Hi everyone, Just took my 1972 LT2 out for the first ride since getting it running recently before handing it to the kids. New clutch plates, carb clean out and rebuild kit, fixed leaky petcock, oil leak, plugged exhaust, etc. starts first kick, idles perfectly but barely climbs a minor hill in anything but first gear. Fine on flats and downhill. Some hesitation at higher rpms like it still needs to get to full operating temp but never gets there. I doubt these small bikes were ever powerhouses and I do add 185 lbs to transport. My instinct is it’s probably time for a top end but maybe there are other culprits. Any advice would be most welcome. 

Brassware in carb kits is not to be trusted, always try and fit original. If it is a Mikuni, then most brass parts are still available new.

Gaskets from the kit should be ok, though.

Also, is the air filter clean and not over oiled (if the oil type)?

I kept the original brass and can put back in as a test to be sure. Air filter seems clean and I haven’t re-oiled it yet. Sounds as though you think it may be fuel/air delivery over top end. I haven’t done a compression check yet. Picking up a gauge today. 

Points closed down below 12 retarding the timing. give it 14-15 & try it. They were a bit revy those models so have to wring their neck through the gears.

What are you running for an air filter?

Also inspect your plug to see if you are rich or lean. Rich would cause what you are describing.

hi Mark, so appreciate your input on so many of other's posts. I learn so much from what you have to say.
It's the original chrome filter box with a foam filter wire tied around what I think is the original internal screen. I cleaned it and reoiled it. (I didn't have any PJ1 or other of the recommended oil treatments so I coated it with motor oil). I know this is contrary to what nearly all posts suggest so I'll mitigate that as soon as I can.

It's a new NGK BR8ES. I have a sense it is running rich but I'll pull the plug tonight to verify. Just did a compression check and showed a solid 120 psi after about 10 kicks. I had soaked the pipe in a can of B12 for several hours then drained and heated it a bit several weeks back. Some solids came out with the liquid. Still felt heavier than I thought it should but there may have been some residual B12 remaining at that point. Seems this issue may be pointing back to carburetion. Hope to pickup an ultrasonic cleaner soon. I've only been using the B9 dip method at this stage. Ran wire through all the passages and blew out. 

Time for me to learn how to do a proper timing set. 

Owners manual calls for NGK B8HS plug. Not sure about the resistor plug being compatible with the old magneto ignition and the BR8ES is longer.

 

Also try the air filter without oil.