Went and saw my guru today, the motor was not .040 over, had a B stamp..... but the oil rings are shot, the piston walls scorched, and the pistons coated black. Well, I was doing a top end anyway. Now the advice I need is to do a complete rebuild or wait and hope. I have play(side to side) on the front connecting rod. but the"boss" sez its not too bad, but what worries me is there is play in the rear rod and when you move the front connecting rod (side to side) you have movement in the rear connecting rod. This indicates (I Think) Either problems with the flywheels or the crank pin. So what would y'all do? rebuild (about $1500) or just the top end (bout 400-500) Thanks Dusty

 

If I were going to keep it and planned to put on lots of miles, I'd do a complete rebuild.

However, if I weren't in love with the bike, I'd do a quick top end and then sell it and use the money saved to buy a late model EVO.

 

I've been told by a good mechanic that a little side-to-side rod play is nothing to worry about. Vertical play is the big no no. I did a top end job on my '83 a few years ago and got excited about the side play I found on mine, but after talking to this mechanic, I put it back together with new pistons, rings, and a cylinder hone job and it's doing fine. That was over 25,000 miles ago.

 

Sounds like you are indeed in need of a top end job. The oil rings must be worn to the point they have blackened the piston skirts, along with some scoring on the cylinder walls. Bore the cylinders oversize just enough to clean up the cylinders, no more than that.
Your crankpin bearing is a bearing that has three sets of rollers in cages on the crank pin. The front rod sits in the middle on the middle row of rollers. The rear rod is forked to surround the front rod. The rear rod sits on the outboard pair of roller bearings on this same crank pin.
It is really difficult to measure wear of the bearing. If you disassemble the crank to inspect the bearing you will not find much unless the rollers or crankpin is really roughed up, and if that were the case then you would have known it before now.
Here is my opinion on doing the bottom end: If the rods feel like they turn smoothly on the crank, I would consider them good to use. These are roller bearings, not babbit bushings. They always have a constant flow of oil around them, so I think they should be good. If you have 75000 miles on the bike and want to spend some money, then rebuild the lower end. Otherwise.....no.
If it were me I would rebuild the top end only. You know for a fact that this needs to be done.
I would also remove the timing cover and the camshafts to inspect the lobe condition. Yeah, I know....the lobes can be inspected without removing the cams, but by removing them you get to look around the oil pump, idler gear and breather gear atop the pump. Replace any cam having a worn or pitted lobe. A used cam is fine as long as the lobe is smooth.
Be sure you understand fully how to retime the breather and the camshafts before you take it apart! Also watch as you remove each cam.....there are going to be a number of spacer washers on each cam. Keep them in place with the cam and do not mix them with other cams. These are there to establish the correct end play in the cams. The washers are either .005 or.007 inches thick and expect to find a combination of each on the cams...........pg

Edit note: Maybe I ought to add that the connecting rod fit on the crankpin is .0005 to.001. We are talking about up and down play here. No way you are going to detect up and down movement using your two hands as the dial indicator.
The side to side play of the rods is greater. When the pistons are running in the bores they are in place and move side to side as the piston end shifts. The up and down though is supposed to be that .0005 to .001. Greater clearance is going to let you know with a loud continuous knocking. Then it will be rebuild time for the lower end.

 

Off topic.... PG that is the sweetest looking Iron I have ever seen.

Back to the question, a top end rebuild is cheap and easy. Unless the crank is wrecked, just do the top. If you have to do a complete build, a crate motor is almost as cheap, and you get a warranty.

 

Where do you get a crate Ironhead motor? I'll take one, please.

 

Bob MacKay, I'll get his number and PM you. Best Iron man around.

 

So this guy has new Ironhead motors?

 

You can check for vertical movement by grabbing the con rod with one hand holding with upward pressure, with your other hand smack the top of the con rod, if you hear a deepclick, or knock, itsbearing time. (old porsche trick)

 

Yeah, he moved this year from Shallow Lake to somewhere around Kingston. I have his number at home. Cool guy, who forgot more about bikes than I will ever know.