Topic: CB550F with CBX550 engine, any experience?

[zoolander]

Hello petrolheads,

I'm new to the forum but luckily not to Honda CB's ;o)

I know its sacrilege but the other day a neighbour rocks up and gives me a CBX550 '82 DOHC free of charge.
My mate happens to have ridden his CB550 caféracer hard all over Europe since the last 20 years.

Then the idea came to swap engines (CB550 engine has had it's best time) and to properly rebuild the bike.

Is there anyone who has experience in this build?
We are in the process of making new engine supports to fit the CBX engine because the normal ones don't match.
So far we have lined up the sprockets, found the correct height but need to move a bit more forward. Only problem now is to fit the valve cover but we'll manage.

We're also reinforcing the frame with gussets and extra tubing since we're fitting a GSXR fork and brakes etc.... Any specific advice would be welcome too.

I know it will not be the most authentic bike out there but we've ragged up enough miles over the last decade or two to be ready for a change.
The bike(s) need to be able to do an occasional trackday too.

Please have a look at the pics. You can see the original bike and work in progress...

Greetz from the belgies

[CBGhia]

What kind of tank is that?  Is it going to fit over that engine?  It looks like a smaller tank will be needed.

[turboguzzi]

i think youll get much more response if you posted in the projects forum rather than the hi-performance one..... boys over there love that kind of crazy stuff

good luck, even if i believe you'd have spent much less time by refreshing the older motor.... just by dropping in a 600 kit you'd have gotten a nice performance improvement

[bwaller]

Plus a CB550 punched to 592 with head, cam & carbs will out perform that CBX. It'll be thirstier, and not as smooth but who wants smooth fuel efficiency?   

[SOHC4 Cafe Racer Fan]

Plus a CB550 punched to 592 with head, cam & carbs will out perform that CBX. It'll be thirstier, and not as smooth but who wants smooth fuel efficiency? 

+1!

[Retro Rocket]

Plus a CB550 punched to 592 with head, cam & carbs will out perform that CBX. It'll be thirstier, and not as smooth but who wants smooth fuel efficiency? 

 I'm not sure what models you guys got overseas, but here in Australia, the cbx 550 was a popular model with between 65 and 70 HP, with little work they can get  more HP, especially port work, for free, its far cheaper than kitting up the old sohc engine and will be much smoother in its power delivery, make sure you keep the oil at its top mark, both the CBX550 and CBX750 need to have their oil level checked regularly. The 550 CBX engine will be considerably lighter than the CB engine.  I had the CBX 750, I love these engines ...

[bwaller]

Mick nobody said anything about hotting up the CBX!

[Retro Rocket]

Mick nobody said anything about hotting up the CBX!

Price comparison Brent... Comparing stock to stock, Its a win for the CBX...   The 6 speed box is a bonus too...

[SOHC4 Cafe Racer Fan]

Mick,

Will the CBX550 directly bolt up to a 550 frame?

[Retro Rocket]

Mick,

Will the CBX550 directly bolt up to a 550 frame?

I doubt it Don.... The CBX550 had a nice little monoshock frame too, they handled very well, I never liked the enclosed brakes on them though, but like everything, that can be fixed... ...

[turboguzzi]

mick, dont tell me that you take brochure claimed 65 horsepower for real.... some years ago a brit mag took an excellent condition cbx550 and it gave 53.... those were the days, Kawaski claimed around 60 for the gpz550, cycle mag dyno gave more like 50.... pumped up numbers where the name of the game back then. BTW, 550 where claimed 50 hp but more like 38 on the dyno. been checking these numbers because tought at the time of building a 600 racer out of a gpz.

not saying that a 16 valve 550 cant be stronger than a 8 valve 550 (quite the opposite, as per my examples). all i am saying is that instead of investing all that time and effort into making this transplant work, our belgian dude could have a nice & reliable 48-50 hp sohc....
shame that the guy is not even checking his 1st thread answers ....

[SOHC4 Cafe Racer Fan]

Equally important is losing weight on the bike by ditching unnecessary parts or swapping to lighter ones. Approx 1 hp for every pound lost.


-- OOPS: I meant 1 hp for every 7 pounds lost.

[bwaller]

Now Don, if it was that easy to gain juice we could add wings & fly! I know you meant 7-10 lbs per pony. One guy in one of my race classes has a CBX550 and it's not a rocket buy I know what you mean Mick, I was just raising Cain!

BX

[zoolander]

Hi guys,

thanks a lot for the first opinions  I know I've not been checking the first trhreads but I was working on my mancave all weekend in which the bikes house ;o)
I understand the mixed emotions but the engine is already in the frame by now. We are now in the process of fabricating the engine mounts. Once thats done the frame gets the necessary reinforcements and it's going for a powder coat.
I believe that the 16 valve engine can perform well provided that the carburettors are tuned well and we have just the guy for that around the corner.
Do you actually know someone who has made such a transformer yet?
Also tips on reinforcement, in particular with the CBX engine, are welcome too...

I'll post some pictures of the work in progress.

As for the tank I don't know which type it is but indeed it's not fitting anymore. Trying a dunstall next week...

Cheers to the belgian beers 

[Retro Rocket]

mick, dont tell me that you take brochure claimed 65 horsepower for real.... some years ago a brit mag took an excellent condition cbx550 and it gave 53.... those were the days, Kawaski claimed around 60 for the gpz550, cycle mag dyno gave more like 50.... pumped up numbers where the name of the game back then. BTW, 550 where claimed 50 hp but more like 38 on the dyno. been checking these numbers because tought at the time of building a 600 racer out of a gpz.

not saying that a 16 valve 550 cant be stronger than a 8 valve 550 (quite the opposite, as per my examples). all i am saying is that instead of investing all that time and effort into making this transplant work, our belgian dude could have a nice & reliable 48-50 hp sohc....
shame that the guy is not even checking his 1st thread answers ....

I get what you are saying TG, if they say 60hp, I just use that as a crank figure, not rear wheel. He would have had to spend money to get the 48-50 hp 550 though TG, thats the point here, he got the CBX engine for free, clean up the inlet ports, throw a pipe on it and he'll already be around 60 reliable HP, maybe more, the cbx engine is another engine that responds well to any work on the ports..

Zoolander, If i wanted the look of the old 550 and the engine from the CBX, I would have used both the cbx550 engine and frame,  it wouldn't take much at all to make the stock cb550 tank seat and side covers fit on the CBX frame...

[zoolander]

hi guys,
Thanks for the info again...
Using the complete CBX frame is an option too although it has a single shock in the rear (not as retro) and I do not know if the head bearings are the same either so we can install allball bearings for the GSXR fork. Side covers we definately want to get rid off. All electrics will be renewed and put underneath the saddle.
Anyway, we are in the process now and continuing to work on this idea. Indeed a reliable 60HP is the aim for this bike. That in combination of trimming as much weight as possible and to have proper stiff frame and good suspension/brakes should result in a fast bike...I hope...
It needs to become a nice looking retro bike but foremost it needs to ride well too.

- Anyone has experience with welding a cross between the 2 pipes that go down behind the engine? It should stiffen the frame significantly as it sits close to  the swing arm hinges.
- Also do we put gussets in all three corners where the electrics used to be?
- Also the head we will reinforce by welding 2 tubes left and right and 2 gussets too.

Any tips remain welcome and I'll keep you posted with pics on the progress.

Good tip to put this thread under "projects" but I guess that's too late now?

Greetz,

Roeland

[turboguzzi]

you could easily turn the CBX550 frame to twin shocks.... just weld mounts, it's been done before (in general)
 and yes, in the project thread you'll get much more appreciation,
if you use the CBX frame then that new project anyway....
if it's a street ride, i wouldnt put much energy into frame bracing, better get good shocks, fork, brakes

[SOHC4 Cafe Racer Fan]

The monoshock CBX550 IS retro, just not AS retro as the twin-shock CB550.  I could not see why, if you had a CBX550 WITH the monoshock, you would want to regress the technology of the bike to a twin shock design.  If the basis of using the engine was to improve performance, why would you ditch the inherent improvement to the suspension?  Looks alone are not so important.
Just my $0.02 rant.  You can flush it if you like!!

[Retro Rocket]

The monoshock CBX550 IS retro, just not AS retro as the twin-shock CB550.  I could not see why, if you had a CBX550 WITH the monoshock, you would want to regress the technology of the bike to a twin shock design.  If the basis of using the engine was to improve performance, why would you ditch the inherent improvement to the suspension?  Looks alone are not so important.
Just my $0.02 rant.  You can flush it if you like!!

If you've seen the CBX frame Don, it wouldn't take much to run the CB550 tank, it should go straight on, and some small mods to the seat mounts and you have a CBX550 that looks like a CB550, Ive seen the later model 750 honda with the cbx750 engine done as a 750/4 and it looked stock at first glance, it would fool many people...   I'll post a pic if I have one...

[Retro Rocket]

Here you go....

[SOHC4 Cafe Racer Fan]

Here you go....

Not bad, at all. 

[zoolander]

OK guys,

I guess it all makes sense what you are saying...
I'll set up the CBX with the CB tank and seat etc...Then talk to my buddy what he thinks of it...In the end we'll have 2 bikes 
I do need to weld a downpipe back into the CBX frame coz I borrowed it for the CB 

i want to put some reinforcements as we are using our bikes on the track every now and then. We also race classic bikes occasionally (BMW) and like it when a bike is tight and direct...
I keep you posted.

[zoolander]

Hello,

We've stripped the CBX frame and tried tank and seat etc...All these parts parts basically fit. Rear wheel should fit too if we mill the rear swing arm out by 2mm (shaft is thicker on CB M16 vs. M18) but we don't like the look of the swing arm. It has an over engineered linkage system and the frame reaches too far backwards...
The steering stem is also 5mm higher whereby the GSXR Fork might not fit.
Anyway, we decided to stick with the original plan and will use the CB550 frame and CBX engine. We have made the gussets and engine supports now. Next thing is weld the gussets and extra engine supports for the engine on and make a tray for the electrics and we're ready for powder coating the frame. 
We also tried the Dunstall tank (yellow one) but it's too narrow in comparison with the engine so we're modifying the fuel tap on the green tank and use that one. To be continued...

[SOHC4 Cafe Racer Fan]

Do the CBX motor mounts match up to the mount points on the CB550 frame or do you need to make modifications?

[zoolander]

No, not 1 point matches up. Lining up the chain is possible (Y direction) but  generally you need to put the engine aprox. 25mm backwards (X+ direction) into the frame and make all new engine mounts (4 and 5 mm plate steel). We also decided to make every mount out of 3 fixation points to add strength. Most of the M8 holes we drilled to M10 size for the same reason. In the height (Z direction) we were able to lower the crankcase to the same height but the engine is slightly higher than the CB550 so we might have to chop off a bit of frame on the top. But thats actually good coz then we can add 2 tubes from the steering stem to the main beam to add some rigidity. Also you need to put the engine in without the valve cover and once it is in, you put it on. I'll post some pics to clarify all...