It can make the compression higher if the rings never seated properly the first time.

[Nessism]

A hone is not required and only gives you more oil consumption. Just put new rings in or clean the grooves and put the old rings back. Unless you can make it a very very light hone.
And do check valve guides as just putting new seals on worn guides is not going to do a lot. You only need that hone after a rebore really.

I always hone with new rings. Don't think they will seal if you don't.

The question is whether it's necessary to hone when reusing rings. Personally, I don't think it should be done unless you have a specific reason for honing - removing some surface rust on the cylinder wall for example.

[williampkerr]

I always hone with new rings. Don't think they will seal if you don't.

The question is whether it's necessary to hone when reusing rings. Personally, I don't think it should be done unless you have a specific reason for honing - removing some surface rust on the cylinder wall for example.

My rings are in spec. I have been debating whether or not to hone. I have cleaned the pistons and lapped the valves. My first top-end overhaul, so trying to do it right. Pretty proud of the cleaned up pistons.

[tkent02]

How was the compression before? Looking at the black around the piston's wrist pin area, it may not have sealed all that well before. Maybe the original owner babied it during break in or something. My 450 pistons are completely clean below the top compression ring, I know it's rings were sealed well.

I'd hone it lightly and break it in hard to get the rings to seal.

[williampkerr]

How was the compression before? Looking at the black around the piston's wrist pin area, it may not have sealed all that well before. Maybe the original owner babied it during break in or something. My 450 pistons are completely clean below the top compression ring, I know it's rings were sealed well.

I'd hone it lightly and break it in hard to get the rings to seal.

Warm engine, dry compression test: compression on 1 and 4 was around 80 psi. Compression on 2 and 3 was around 120 psi.

Warm engine, wet compression test: compression rose across the line by about 20 psi.

I think a lite hone would probably be beneficial.

[tkent02]

Since you don't really know why the compression was on the low side, it sure couldn't hurt to do it. Lite being the key word here. Not going halfway to the next size, just a few seconds in each bore to get the cross hatch pattern.

[Ton1959]

Have a read

http://www.snowvalley.20m.com/bikes/dnthone.htm