Hello:
I have a set of 1340 cylinders which are stock bore. the walls look good no heavy scaring and are 3 thousands out of round. I was wondering if I could use a ball hone to scratch them back up and put the stock pistons with new rings back in, or would I have to have them bored to the next size.

 

The book says 3 is the service limit, but I don't think you really can make any meaningful assumptions unless you have the jug bolted into the fixture to compress it under the proper working torque as if it were bolted down on the case. If you do...then you are at the service limit. If you don't...you really don't know.

You have not mentioned the mileage on the engine or "why" you have these jugs. If they came off a bike that had no issues and fairly low miles, I may just hone them and install new rings, or possibly do nothing at all and put the existing pistons and rings back in, If they come from some unknown engine....I would certainly have them bored.

 

looks like I'm going to have them bored. Thought I could get by cheap,

Thanks you have been very helpfull

 

Don't let me talk you into anything. I have had EVO's apart with 50K on them and not even have the cross-hatch worn off the bore interiors. Then again, I have seen them well-worn at 25K. Plenty of times I have witnessed an HD Tech. take them off at 20-30K to replace a base gasket and just put them all back together like they came off. I think the secret would be the piston and rings and my point in asking where they came from was the reason for that. If you had no issues with the motor like it was and did not have a lot of miles on it, I'd be tempted to stick them back on like they came off. If they came from some other place, the wisest thing to do is make them new again and you will know what you have. You can't just take these to some machine shop and have them bored. You could likely get a .050 over set, do that and have no problems, but the recommended way is to have them torqued into the jig I mentioned above, which means you will need to have that done through a stealership or an Indy.

Have you shopped around like on e-bay for a set? You may could come up with a good set of jugs and pistons cheaply. If it were a Twin Cam...they would be more plentiful from ones left over after a stage II upgrade. I have a set of TC-88 jugs and pistons with less than 10K on them, but they would do you no good.

Good luck!

 

if you want a "new engine"rebore and oversize pistons.. if you hone the cylinders,clean(wirebrush)pistons,and use new rings you will get pretty good results, the rings expand to the cylinders even with some wear,that is what they are for..i have done it hundreds of times on my stuff or cheap customers bikes..it is ok if the cylinders arnt perfect, as long as there arnt any deep gouges or ridges that will damage the rings..it will never be quite as good as a rebore but a whole lot cheaper..

 

Shovelhead or Evo?

 

My two rules on thumb.

If you are going to pull the rings off the pistons to clean up the pistons, then pistons get new rings.
Hence even if all your doing it using the rings in the jugs to see what kind of gap they have. The reason for this, Harley does not use the locator pins for the rings on the pistons, and no mater how close you think that the rings are set back to old alignments on the pistols, are still not going to match up to the old alignments.
So on quick top end, never fully pull the pistons out of the jugs, but just enough to get the wrist pin out only, to leave the piston with rings in the jugs when the jugs are pulled.

Since I have a ring grinder to set gaps, then always will pick up .005" over size rings, so I can set the gaps to about .008. Don't go tighter than this, since Harley motors get hot when sitting at a light, and as the rings get hotter, the ring gap decreases. When rings to go zero gap, ends up with rings binding to cylinder walls, and pulls the top of piston off. If you use standard rings, and have a gap of say .016" with lower compression motors, still fine. Looser gap is better, than tighter gap that can cause a piston failure.

As for cylinders, if smooth with no cross hatching left (walls glazed), will need to cross hatch so the new rings can mate in.

As for rings, don't over think it, and since it came with Hasting rings to start with, just use another set back in.
Note, double check all the rings gaps in the cylinders. Although labeled as standards, they tend to be .005" overs, so will need to set gaps.

The last one, or really the first one, is chances are you pull the jugs due to gasket leaks. Best advice I can give you, find a shop that can chuck the cylinders up in a lathe to lathe cut off the old gaskets off, and square the top and bottom surfaces to the bore line at the same time to give the just a true gasket mating surface.

A ball horn tool will run you around $40, and its about the same amount of money that they will charge you to cross hatch the cylinders using a honing machine after squaring the mating surfaces,that will do a better job than that you can do with a ball hone. Hence start with Jugs mating surfaces squared/clean ups, then determine if the jugs need to be bored next size up or not, if you just need to swap in new rings on cross hatch cylinders since you pull the pistons out of the cylinder, or if you need new over size pistons and rings for the bored and cross hatched cylinder instead.

Also, gasket kit will come with new valve seals, so pull the valves to clean them and the heads up, do a quick lapping to lap the valves back into into the seats, and then install the new valve stem seal. On a 50K motor, valve guides should still be good, but just double check them against the cleaned valve stems to make sure you don't have excess slop.
Note, if you are using the JG gasket set, do not use the umbrella breathes that come with the set since they don't fit correctly. Go to Harley and pick up new umbrellas to use instead.




Simply, if your going to do a top end, take the time to do it right, so the motor does not have to come apart until it time to do a bottom end/rebuild the entire motor.

Also, with top end off, good time to pull the cam chest cover to change out the cam bearing is not a Torrington Koyo B138 in play,and if still running the A lifters, change them out to a set of Jonhson 2303's .

OEM's A;s on the right with thinner walls, while B's on the left with thicker walls to start with.
Also even with B's in play, make sure to check the rollers for flat spots, or roller very loose to shaft with lots of slop meaning time to change them as well.

 

Good stuff, unfortunately this post is 13 years old.. Hopefully the guy figured out what to do..