Welcome Mad
I've recently got my 72 Combat on the road after it was sleeping for 32 years in a garage, so I have an idea of where you may be going.
>>Danno wrote:
If you keep your Combat in stock spec, prepare to search out a source of 100+ octane leaded fuel. Insert a thicker headgasket and you may be able to run premium pump gas with a little lead substitute for the valves and seats.
Anyone you recommend getting this gasket from and any make in particular?<<
I also wanted to lower the compression from th Combat's 10 to 1 and I did it by getting an aluminum spacer plate from Old Britts that goes under the barrel.
Works fine for me however does mean lifting the barrel off pistons. I haven't seen a thicker head gasket out there but if it exists it would need to be metal not the isleted fiber ones Old Britts recommends. Purists will prefer the original copper ones.
If you get the bike you will want to consider adding the reed valve crankcase breather to minimize crankcase pressure and associated oil leaks. I use the SX650
one. Find a thread on the subject, lots of discussion.
I put the Pazon electronic ignition on mine. Works great and will work fine at lower voltages that would cause the Boyer to kickback.
I also swapped the twin Amals for a single 34mm VM Mikuni. This is a very common change. Simple operation, easy starting (big deal on this bike),
smooth running, helps low end torque and good fuel economy. The only way I see the twin Amals being worth keeping is cost (already there) or you are looking for that last 5% of power north of 6,000 RPM.
I put in a new Standard Cam in place of the Combat's 2S high performance one, which really requires running north of 4,000 whereas I really wanted more of a cruiser than a sprinter.
Replaced the transmission 19 tooth sprocket with a 21 toother for better cruising. Lost some excelleration but if I wanted to race stoplight to stoplight I'd get that new BMW S1000RR crotch rocket. 193HP !!!.
Parts for these bikes are available and don't tend to be expensive.
A lot of used and new parts and entire bikes are on EBay under Norton Commando. You have to careful but I've found some bargains there. My Mikuni with manifold, new in box for $125!!
Depending on where you are (country?). I've used a lot of sources and I find Old Britts here in the States has a great site worth browsing and excellent service. They have a whole bunch of tutorials on all kinds of operations including stripping and rebuilding transmission.
Getting the Shop Service Manual and Parts Manual will be essential going forward.
This bike requires you to get your hands dirty in order to save money and to really connect with it's soul.
But like others have said once you're hooked you're hooked!
Good Luck
Bob