Topic: Advice on CB650 -> CB550 Performance Upgrades, please...

[Ricky_Racer]

Sam, if this belongs in SOHC bikes, please move it for me...

I've got a couple '77-'78 CB550's and know a guy who's parting out a low-mileage '79 CB650.  I've arranged to get any requested engine parts from him, and so far this is my shopping list: The engine from the head on up (head, head bolts, valves, valve springs, cam and associated parts assembly, cam cover components).  Also, the oil pan and drain plug, pan bolts, oil pump with pickup, and primary chain tensioner assembly.

I don't think I need the carbs.

Have I missed any needed CB650 OEM parts to build an upgraded CB550 street performance motor?  CB550 racers... anything else I should get from the CB650 doner bike?  Mucho thanks!  RR

[Sam Green Racing]

See what happens Ted, I didn't see it untill tomorrow. 

Sam.

[Ricky_Racer]

Thanks, you blind ol' gentleman you!     RR

[Sam Green Racing]

Hey, not so much of the gentleman, you'll get me a bad name

Sam.

[Pinhead]

The CB650 has a larger combustion chamber and will yield very low compression with CB550 jugs/pistons.

I think Paulages crammed a CB650 head and jugs onto a CB550 but he went with a huge overbore and different pistons to get the CR back up.

Here's his CB650/550 Hybrid how-to thread.

[MRieck]

Thanks, you blind ol' gentleman you!     RR

You got the blind part right Ted.

[Ricky_Racer]

  Thanks, gentlemen.

It's been a while since I carefully read the Paulages 718 thread. Now I'm more intrigued than ever. I guess I'd better see about getting the complete CB650 motor (if it's inexpensive enough) so I can pick and choose combinations of parts from both the top and bottom end. I may even have some parts on-hand that I can throw into the mix (812 Yoshi pistons, 836 pistons, lots of CB750 liners, CB550 Mr. Turbo) that could really mix up the possible combinations.

When I got the two cheap ($270 and $250) complete late CB550's I had no interest in that model. Now the lightness and handling combined with the possibility of real horsepower has made them a lot more interesting.

Hmmm.. I wonder if the CB550 turbo kit would also fit the early CB650 engine?  Anybody wanna guess?

I guess we'll see where this all goes. Any continuing discussion/suggestion is appreciated. Thanks again. RR

[Sam Green Racing]

Blind ol gentleman that's half dead with a stonkin cold.
Coming from the heat over there to this god forsaken place was the pitts.
Hardly any sunshine, only good thing is they have lifted the hose pipe ban cos its not stopped raining for weeks.

Sam.

[Ricky_Racer]

Sorry to hear about your cold, Sam. Drink lots of Schnapps!

The weather here in San Diego is normally perfect, but we do get about three to four hot weeks where I live and they're happening now. 100 degrees and no fun! The only good thing is 27% humidity... but I'm still sweating my a$$ off! 

BTW, your weather may suck but I still love your country!  L8R.  RR

[Sam Green Racing]

The other thing that crossed my mind was the flight, you're couped up with a few hundred other people for hours on end all breathing the same air.
Me picking up a bug is a once a year thing just before Christmas but I have had a bad cold before after a flight.

Sam.

[CB500Four]

GD RR!

You also should take the clutch with its gearing.
And perhaps you could use the clutch cover in the future.
I have done some modifikations on a CB550 engine with some
CB650 parts. With some success.
Please take a look here:

http://forums.sohc4.net/index.php?topic=63938.0

At the end you should take the whole engine if it
isn´t too expensive. The carbs and the generator are not necessary.
Just my opinion.

Regards,

[bwaller]

Yes Sam couped up with that many other souls is more likely the cause of your grief...

I mentioned a while back a private jet is what you need, check with Honda maybe they'll cut you some slack being that you've been such a loyal guy. Then you can pick and choose your companions in flight!  

I hate to say this, but from someone who works outside everyday this has been a hot humid summer and I'm already halfbaked.  

Ricky 27% would be so bloody welcome I can't even tell you. But if I can suggest a good way to increase the fun factor of the middleweights besides finding extra power, taking fifty pounds off it helps wake em up.

[Sam Green Racing]

I hear ya Brent, It would look a bit strange wearing a face mask every time you  fly.

Sam.

[Ricky_Racer]

Take 50 pounds off?  Gawd, I'd love to!  I'd even settle for losing 20 pounds about now.  I wanna get back into my leathers by Christmas!     RR