- Oct 28, 2014
1972 Commando...10:1 pistons. How streetable would these be on city roads? the bike has a single 36MM mikuni. Problems?
Depends on your riding style. high cr is real noticeable at high rpm. with more cr you`ll get more forces to the cylinder head and the bolts. so....more likely to get the head blowing. Had my Dunstall pistons (10.5:1) (my moped is also a 1972..A combat at that time) trimmed for a less cr after some seasons. I like it going fast and doing many km on trips. But I am no racer pushing the bike constantly to the limit. Reliabelity is important for me. If you consider to change only the pistons ...only and just for higher cr...price-performance-ratio isn`t right. much work for little output. I wouldn`t do it...Although you are on the faster side of the riding style spectrum. if you want to go faster then I would rethink the whole operation....2 carburetors (maybe pumpers, FCrs, RS, Delorto)...maybe longer intake path...porting the head....decrease reciprocal weight...camshaft..... my 2 cents. But return to your question: of course it is streetable...1972 Commando...10:1 pistons. How streetable would these be on city roads? the bike has a single 36MM mikuni. Problems?
Other than the 36mm single Mikuni, is the rest of the engine to combat spec? 10:1 compression is as supplied for combats. I would not run a single 36mm it’s too large, but if it carburets OK for you then no problem.1972 Commando...10:1 pistons. How streetable would these be on city roads? the bike has a single 36MM mikuni. Problems?
Build for HER?? How to start it? Not much money ? Future rebuild cost? Keep it to the sensible / safe side of specs. is my suggestion.I do not know anything about the motor other than what I can see with the cylinders and head off. The owner does not have a lot of money to work with and NO previous experience with Nortons. I would like to build for her a Norton that does not give problems but the unknowns for me are a 36MM Mikuni on a 750 and 10:1 pistons. Ideally I would go to the 34 Mikuni and a set of 9:1 pistons. I should also check the bottom end and see if the suspect main bearing has been replaced. Anybody want to buy a pair of hardly used Powermax pistons?