Topic: 1973 CB550 First Build (Turbo Charged 600)

[Harris4627]

I recently acquired a nice little 550.  It is in overall good condition, but the engine was locked due to sitting...  I was able to break her free, but after lots of contemplation i have decided to do a rebuild, and go ahead and punch it up to a bigger cc.  Does anyone have recommendations for new, bigger pistons?  My goal is to bore it up to close to a 600cc, and run a turbo. I've been building and designing custom motorcycles for about 8 years now, but I've never done any engine mods.  So any help would be greatly appreciated!!

[Deltarider]

I seem to remember there was a turbo kit for the CB500... Can't remember the name though, anyway, you may find some inspiration here: http://forums.sohc4.net/index.php?topic=95323.0

[Harris4627]

Awesome! Thank you!! Also, the MFG decal says the bike was built 9/73 so would that make it a '74 model?

[Deltarider]

'Year' doesn't tell much. Write down your engine- and framenumber and compare it with the numbers listed in the first few pages of the various CB550 Parts Lists. They're all here: http://www.honda4fun.com/materiale-documentazione-tecnica/parts-list/parts-list-cb550

[Harris4627]

Here is a link to the piston kit that I'm considering...  Anyone have any experience with them> Good? Bad? Indifferent? https://www.japbikespares.com/honda-cb550k-sohc-74-78-600cc-forseti-big-bore-kit-61-5mm-piston-rings-gasket

[Scott S]

 If you're going turbo, I'd look at Wiseco or Cycles or Dynoman pistons.

[Yamahawk]

Here is a link to the piston kit that I'm considering...  Anyone have any experience with them> Good? Bad? Indifferent? https://www.japbikespares.com/honda-cb550k-sohc-74-78-600cc-forseti-big-bore-kit-61-5mm-piston-rings-gasket

For a cast piston set, those are pretty good. The manufacturer is reputable, and the compression ratio isn't excessive. When you run a turbo, you want a standard or slightly lower compression ratio as the turbo gives the extra compression. 9:1 ratio might be ok, but perhaps a thicker head or base gasket would be appropriate to get more like an 8.5:1 ratio. Not sure how much boost you plan to give that motor, but if you are looking at anything more than 7-8psi boost, get the forged pistons, and build it like a high-horsepower motor, rods, etc. ... remember, compression on a turbo motor isn't normally that high, due to the turbo. So don't go get a 12:1 set of forged pistons and then turbo it, or your engine will probably self-destruct if not built to the hilt...
Charlie