Hi MWL9110, I looked at rods on eBay. That's a crap shoot with very poor odds!! At swap meet & cycle salvage, I looked at about 100 pairs of rods. They were all junk. Scrap metal really.
The guys at Rabers suggested steel rods vibrate more than normal rods even with dynamic crank balancing.
So it was basically no choice but new rods. Taking rod scale to shop for checking non matched rods, I found they were all over the place, even 10-15g different. The crank was getting dynamic balanced, but I was afraid they'd have to take too much off rods. So we ordered "matched set" LF Harris. The matched set weighed in at .1g. Basically spot on. Sadly the first set was dropped in the factory & had dent/gouge on the beam. 3 week wait for another set which was good. Was not expecting to speed $390 for new rod set, but that's the cost of ownership as they say. Proved $$ well spent in the end. You certainly want to quality control rods when you get them. Assume nothing on new parts. Each must be carefully inspected.
The new Harris rods have a beefier big end transition to shaft. Slightly beefier at small end. Heavier overall, but the heavy is mostly in big end so that's rotating mass compensated for in the balancing. Comes with new rod bolts installed with plain nuts holding them. Lock nuts were finger tight on ends of bolts. I'm scared of things backing off. I used loctite blue 243 on lock nuts during final assembly. I used torque wrench. I couldn't get repeatable readings with bolt stretch. Rods cleared cams, cylinder base etc. just fine. Didn't need to grind or modify anything. Used bolts & lock nuts that came with rods.
The motor was as shaker before, very uncomfortable at 65-70mph. Would burn you skin from vibration. Had .020 over pistons, looked like original Triumph. 7g different left to right. Original rods about 7g different left to right. Both heavies on same side. In the end after balancing the motor is dead smooth at 3800. Uncanny smooth. At 65-70 very acceptable, but you'll never get a Triumph twin smooth as we'd like. Shop took a lot of metal off the right pork chop on crank. I don't have advise of balance factor. We use 68%. I'd probably go higher percent next time.
You want to fit cleaned sludge trap to crank before balance. Don't stake plug yet. Remove trap after balance & reclean everything. Our balancer shop is a good place, but with grinding etc. there was like 4-5 specs of metal in oil way to journal. That would have damaged inserts. After cleaning crank again, I staked plug. I always use sealant on plug threads & look at the oil drilling below plug. Do the math. Don't allow plug to even partially block oilway.
I found weighing LF Harris, Emgo pistons, they were very close 1-2g or less. Several sets. The OD of pistons were very close as well. .0002". I don't know who makes these, but the quality control was amazing on the examples I checked. Piston pins fit pistons tightly cold. Heating pistons hot, but not yet spit boiling, the pins slid in nicely. I used heat gun.
On New Years day, motor will have covered 10k miles in 3 years. Several 300 mile days, from 32f to 110f. I'd use the Harris rods again.
Don
