Topic: Big Bore CB550 Engine Build

[Hannibal Smith]

I am going to post my rebuild and installation process for bumping up my 1974 CB550 to 592cc-

This is how it all started.

The Plan.

Kickstart only, totally reliable streetbike.

Bottom end will be stock, but inspected/rebuilt.
Top end will be punched out for 61mm pistons for a displacement increase to 592cc's
Cam will be replaced to better suit the displacement increase and provide more on the topend.
Stock valves and springs.

[Hannibal Smith]

Tore the mill down and started to inspect everything. Purchased a complete "Athena" gasket kit, and the remaining seals and o-rings to assemble the motor. The gasket kits are just that, all the seals and some o-rings must be purchased seperately.

I went to Bikebandit and via their schematics, just went down the line and ordered all the correct seals (crankshaft, kickstart shaft, clutch actuation arm etc.) and the oil pump o-rings.

Tearing it down is straightforward, just don't forget the 6mm fastener lurking beneath the oil pan that will effectively hold the case together!

[Hannibal Smith]

Bottom end inspection. PART 1

Caged bearings in the transmission. You can easily just replace them all, but if they are sound, there is no need to add to the landfill IMO. Every bearing except for the 22/63 on the rightside of the Primary shaft was 100% fine.

The 22/63 was serviceable, and could be re-used, but had just a wee bit more lateral play than what makes me happy so I merely went to a local bearing house and purchased a Koyo unit for $38.00 There was a slight benefit, the factory bearing had 6 balls and the Koyo had 7. The replacement bearing was non-shielded ("sealed") as is correct, but you can merely pry the seals off shielded bearings with a razor if need be.

The bearing pictured below was the only one that didn't feel brand new.

[moham]

from whence come your 61mm pistons?

what is the plan for cam, head, etc?

any plans for bottom-end work (crank, gears, etc)?

also, more pictures please...


 

[Hannibal Smith]

Bottom end inspection- PART 2

Transmission Main Shaft and Countershaft inspection.

My motor was virtually perfect internally, and everything looked brand new. I cleaned everything with paint thinner and a soft paintbrush and got it spotless.

IMPORTANT! Lift the shaft assemblies straight up (shaft parallel to ground) from the cases, or you run the risk of gears and caged bearings flying all about your shop. Lift carefully, and transfer everything onto some cardboard etc before pulling things off of the shaft. Make drawings/notes on your kickstart assembly too, you will thank me later.

[Hannibal Smith]

Bottom end inspection- PART 3

Primary chain.

My primary chain looked great, with virtually no visible wear. I inspected it carefully in bright sunlight and decided she was fine. If I had any bad vibes I would have swapped it, but the motor was so nice internally, and the bike was running super strong before I broke it down, so I had some prior knowledge about her condition. If she was a non-runner when I got it, I probably would have replaced the Primary chain to be perfectly honest.

My finger is pressing as hard as I can. and the primary deflects no more than a few millimeters. This motor was TIGHT!

IMPORTANT- A visual inspection should also be followed with a technical inspection (measurement etc.) but since my motor was so cherry, I made the choice to go ahead and reuse my primary.

[Hannibal Smith]

Bottom end inspection- PART 4

Crankshaft and Connecting Rod bearings-

Journals on the crank looked brand new, and the bearings looked virtually new. Kept everything in order, cleaned with thinner and checked with Plastigauge, everything checked out.

ConRod bearings checked out A-ok, and looked new.

Decided to keep the original bearings.

[Hannibal Smith]

Now for the fun stuff!

Prepped my cases for paint, and shot them with "Eastwood High Heat Engine Paint" with a conventional spraygun. Since I couldn't get the hardener in California (some banned ingredient), I had to fly to Ohio to shoot the paint at my Brother-in-laws house..........

[Hannibal Smith]

Looking good! I know for a fact that paint is going to look great in 15 years, I am too old to be rattlecanning stuff, that is for the kids.

[Hannibal Smith]

More to come, FEDEX just dropped my pistons off!

[Tretnine]

Also curious about your cam and piston choices.

[Hannibal Smith]

Bottom end buttoned up, I know she is sound in that department.
Purchased heavy duty studs from APE, great for peace of mind.

Made a new points cover just for cool points.

Made a starter block off plug with a built in castlenut just to be over the top.

[paulages]

Bottom end inspection- PART 3

Primary chain.

My primary chain looked great, with virtually no visible wear. I inspected it carefully in bright sunlight and decided she was fine. If I had any bad vibes I would have swapped it, but the motor was so nice internally, and the bike was running super strong before I broke it down, so I had some prior knowledge about her condition. If she was a non-runner when I got it, I probably would have replaced the Primary chain to be perfectly honest.

Those hyvo primary chains are known to stretch after fairly low miles. You'll want to measure its length against stock specs. I've found a chain stretched beyond specs in an engine with as little as 3000 miles on it.

[Hannibal Smith]

Bottom end inspection- PART 3

Primary chain.

My primary chain looked great, with virtually no visible wear. I inspected it carefully in bright sunlight and decided she was fine. If I had any bad vibes I would have swapped it, but the motor was so nice internally, and the bike was running super strong before I broke it down, so I had some prior knowledge about her condition. If she was a non-runner when I got it, I probably would have replaced the Primary chain to be perfectly honest.

Those hyvo primary chains are known to stretch after fairly low miles. You'll want to measure its length against stock specs. I've found a chain stretched beyond specs in an engine with as little as 3000 miles on it.

Maybe I should swap the primary chain at every oil change?

[jessezm]

Yeah just to be safe that's a good idea!

[bistromath]

Seriously though, there is no primary tensioner on the 550 so since you're doing all that work on the bottom end you might as well do it right so you don't have to go in there again. When the primary stretches it eventually chews a hole in the oil galley below.

[Hannibal Smith]

Seriously though, there is no primary tensioner on the 550 so since you're doing all that work on the bottom end you might as well do it right so you don't have to go in there again. When the primary stretches it eventually chews a hole in the oil galley below.

I understand where you are coming from.

If I had known these were 10,000 mile motors, I would have bought an AMF Harley or a late 60's Brit bike instead! I am just joking once again, but you have to keep this stuff in perspective.

Back when I started messing with motors and the like, boy I was paranoid, and swapped everything............until I began to understand them a little better. My Lotus Esprit motor was a "swap everything build" because with a Lotus, you have no choice, they start falling apart the next day. But a 1974 Honda CB550 that will make 60 horse if I am lucky, and can go 100,000 miles without a hitch? For every guy that lays awake at night worried about his timing chain with 1000 miles on it, there is some Hillbilly riding the piss out of his Honda chopper with Crisco in the crankcase for the last 30 years.

[paulages]

Seriously though, there is no primary tensioner on the 550 so since you're doing all that work on the bottom end you might as well do it right so you don't have to go in there again. When the primary stretches it eventually chews a hole in the oil galley below.

I understand where you are coming from.

If I had known these were 10,000 mile motors, I would have bought an AMF Harley or a late 60's Brit bike instead! I am just joking once again, but you have to keep this stuff in perspective.

Back when I started messing with motors and the like, boy I was paranoid, and swapped everything............until I began to understand them a little better. My Lotus Esprit motor was a "swap everything build" because with a Lotus, you have no choice, they start falling apart the next day. But a 1974 Honda CB550 that will make 60 horse if I am lucky, and can go 100,000 miles without a hitch? For every guy that lays awake at night worried about his timing chain with 1000 miles on it, there is some Hillbilly riding the piss out of his Honda chopper with Crisco in the crankcase for the last 30 years.

you're probably right and it'll be fine. i just chimed in in case anyone reads your write up as sort of a tutorial and thinks that "looking" at a primary chain constitutes proper inspection. best mod is to install a 650 tensioner.

[fmctm1sw]

best mod is to install a 650 tensioner.

Any refernce on where this is documented would be appreciated.  I have a 550 engine that will come apart later this summer...

[Hannibal Smith]

Seriously though, there is no primary tensioner on the 550 so since you're doing all that work on the bottom end you might as well do it right so you don't have to go in there again. When the primary stretches it eventually chews a hole in the oil galley below.

you're probably right and it'll be fine. i just chimed in in case anyone reads your write up as sort of a tutorial and thinks that "looking" at a primary chain constitutes proper inspection. best mod is to install a 650 tensioner.

You are absolutely correct, and I will edit that post to include this fact.

[bwaller]

Hannibal, good work. I have a 592 with a street WebCam and that engine is a great transformation over stock. I'm sure you'll enjoy it. I maintained the stock carbs though and it makes 51rwhp.

As paulages mentioned a CB650 primary chain tensioner is a nice addition. Once installed you can see how much slack there is even with a new chain.

[Tretnine]

I really like the idea of adding a tensioner. I'm sure Hannibal will maintain this bike better than most motors, so it's probably less of an issue. Is there a thread on the subject out there? I'd like to read more but search is failing me.

[bwaller]

CB500Four did this mod on his 500/650 race engine. I did the same thing on my own little race project (thanked him for the idea) It surely isn't necessary and does necessitate a hole through the cases.

Sorry for the de-rail Hannibal.

[Hannibal Smith]

No promises, but I might have something schemed up in regards to a tensioner.

[bryanj]

The 500 is worse than the 550 re holes in oil galleries, in fact several parts places in UK used to stock "spare" Honda cases just because of this, now they are rare to get, i had the last set from Dave Silver and even imported a set to UK from US.

Having said that it is easy to check wear with the sump of, which is on the service schedule for every 12,000, so it can be inspected and changed later.

If you had bought a late 60's Brit they needed boring every 10,000 anyway so you would have been no better off, as to Harley Fergusons----less said the better