How important is honing the cylinder/piston/valves?

[digitalsam]

I cannot find a shop that is willing to check my cylinders/pistons and valves for proper specs. I am rebuilding the engine and want to know what might happen if I don't have this done. Am itching to ride, but would like to build it right if I can find a machinist, but prospects don't look so hot.

Any suggestions?

[tarzan]

Wow you cant find a shop just to measure to see?Do you live in one of those one horse towns.I would recommend highly if you are putting new pistons or rings or both to measure first.If the cylinders arent round still or are glazed or tapered they probably wont seal.Even if they do they wont live nearly as long as if everything is in spec.Also if you are installing new rings you need to at least hone the cyllinders.Another thing to consider is if you do not measure them you wont know if it is stock or overbored already and run the risk of buying parts that wont even fit. You can buy some cheap calipers for under $50 dollars and some telescoping gauges to check the bore for about $15-$20.Usually these are measured with a micrometer but you can do it with calipers.

[ccogswel]

Yes you will have to hone

Well it depends on what all you have done. To keep it simple I guess. I'll assume you are dealing with stock parts. If you torn the engine down then you will have to hone the cyclinder walls. You can buy that tool for about 25-30 bucks from just about anywhere. You need to do this in order for the rings to set in. If you don't then they will not set in right and it will smoke and the compression will be low as well. Now if you have a service manual like clymers or something like that there should be a guide in there with specifications for clearence's for ring end gaps, piston to wall, and so forth. As for the valves you can check them out as well. You can use simple tools. If you don't them some are cheep while others can get kind of expensive. But if you are having a hard time finding a shop to help out try your local Napa. If they have a machine shop I bet they will be more then glad to check things out if you give them the spec's. Hope this was some help. There will be others to chime in with more info too. Maybe even with better idea's as well.
Good Luck!

[petejw]

Hi Sam,
Why did you tear the engine down in the first place? was it making a noise? was it smokey? low compression?
If youre capable of pulling the engine apart its not that hard to check the specs of the pistons and rings, a feeler guage is all thats required.
To check your valves, tilt the head on the side, with the valves closed, pour petrol into each port and watch to see if it leaks or seaps between the valve and head chamber, if so depending on the degree of leakage, a valve lap or grind will be needed. If theres no seapage your valves a fine.

if the rings are ok spec wise, a honing wont hurt, just ensure a nice cross hatch pattern on the cylinder walls, you can buy cheap honing stones as stated before.

[Ivan]

You should be able to find a set of snap gauges pretty easily and check the bores your self. There is a plethora of information on the internet on hotrodding sites on how to do this.

As far as rebuilding the engine, I have learned that new rings in an old engine are a bad combo without honing. The device you are looking for is made from twisted wire and has a chimney brush look with spherical stones on the ends.



This type is not meant to take material, but just break the surface glaze. This will be fine to use if you are simply replacing rings.

On newer engines, the process of manufacture changed. They now use a process called "plateau honing" which creates the same surface finish as a well broken in engine, and almost eliminates the break in. If you end up needing your cylinders bored out, be sure and ask if the shop can perform teh plateau honing procedure. This combined with todays excellent oils has given me the chance to see many 150,000+ mile engines with so little wear in teh cylinders that the factory cross hatch was still visible.

[trbig]

Ivan...

Where do you find that style of honing brush? I looked for one when I was re-doing my engine.

If you talk to the guys that rebuild engines for a living, a correct hone is as important as the proper bore.

Tod

[tarzan]

I use the hone with three stones.It'll give a good crosshatch.I have used both kinds though.They both work in my opinion.

[Ivan]

Flex hones can usually be found at Napa or other independent parts stores. You have to buy the proper size for the cylinder. I wouldn't recommend Autozone or Oreilleys since they are the walmarts of the parts industry, and generally can't tell you where the 5w-30 oil is, let alone find a flex hone.

Tarzan, I agree that a traditional hone works well. Probably even better in the hands of an experienced engine builder, but for the first time guy with no experience, the flex hone isn't as aggressive, and is more user friendly. When only breaking the glaze, the surface is already conditioned, so an aggressive stone followed by a very light stone isn't really needed.

Either way, the important rules for honing a cylinder are thus:

Use shop solvent, instead of oil. Oil is sticky, and gums up the abrasive. Solvent moves the cuttings away from the stone. ATF (Automatic Transmission Fluid) isn't good either. If you can get some coolant from a machine shop, that would be ideal. Even some premix antifreeze is better than oil, if you have no other alternatives. I usually find an old spray bottle to put the stuff in and keep it flowing all the time. An assistant to run the squirt bottle is helpful.

When the hone is turning, it needs to be moving back and forth through the cylinder as well. traditionally a 60º crosshatch is desired. Don't rotate without moving.

Clean up is important. Clean the bores until a white rag doesn't show any gray stuff or glittery stuff.

I have rebuilt several engines, and this is the way I was taught. If it were my XS engine getting built, I would take the cylinder block to the local engine shop and ask their old hand to do it up for me. They will undoubtedly know more tricks than I do.

[Pat Kelly]

If you can't find a local machine shop to help you you can always ship the parts to a shop that wants your money. It will be more expensive and can be difficult to find a shop you can trust (I guess that can be said for face to face contact as well).
I have known the owner / operator of Yosemite Machine
http://www.yosmach.com/
for many years. He bored the cylinders on my LG for the 1196 kit. He does work on motorcycle engines.