Topic: cb550 piston and ring size question

[d3buttz]

so i am doing a rebuild and i have a question.  if i need to bore my cylinders due to its (possible) wear limit being over-i will need bigger rings.  the .25 or .50 lets say.  thats not 500 thousanths(no way 1/2 an inch), its 50 thousanths right, or even 5 thousanths-.50 millimeters?? also do i need to get a .25 or .50 larger replacement pistons, or can i use my same pistons with the new bigger rings (if they are not beyond the limit)?

[FunJimmy]

Those measurments are fractions of a mm. The stock 550 has a bore of 58.5mm and a 0.5mm over bore is a 59mm piston.
0.5mm = approx 20 thou of an inch. New larger bore pistons are required too.

[bryanj]

The oversizes are in metric I.E. millimeters (mm) and you need pistons and rings, not forgetting circlips

[d3buttz]

geeze, rings are 70$ to start with.......and pistons would be around 200, an ebay 605cc kit is looking like a beneficial option if im possibly looking at machine time.

[hymodyne]

NO!!! don't drink the HA 605 overbore kit koolaid!! Stick with OEM.

-from a man who knows...

hym

[d3buttz]

what was the issiue?

[FunJimmy]

what was the issiue?

They use poor quality one-piece oil rings.

[jcorrill]

I know that this is an old forum, but i figured id still post and ask.  Does anyone know if this would be a decent upgrade, or if its just crap.  I would probably get a different head gasket (honda one)?

http://www.ebay.com/itm/Honda-CB550F-CB550K-600cc-Bigbore-Piston-Kits-with-Head-Gasket-CB550FBB-/161127970617?pt=Motorcycles_Parts_Accessories&hash=item2583f9b739&vxp=mtr#ht_1123wt_916


Thanks for the help

[bryanj]

That seller has a good reputation but you will have to use the gasket that comes with the kit as Honda don't make one

[Spiderbath]

Hey jcorrill, did you get the big bore kit? I'm thinking of doing the same thing but I'm curious about rejetting the carbs.