Topic: Need some advice from some of you Motor Gurus!!!!!

[Johnny-5]

Ok so I just picked up a 1973 Honda CB550 and its striped down pretty much and since Ill be sending some stuff to get repainted, etc. I figured I would mess with the motor a bit. Here's my plans and wanted some feed back......

Im going to have the Carbs, runners and cylinder head match ported and polished all the way through to the exhaust ports.

I was wondering since Im in there if I should get bigger valves, springs and cams? I was wondering if going with the CB750 components would make a difference or if its even worth while or if I should go with a different model bike???

As for the block Im going with the CB750 Pistons as I was told thats a good upgrade. Should I use just the pistons or will the rods work as well or is there even a difference between the CB550 and CB750 Rods???

Ill have the carbs rebuilt and rejetted of course. hmmm....I think thats about it really unless some of you can throw in more ideas? Oh and I'd prefer to stay with other Factory parts from other models from aftermarket as its easier and cheaper to come by and Im not really wanting to go all out. I mean even if you pump this motor out to its full potential its nothing compared to todays street bikes and if that was the case I would have gotten those instead. I just want to build a unique Cafe Racer with a little kick is all Im wanting.

Thanks in advanced!

[Duke McDukiedook]

How much $$$$ do you plan on dumping in this engine?

[Johnny-5]

Well hopefully a few hundred and is why Im wanting to stay away from aftermarket. Im going to be saving majority of the money for the suspension upgrades, paint, modifications of the frame things like that.

How much $$$$ do you plan on dumping in this engine?

[Duke McDukiedook]

If you only have a few hundred to spend don't crack the engine if it works well.

To do the amount of things you want to do will take more than a few hundred greenbacks.

I don't think much at all is compatible in the engine from the 750 to 550.

[Johnny-5]

Well the bikes been sitting for years and things have been left open so to be safe Im going to crack the motor open. Either way my friends doing all the porting and polishing for me so thats going to be cheap. Ill probably get new rings, seals, gaskets, etc. That alone is going to cost me a few hundred. Im not calculating that into the few hundred I want to spend on upgrades.

Getting the bore size needed for the 750 pistons is not an issue as I have a shop for that as well. Just wondering if there is anything I should do to the valve train?

Hopefully that clears things up a bit. Sorry should have been more specific.

If you only have a few hundred to spend don't crack the engine if it works well.

To do the amount of things you want to do will take more than a few hundred greenbacks.

I don't think much at all is compatible in the engine from the 750 to 550.

[OldSchool_IsCool]

Since its an early 550, you may first want to make sure the rocker shafts aren't knackered.  Search the forum for "550 rocker shaft wear" for tips on diagnosis and repair options.

Porting will give you a pony or two, a cam shaft from a 650 will give you a few more.  Stay away from pods and rejetting.  More trouble then its worth.

Search the forum also for "Hondaman Ignition Module" and "Higgins Fuse Box" upgrades for performance & reliability.

[mlinder]

A few hundred won't get you much more than a port and polish on 1 cylinder.

I could be wrong, but going to 750 pistons requires:

Machining of the jugs to accept cb750 liners, the cb750 liners themselves, and possibly machining of the pistons to work properly with the deck height and valves.

The gasket kit alone is about 100 bucks.

Leave the engine alone, and get your suspension upgrades, tires, and bit's you'll need to make the bike turn and stop well.

The only thing I might consider doing for "a few hundred bucks" on one of these is the 650 cam swap, and some different carbs.

/edit:

OK, I see you've qualified the porting and piston size bit.
So, on top of that, yes, a 650 cam (or hotter) and a little bigger carbs (gs750's and gs550's slide piston carbs appear to be an almost direct bolt on, with the 550 carbs needing a relocation of the throttle butterfly.)

[OldSchool_IsCool]

MLinder makes some good points.  You don't want to beef up the engine if the brakes and suspension can't control it.  That is prolly the smart place to put ur $$.  Koni shocks, progressive springs both fore and aft, braided brake lines with rebuilt master cylinder and caliper.  Dual disk... not so much.

The single most important component to a competitive bike is the part between the handlebars and the seat.  Make sure you can handle what you got before you build a monster!

Those Honda engineers knew what they were doing 30+ years ago.  Don't spend too much time or $$ trying to out think them.  If it is modern sportbike performance you want, then you bought the wrong bike.

[mlinder]

The suspension and brakes on these, stock, when they were new, were nothing to write home about (my old 71 and 72 r75/5's with drum brakes stopped better), though they were 'adequate'. You wouldn't believe how much faster you can go on one of these old bikes with new avons, some progressive suspension all around, stainless steel brake hoses, new steeringhead bearings, and new swingarm bushings done properly (like Hondaman does). Getting rid of a little weight on the bike, and maybe something like cartridge emulators for the forks and a fork brace... These things will make these old bikes ride better than 3 times the money thrown at the engine. Once you have those things done, enjoy your ride, and save up for an absurd transmorgification like Paulages did on his 650. Better than 70 rwhp....
But do the other stuff first. You'll enjoy the bike more, you'll be able to go faster, and you'll be a lot safer.

[Johnny-5]

Hey good point Ill definetly keep that in mind. Hell I may actually take the head off tonight so Ill do more research on that!

As for pods and rejetting is it really that problematic? Another thing Ill have to keep in mind.

Since its an early 550, you may first want to make sure the rocker shafts aren't knackered.  Search the forum for "550 rocker shaft wear" for tips on diagnosis and repair options.

Porting will give you a pony or two, a cam shaft from a 650 will give you a few more.  Stay away from pods and rejetting.  More trouble then its worth.

Search the forum also for "Hondaman Ignition Module" and "Higgins Fuse Box" upgrades for performance & reliability.

[Johnny-5]

Sorry I meant to say the 650's. Sorry Im getting all my numbers out of wacked today. So I was told to go with the 650 pistons and with some machining work those will work good.

A few hundred won't get you much more than a port and polish on 1 cylinder.

I could be wrong, but going to 750 pistons requires:

Machining of the jugs to accept cb750 liners, the cb750 liners themselves, and possibly machining of the pistons to work properly with the deck height and valves.

The gasket kit alone is about 100 bucks.

Leave the engine alone, and get your suspension upgrades, tires, and bit's you'll need to make the bike turn and stop well.

The only thing I might consider doing for "a few hundred bucks" on one of these is the 650 cam swap, and some different carbs.

/edit:

OK, I see you've qualified the porting and piston size bit.
So, on top of that, yes, a 650 cam (or hotter) and a little bigger carbs (gs750's and gs550's slide piston carbs appear to be an almost direct bolt on, with the 550 carbs needing a relocation of the throttle butterfly.)

[Johnny-5]

Thats where most of my money is going to be going to. Im actually researching the R6 front end conversion and thinking of going with a dual disk braking up front and converting the rear braking to a disk as well. Also going to be mocking up a steering dampner on this bike as well for extra stability control.

MLinder makes some good points.  You don't want to beef up the engine if the brakes and suspension can't control it.  That is prolly the smart place to put ur $$.  Koni shocks, progressive springs both fore and aft, braided brake lines with rebuilt master cylinder and caliper.  Dual disk... not so much.

The single most important component to a competitive bike is the part between the handlebars and the seat.  Make sure you can handle what you got before you build a monster!

Those Honda engineers knew what they were doing 30+ years ago.  Don't spend too much time or $$ trying to out think them.  If it is modern sportbike performance you want, then you bought the wrong bike.

[Johnny-5]

You and everyone else who posted are right but since this is going to be a project and not going to be done anytime soon anyways I figured I work my way with what I got for now. The bike is still incomplete so even if I wanted to enjoy the ride right now I wouldnt be able too. Thus the reason why Im wanting to build the motor for when the time is right and I can get the other parts needed to fully complete the bike.

The suspension and brakes on these, stock, when they were new, were nothing to write home about (my old 71 and 72 r75/5's with drum brakes stopped better), though they were 'adequate'. You wouldn't believe how much faster you can go on one of these old bikes with new avons, some progressive suspension all around, stainless steel brake hoses, new steeringhead bearings, and new swingarm bushings done properly (like Hondaman does). Getting rid of a little weight on the bike, and maybe something like cartridge emulators for the forks and a fork brace... These things will make these old bikes ride better than 3 times the money thrown at the engine. Once you have those things done, enjoy your ride, and save up for an absurd transmorgification like Paulages did on his 650. Better than 70 rwhp....
But do the other stuff first. You'll enjoy the bike more, you'll be able to go faster, and you'll be a lot safer.

[mlinder]

Sorry I meant to say the 650's. Sorry Im getting all my numbers out of wacked today. So I was told to go with the 650 pistons and with some machining work those will work good.

A few hundred won't get you much more than a port and polish on 1 cylinder.

I could be wrong, but going to 750 pistons requires:

Machining of the jugs to accept cb750 liners, the cb750 liners themselves, and possibly machining of the pistons to work properly with the deck height and valves.

The gasket kit alone is about 100 bucks.

Leave the engine alone, and get your suspension upgrades, tires, and bit's you'll need to make the bike turn and stop well.

The only thing I might consider doing for "a few hundred bucks" on one of these is the 650 cam swap, and some different carbs.

/edit:

OK, I see you've qualified the porting and piston size bit.
So, on top of that, yes, a 650 cam (or hotter) and a little bigger carbs (gs750's and gs550's slide piston carbs appear to be an almost direct bolt on, with the 550 carbs needing a relocation of the throttle butterfly.)

650 pistons won't really work in the 550 jugs and head. Not enough room up there in the 550 head for 'em. You need to use the 650 head if you want to run the 650 pistons, I think.

[Johnny-5]

Could someone clarify on this??? I was told all I needed was the pistons and boring of the cylinder and its in. If its more of a headache Ill opt not to do this route.

Sorry I meant to say the 650's. Sorry Im getting all my numbers out of wacked today. So I was told to go with the 650 pistons and with some machining work those will work good.

A few hundred won't get you much more than a port and polish on 1 cylinder.

I could be wrong, but going to 750 pistons requires:

Machining of the jugs to accept cb750 liners, the cb750 liners themselves, and possibly machining of the pistons to work properly with the deck height and valves.

The gasket kit alone is about 100 bucks.

Leave the engine alone, and get your suspension upgrades, tires, and bit's you'll need to make the bike turn and stop well.

The only thing I might consider doing for "a few hundred bucks" on one of these is the 650 cam swap, and some different carbs.

/edit:

OK, I see you've qualified the porting and piston size bit.
So, on top of that, yes, a 650 cam (or hotter) and a little bigger carbs (gs750's and gs550's slide piston carbs appear to be an almost direct bolt on, with the 550 carbs needing a relocation of the throttle butterfly.)

650 pistons won't really work in the 550 jugs and head. Not enough room up there in the 550 head for 'em. You need to use the 650 head if you want to run the 650 pistons, I think.

[mlinder]

PM Paulages and ask him, I think he's got the measurements on them. Again, pretty sure I'm correct on this, though I've been wrong before.

[Johnny-5]

Ok you were right Paulages just confirmed they will not fit! Guess Ill scratch that!

PM Paulages and ask him, I think he's got the measurements on them. Again, pretty sure I'm correct on this, though I've been wrong before.

[Johnny-5]

Here's another question for you guys.....

I just recently came up on a full CB650 Motor and want to know what I can use from the engine? Could anyone tell me a list of things I could use from it?

Cams I know I can use with minor modifications. Will the Rods work? Cylinder Head?

Thanks,
Johnny

[mlinder]

Johnny, there's a lot from teh 650 you can use in the 550.
You need to go read Paulages build thread. Lemme find the link.....

http://forums.sohc4.net/index.php?topic=40414.0

You could do all this without boring out to the 750 pistons, just the 650 pistons.

[Johnny-5]

SWEET!!! Thanks again! You rock!

Johnny, there's a lot from teh 650 you can use in the 550.
You need to go read Paulages build thread. Lemme find the link.....

http://forums.sohc4.net/index.php?topic=40414.0

You could do all this without boring out to the 750 pistons, just the 650 pistons.

[Johnny5]

The new rings for my 750 cost $160. Stuff aint cheap.

[mlinder]

Why do we have a Johnny5 and a Johnny-5?

Are you two related? Or perhaps you are the SAME PERSON. Oh, the duplicitousness!

[Johnny5]

Why do we have a Johnny5 and a Johnny-5?

Are you two related? Or perhaps you are the SAME PERSON. Oh, the duplicitousness!

I've also seen a Johnny-Five too.



It's a cool name that everyone wants.

[mlinder]

Why do we have a Johnny5 and a Johnny-5?

Are you two related? Or perhaps you are the SAME PERSON. Oh, the duplicitousness!

I've also seen a Johnny-Five too.



It's a cool name that everyone wants.

Not I, Sir, not I.

[Johnny-5]

The new rings for my 750 cost $160. Stuff ain't cheap.

Yea I'm finally realizing the costs on things!! lol Oh well nothing I can do about it now.