Topic: XS 650 Blown Motor

[Blackhorse]

I found a XS650 bike that is being parted out on craigslist. Owner sez the engine blew a hole in the piston. If I can pick it up cheap, I'd do a 277 degree rephase rebuild on it. What else besides the holed piston should I be worried about?

[HavocTurbo]

discolored rod.... crank.... spun bearings.... etc.

If you can get it cheap there are TONS of engine parts out there. I'd concentrate more on the rest of the bike's condition.

You can always get more engine pieces.... but some of the body parts for your particular year may be harder to come by.

[bryanj]

The first year had differnt pitch cam chain along with crank and cam that are unobtaiable now

[Blackhorse]

I should have mentioned that this bike was a '79. It is my understanding that 1976 - 79 were the best years.

[BeSeeingYou]

Like bryanj mentioned.  It will be easier to do this with a 447 engine.  Anything built from 1974 on.  The earlier 256 engines 1970-73 had some internal differences with  pistons and cam parts that are very hard to find.  1980 and newer had electronic ignition if you want that without the expense of aftermarket systems.

edit:  You got your post in right ahead of mine.  The carbs on the earlier models up to and including 1979 are more tunable and that may play into the "better years" idea.  Many think the 79 and older look better too.  The basic engines themselves are the same. Is this a Special or a Standard?  This would be the last year of the Standard and is a bit rare.

[Blackhorse]

Judging from the craigslist pic it looks like a standard. I just found out the frame has been sold. I'm looking at the motor for a bobber project. Anything else I should consider?

[BeSeeingYou]

If you want disc brakes on the rear look for a 78-9 Special not the Special II or Standard though almost all parts will mix and match.  The main difference in the carbs are the 79 and older are 38mm Mikuni and the newer 34mm and the newer ones have pressed in jets making them less tunable.  Being you are looking at a bobber most likely with pods the older carbs would be better 74-79.  The forks changed in 1977 to 35mm vs. the old 34mm and while you can get progressive springs for both  there are more upgrades available for the 35mm.  Forks and triple trees can be swapped so you could put 35mm forks on an older frame.  Brake calipers and MC's are also better from 77 and up.