Topic: 81' cb650 engine into a 76' cb550 Anyone done this? Is it an easy swap?

[markymark]

Hello all! I want to put an 81' cb650 motor into my 76' cb550 frame.  Has anyone done this.  If so please tell me the pros cons and how hard or easy it is.  I of course am hoping that it will be an easy swap.  But, do I have to worry about electrical(regulator and charging?).  Please let me know.  I want more power without having to go into my engine.  I love my 550 and it is such a cool little classic/cafe style bike. 

[scunny]

sorry, haven't done it but appently the cases are the same so the mounts might be the same as well. Only pitfall I can think of is the 650 motor might be taller, the 650's frame has a removable lower right hand rail to ease engine removal. try a search on paulages, he is comparing 550 and 650 bits at the moment

[cb650]

I know someone has done it.   Dont remember who and it might have been on the 650 site.




                                  Terry

[agiyo]

I did exactly that, early this year.  Fitting the engine in through the frame rails was a little tight, but I did it by myself.

Haven't gone thru the carbs yet, so haven't tried to make it run yet, but the engine looks fine sitting in there.

[paulages]

i imagine that using the stock airbox will be a problem, but i haven't compared the carb dimensions yet. using the entire 650 charging system shouldn't be hard to do at all. i have a complete wiring harness i'd let go for really cheap if you need any parts.

[markymark]

Sorry, but I made it work.  Ok so I took a 1980 CB650 motor and put it into my 76' cb550 bike.  I was wondering if it would work and from what I had read in the forums I went for it.  The motor slid right in.  Took a little jimmyin to get it in but worked just fine and bolted right up.  This was a junk yard motor so it smokes but still runs fast and hard.  Much more power than the 550.  Also I put a set of cb750 28mm carbs Kehin on too.  I also had these carbs on my 550 which did give the 550 quit a bit more power than the stock carbs.  Anyway,  i use pod filters that fit on the bike no problem.  The linkage from the 750 carbs do hit the tank a little but nothing a little bending didnt work out.  If I had a grinder(soon I'll get one) then I could have done a little grinding to the linkage and that would have worked fine without damaging integrity of the linkage.  I do miss not having a kick start but I think I will soon put a 650 head on the 550 engine I still have.  Looking forward to it.  Also I think I will put 750 pistons and sleeves and have the machine work done so that It will all fit in the 650.  Maybe I'm going to have a more problems than I will want doing this.  OH yeah forgot to mention that I also put the 650 wiring harness on my 550 frame no problems.  The 650 has a better charging system and electrical system than the 550 had.  The only hard part was connecting all of the control wires to the 650 harness.  I was able to find a great wiring diagram in the forum somewhere or on a google search for both the 550 and 650. 

I am very interested in finding someone who has used the OMNI Variable valves on one of these old bikes.  I would really like to try these or at least hear how they have worked on someones bike.  These valves sound like they would be awesome.  Anyone tried them yet?