First time freeing an engine- now what about these pistons?

[houseowax]

I bought a '65 CB a couple of months ago. then another. Then a '64 Dream and a '65 Dream engine. All are seized - well, were seized. Today my pal and I managed to free both the CB engines, ( penetrating oil for a month, then map gas, then thumping with a block of mahogany and a framing hammer) pull the heads and remove the pistons. The cylinder walls look OK to my untrained eye; no scarring and minimal surface rust. The pistons in both engines are standards and look fine but the rings are stuck in their gaps - I boiled the pistons and cleaned them up but the rings aren't moving. I thought to try soaking them in some penetrating oil but - am I wasting my time?

Is the prudent thing to do just to bore the cylinders and fit a set of 1 or 2 overs? And on that subject- I see Tim at Classic is offering piston sets in standard, 2 and 4 over. Any reason not to just jump to 2nd over and go with a brand new and allegedly 'far superior' set from Tim?

http://www.classichondarestoration.com/ ... rod_6.html

Thanks- Steve

[rustywrench]

Steve,
In all my years of wrenching on stuff I have come down to two questions you need to answer. Do you want to do it once the right way and not have to do it again, or do you need to just "get her running" for the time being?
The first would be a proper bore and piston fit by a professional machinist and the most expensive route.
The short cut way is to get those rings out of the groves, hone the cylinder walls and install the pistons with stock rings providing they end gap within tolerance and get her running. The cheapest way no doubt, but you would need to do it again at a later time.
I've been both routes for both reasons and can only advise you to decide for yourself and go with that. Those rings will come out BTW and that engine will run with those pistons. Just how long and how dependable it would be is up to you to decide. Rusty

[conbs]

In a recent post, Snakeoil talked about a commercial product made by B&G (?? or something close that) that will release those rings. It apparently dissolves carbon and rust. Be very, very careful with those rings. They will break really easily.

First things first. I would suggest that you measure your cylinders and pistons to see what you have. It would probably help you to post pictures and get some second opinions. When you run your thumb nail across the piston skirts do they feel smooth or can you feel gouging? If things aren't smooth, you will want a new bore/pistons. But even if you have a smooth surface, you need to know how much wear you have.

If cylinders and pistons are within the wear ranges, what will you "fix" by replacing them? If they are right on the edge, you may want to replace them, depending on how much you will ride the particular bike. If they are outside the wear limit, but not by much, you can probably still get the bike to run fairly well, but you may end up dealing with a little smoke and you will always have to baby the engine a little. If it doesn't cost you anything except a few gaskets and your time and you won't ride the bike that much, that might be a route to consider.

If you replace the rings, you will want to hone the cylinders to get the cross-hatch pattern. That may not take much, but it will begin to change your cylinder measurements slightly and will need to measure them again to see where you are. The wear limits are pretty narrow to begin with so you may be pushing things past their limit. If you go past the limits, as Rusty says, you will probably be dealing with it again in the future. But, if you don't ride the bike much, that could be a long time from now.

I think you have to figure out exactly what you have before you can make a decision. Even then, it probably depends. I realize what I have suggested is anathema to a lot of guys who work on these bikes regularly. But, they are in the business of making bikes dependable and can't afford to do things twice. You are in the business of having fun. If you are like me, working on your bike is fun, though not as much fun as riding it. So go have some.

I hope this helps you with your decision.

[48lesco]

I'd measure the bores to see if you can even use the old std pistons. If not, I wouldn't waste my time on the old pistons. You can warm them up and bust out the rings if you need to, you can't reuse them anyway because they lose their "spring" and won't seal very well. They are only good for cleaning out the ring grooves at this point.

OEM .25mm-over pistons and rings are available on ebay and elsewhere for less than $200 total and you can also find good used pistons for even cheaper. You can get the cylinders fitted to the new or used pistons at a machine shop for $50 per cylinder. If you have a solid hone like a Lisle or Sunnen and a bore gage you can do it yourself in a couple hours.

Check the big and small ends of the rods too. With some oil on the pins, the small ends should have no perceptible play. The big ends can have a little side-to-side slop, but you shouldn't be able to twist them or rattle them up and down at all.

Finally, I'd go with OEM Honda parts (just my opinion).
-48

[houseowax]

Thanks as always for the swift and thoughtful replies. I should clarify that I never intended to keep or reuse the rings, I only wanted to dislodge them from the grooves. I'll soak them in Kano Exrust and see if that does the trick. One of the CB's I intend to get running, spruce it up and sell off, the other I plan to do a complete job on and make it my daily driver. I expect I'll reuse the pistons on the one I plan to sell and fit the keeper with OEM .25's and have it bored out to fit.

While I've been told it's a relatively simple procedure to hone your own cylinders I'm not convinced I'm up to the task. I'll trust in the experts, although the last 'expert' I went to took close to 13 weeks to do the job. I'll look elsewhere this time.

[48lesco]

Sounds like a good approach. I'm all for better living through chemistry etc, but I would heat those babies up with a torch to just a little too hot to touch, and with the right gloves, see if the rings don't free up a little.

BTW - I have a set of standard rings that have about 1000 miles on them. If they would do you some good, PM me and we'll negotiate but I'm not that good so you'll probably get them for cheap.
-48

[houseowax]

Thanks, 48. I'll get back to you on that one when I have a better idea of my next step.
The 'right gloves' should be high on my shopping list. When I was freeing up those pistons I was in charge of pulling up on the cyl head while my pal was the dedicated hammer-and-block man. All I had was a pair of construction gloves; the blue-palmed cotton jobs. Even with the aid of a thick rag I'm fairly certain I've forever burned off my fingerprints.
But hey, the pistons got freed, and that's what matters.

I guess I'll have to get those jugs over to an engine shop and see where we stand. Might be a while though- my car's down to the reserve tank, the closest engine shop that I know of is about a 20 min drive and the lines for gas are over 4 hours. Hurricanes! Nor'easters! What next?