Main Motorcycle: 1978 Triumph Bonneville
Join Date: Mar 2005
Location: Houston, tx
I have the same bike, I think you will really enjoy it once you get it running. They are great riding little bikes with the 5 speed and disc brakes. Most people seem to think the JCC pistons are okay. Hastings cast iron rings probably a good choice and readily available. Hone the bore fairly coarse, like a 250 grit. Most people try to install the pistons with a minimum of oil on the bores to aid in break in. Also, avoid break-in oil with friction reducers like modern car oil. I'm using 15w40 Rotella diesel to break in a Commando I'm rebuilding.
There are lots of opinions on break-in oil. Do a search and you will get the idea. Once broke in use a 20w50 SG rated motorcycle oil for aircooled engines. These bikes share primary and engine oil and the SL and SM rated oil will cause the clutch to slip. Valvoline is what I use, but there are other brands. An add on oil filter is highly recommended. I'm using the one MAP Cycle sells. There is also the Norton Commando style. 90w gear lube in the gear box.
MAP also sells good clutch pack sets and they will really improve the performance of your bike. Plan on rebuilding the master cylinders and calipers. Kits are available. If you have the points sets and advance unit, you might hold off on the EI for a while. The EI units require a good power supply to run reliably where as the points will forgive some dodgy wiring or a low battery. Replace the zener diode and rectifier with a solid state unit like a podtronics.
Reliable parts suppliers I have used include Waldridge Motors, who are having their year end sale right now, British Only, MAP Cycle, Baxters and on ebay Steadfast Cycles.
I'd look for used side covers on ebay. A new set will be pretty costly.
Htown16, Houston, Texas
1978 T140E Bonneville, 1974 Trident, 1972 Commando, 1971 Commando
1974 Commando, 1970 BSA Thunderbolt, 2004 XL 1200R Sportster
Everything will be alright in the end.
If its not alright, its not the end.