Topic: cb650 mains and big ends bearings( crankcase and conrod bearings)and piston info

[spitfire79]

Hi guys,
So bought a complete basket case of a cb650sohc. Anyways, wont tell all my sad stories and money spent.

But I did have a problem finding the main bearings, the journals that go on the crankcase ? Could not find anything. Anyways, CB550 bearings fit perfetcly. So I am guessing the cb550 bearings would fit on the conrods for the pistons aswell.

A good source of honda workshop manuals and parts catalogs is the following website. Also has a good page for piston comparisons between the various models.

Piston info: https://4-stroke.net/library/honda-piston-size-chart.html
Workshop and parts: https://4-stroke.net/

Just thought I would share this..happy hunting for spares, and happy,safe hooligan miles on those Hondas

[fizzlebottom]

I've seen many times about people thinking the 550 bearings might fit the 650, given the complete unavailability of actual 650 bearings. But I don't recall ever seeing anyone positively report successful installation. Great news if that actually worked.

Did you purchase according to the bearing chart in the CB650 FSM or was there some translation from the 550 chart to 650 fitment?

[spitfire79]

Hi fizzlebottom.

I compared the bearing specs from the CB650 workshop manual and parts catalog, with the cb550f2 workshop manual and part catalog. Different part numbers, same dimensions.So yes, I did purchase according to cb550f2 bearing chart.

I have yet to fit them though. Going to have a wizzard assemble my crankcase,hopefully by month end. Will do another update then.

[bryanj]

Things i would check between shells

1. Are the locating notches in the same place

2. Are the holes for oil in the same plate

3  Do they both have grooves and are they positioned same and width same

[spitfire79]

Hi,
So the 550 F2 bearings I bought for my crankcase fit perfectly. Crankcase is back together.

Things i would check between shells

1. Are the locating notches in the same place - Yes it is

2. Are the holes for oil in the same plate - Yes it is

3  Do they both have grooves and are they positioned same and width same - Yes