1978 CB550 Pieces/Parts Hellride

Here’s another attempt at an engine for this bike. I want a kickstart, so I’m going to see what I can make of this CB500 engine I bought for $50
I can only see three other bikes in that photo so yeah it's about time you started making life difficult for yourself
 
Was never able to get the 650 to run full power. Replaced the clutch, ran several ignitions, never figured it out. I literally hate not having a kickstarter and I would much rather run a smaller battery, so the plan I have come up with is to run a 550 bottom end which has a kick start, 650 pistons, bored 550 cylinders for 650 pistons, and a 650 head and cam with a 550 cam sprocket.
 
Was never able to get the 650 to run full power. Replaced the clutch, ran several ignitions, never figured it out. I literally hate not having a kickstarter and I would much rather run a smaller battery, so the plan I have come up with is to run a 550 bottom end which has a kick start, 650 pistons, bored 550 cylinders for 650 pistons, and a 650 head and cam with a 550 cam sprocket.
I'm not familiar with the 650 engine. Is the head a bolt on or will it require machine work?
 
That’s interesting Irk, i’ve taken my 550 out to 61.5mm=600cc

never seen a sohc 650 let alone worked on one !
 
That’s interesting Irk, i’ve taken my 550 out to 61.5mm=600cc

never seen a sohc 650 let alone worked on one !
It's a common swap to machine the crown of CB750 pistons and machine down the skirts to get your size piston on the CB550. Not sure you have to do that anymore, as you have done. I assume you've heard of or read the "Gentleman's Express" article which refers to that process. CrazyPJ has a few posts out there about this, as well. The CB650 piston is 59.8mm.

I'm not familiar with the 650 engine. Is the head a bolt on or will it require machine work?
Honda used the same tooling to build the 650 engines, so everything is pretty much the same as far as castings. The 650 head is the better head, since it has shorter runners and it's ported. Honda put the last of their SOHC tech genius into that head. The rocker covers are different, but they match up to by bolt pattern. People tend to like the look of the 550 engine better, but I like the rubber gasket design of the 650 covers.

The sleeves on the 650 have a larger OD, so I can't run them in the 550 case without boring the case. It's easier to machine the 550 jugs to match the 650 pistons. The 650 pistons have a crown, where the 550 pistons are flat top. The 650 also has better chamber design. Dimensionally, the 650 matches the 550 piston in every other way. The clutch is the same on both the 650 and the 550, so I like the 550 bottom end to get me a kick starter. I may pull the starter from this engine altogether.
 
Excited to see this come together. That was my last plan I had for my 550 Cafe, to run a hybrid 650/550 motor. I have 3 650 top ends sitting in a tote in my shed and plenty of 550 parts if you need anything.
 
Got my jugs mailed to Ohio to the house of @Hurco550 where he’ll do me a solid and deliver them to Mototech. I started taking the bike apart when a CB360 tank I bought for the Floating Donuts build got delivered. I had to go and test the tank on this build, which unfortunately looks pretty awesome. Now I have a problem.

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My $0.02 worth??? I like the other one a little better. Part of the really unique look of that one was that tank line.

EDIT: Yup, just looked again. The line created by that long n low tank, the seat, and rear fender is what really makes that bike unique and special. Don't mess w/ success!
 
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Going a little backwards here, but I’ve decided I want a kick start bike and the OG 550 bottom end. So we’re doing a 550 bottom end, 550 cylinders bored for 650 pistons and a 650 head. Should be somewhere around 568cc.

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Not a lot of detail shots, but I’m super proud of the direction this bike has taken. I know I’ve posted in the cycle kart thread about the Motorsports Engineering classes I started at my school. Well, in late January, I started a club for the 8th graders. The high school kids get course credit, but that wasn’t an option for the middle school. I did start the 8th graders on the 378 build, but then I decided to bring this 550 to the school and see if they’d be interested in working on it. Needless to say, these kids became obsessed. Now, I’ve got these kids coming in during study hall, lunch and after school every day to work on this bike. The club was only supposed to meet Wednesdays during what we call M period. This is an hour period at the end of every day where assemblies happen, clubs meet, advisory meets, stuff like that.
We got the motor mostly together with the 650 pistons and valve train, Murray’s carb kit and a Dyna ignition. Monday, we’ll get the 650 clutch installed.
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The next generation getting their hands dirty, what a gift to pass down. Nice work man, doing it right
 
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