Topic: Will 1974 CB550 transmission fit 1973 CB500

[Mickwc8]

I am a newbie to this group. I have read as many threads as I can find about parts interchangeability, but couldn’t find one the covers my question. I have a 1973 CB500 with transmission issues, and I also have a 1974 CB550 parts bike. Will the CB550 transmission fit on the CB500? Thanks much for any help.

[Deltarider]

Yes, it can. Here is one advertised: engine is CB500, transmission is CB550. https://www.motoroccasion.nl/motoren/honda-cb-500-m1323427.html

I have a 1973 CB500 with transmission issues

What's the nature of these issues?

[dave500]

the 550 bottom end is beefier than the 500 with a few improvements,the only parts that swaps is third gear.

[Deltarider]

Whatever. It can be done. That's what OP wanted to know.

[Mickwc8]

Thanks all!


Sent from my iPhone using Tapatalk

[dave500]

the 550 has a secondry oil pump for the transmission countershaft,the pick up and galleries don't exist in the 500 cases,the shift fork arrangement is entirely different with the 500 having all three on the drum,the 550 hangs two forks from a separate shaft,your best to use the entire 550 bottom end or complete motor.

[web]

I've seen that bike in person. What it has, is a 550 transmission and crankcase, with the 500 cylinder block, pistons and top end. Can't be sure which crankshaft they used because they are the same. So you CAN apparently put a whole 500 engine (at least all the moving bits) on a 550 transmission/crankcase.

But the only reason I can imagine to do such a thing would be if your 550 parts bike cylinders or top end are bad, otherwise just swap the whole thing.

What you can not do is put a 550 transmission in a 500 crankcase. You have to use the 550 case for reasons mentioned above.

[Deltarider]

Thanks all!

Still we'd like to know what the nature is of your transmission issues.

[Mickwc8]

The transmission is hard to shift, pops out of gear, and the clutch is slipping. Before I bought a new clutch and tore into the transmission, I was hoping there was some ability to use the 550 transmission. Sounds like that would be a lot of work. The top end of the 550 is damaged and not useable. Thanks again.


Sent from my iPhone using Tapatalk

[web]

You'd have to take the whole top end off the crankcases, but other than that, using a 500 engine on a 550 crankcase+transmission does seem straightforward. Undeniably a lot of work, but someone apparently did it on that one (I ended up buying it btw, partiallybecause I wanted its 550 crankcase+tranny for the tombstone bike...)

[bryanj]

People are making this difficult,

Basically NO tranmission parts ill transfer from 550 to 500 AND BEFORE SOMEBODY PIPES UP a very few parts will but not any big stuff.

500 parts from base gasket upwards will fit on 550 bottom end, no need to swap rods, just pistons and barrells even head, cam, camcover etc are identical 550 to 500 Honda even ise the same gaskets on both from base upwards!!!

[dave500]

third gear is the same.

[bryanj]

Not on the early 500  as they changed the tooth profile BUT you can fit as a running pair

[dave500]

the thrust flanges are also different,the shoulders on the shafts are different etc.

[Stev-o]

+1 no it cant.

There is only one guy in the whole SOHC world that claims the 500 doesnt have clutch/trans issues!
[even though Honda engineers totally changed the system after only 3 model years]

Get a 550 motor and slap it in!

[dave500]

the 500 clutch and transmission is a bit of a lemon if you ride the bike properly,if you baby it itll last longer.

[bryanj]

I will admit the 500 centre fork is not perfect, it came out of the 350 twin. As to the clutch, if you ignore chain maintainance it will snap the pushrod and the clutch will slip but i tried for 3 years tried to burn one out with many drag starts etc but never managed to total it and they do need best quality cables routed correctly.
The VERY eary 500 had a different neutral and gear detent which was soon modified as it was not good(according to hearsay----never saw one in UK) and 1 gear pair in the set was modified(tooth shape changed) and as the UK had 500 K1 from 72 to 77 i can honestly say warrantee work was rare and even older bikes were rarely stripped unless after an acccident

[dave500]

not just the centre fork the entire drum can end float even with the ferrule locting update,that lets all forks move creating sometimes a partial engagement and jump outs causing the dogs and slots to wear,every 500 trans ive seen has been rooted,usable but rooted.

[web]

500 parts from base gasket upwards will fit on 550 bottom end, no need to swap rods, just pistons and barrells even head, cam, camcover etc are identical 550 to 500 Honda even ise the same gaskets on both from base upwards!!!

That!

[web]

[even though Honda engineers totally changed the system after only 3 model years]

And then strangely continued to sell the lesser one everywhere but the US...

[dave500]

if ya hard on em they #$%* up,maybe elsewhere people rode em a little easier?i for one have thrashed the blood out of these things for years and ill only keep 550s,sure ill buy 500s but not to keep,just out of interest I highly vouch for the david silvers 550 over size piston kits and the 550 clutch kits.

[Deltarider]

+1 no it cant.
There is only one guy in the whole SOHC world that claims the 500 doesnt have clutch/trans issues!
[even though Honda engineers totally changed the system after only 3 model years]

No, they didn't, not on the CB500, they did modify however and in Europe CB500s have been succesfully sold up into early 1977.

[dave500]

successfully sold don't mean it wasn't promblematic?,Europe ended up with 500 top ends on 550 bottom ends from the factory,had to use up all the 500 barrels?or was it a road tax thing?either way the 500 transmission wasn't around.

[Deltarider]

successfully sold don't mean it wasn't promblematic?,Europe ended up with 500 top ends on 550 bottom ends from the factory,had to use up all the 500 barrels?or was it a road tax thing?either way the 500 transmission wasn't around.

Believe me, the combo 500/550 that Web has acquired, is a rarity. We're not talking the much later K3 models. That's a different story.
All I can contribute to a somewhat balanced overview, is that overhere the CB500 gearbox had a good reputation and was much praised for its smoothness. Personally I have never met or heard of one that had a problem. In both the socalled riders reports* that are in my archives, not one complaint has been filed that concerns the transmission, nor in any of the other articles in French, British, German, Italian and Dutch magazines that are in my collection. Mine has worked for 135.000 kms** flawlessly and still does. Clutch likewise. I can't rule out there have been problems with some early models over where you are.
What always strikes me, is that, in spite of the tens of thousands that have been sold ever since (here up to early 1977!), some will still continue to say: stay away from a CB500 transmission. Why? What knowledge do they have? It demonstrates how the internet works. Just repeat what you think is safe to repeat and you will at least be rewarded with 15 minutes of Andy Warhols fame in the world wide web. But misleading it is, as it is based on hearsay and always comes unquantified. If the issues the early model possibly had, had not been addressed by Honda, the company would not have survived. Having said that, this does not apply to you: you and Bryanj are always to the point and demonstrate first hand knowledge.
* The last one compiled of the experiences by 39 riders over a total of 2.338.462 kms, which equals 6 times around the world!
** In my archives there's also an article about a guy that at the time of the article had done 225.000 kms with just regular maintenance and still used his CB500 as a daily ride.

[dave500]

#$%*en hell?the 500 transmission is somewhat feeble compared to the updated 550 full stop,why would Honda pull all pins and update so much in the same basic platform retaining as much as the basic foundation as Honda could otherwise,man ill break a 500 transmission so easy,they cant hack the real world down under that's for sure!

[web]

Europe ended up with 500 top ends on 550 bottom ends from the factory,had to use up all the 500 barrels?

Nah that one linked up here is a homebrew one-off. They even wiped out the casing number partially, to "hide" the fact that it doesn't belong on the bike.
Someone probably did indeed break the 500 transmission on this bike, and proceeded to put his good 500 barrels on a 550 box.

Europe had the CB500 and CB550 sold beside each other for a while, with different transmissions. The 550 was not an outright successor like in the US.

So you could say they had to use up the 500 barrels as well as the transmissions :-) But apparently chose to do that in Europe only.

The CB500 continued to be sold (with small updates) until about 1977. Problematic or not - that I don't know, but last I heard, Deltariders' example was still working

Beside the red bike I also own a late model 500 transmission (i.e. one of the years where it was already discontinued in the US), but I have yet to find out if it still works.

[bryanj]

Main reason the 550 bottom end was reworked by Honda was because of the primary chain wearing into the oil gallery on the 500, which didnt show up for qhite a while. The K3 500 was because of a very big insurance cost jump for riders if bike was over 500cc.

As to werher us brits are nutters or not why did Yamaha have to do 3 exhaust mods on the 250/350 lc when it came here? Was OK in rest of world just us lot thrashed them so mercilessly they woyldnt stop leaking at the barrel.

Never mind Seasons Condiments to all and remeber when drinking at patries lean on the wall-----it hurts less when you slide down as against fall over!!!

[PeWe]

Plenty of knowledge here!

Every time I read about CB500/550 I get the thoughts that CB750 engine is much easier to work on. From totally taken apart to fully restored/ modified.

[Deltarider]

Web has been with us for only one and a half month and already now is the champion finding oddities.
Bryanj, the bike in your avatar, what color is it? The one Web owns, looks very close.
Pewe, you're the 750 guy. I know the CB750K3, K4 and K5 were not imported in The Netherlands. Was this the same for all of Europe?

[bryanj]

My bike is/was brown
UK 750 went from K2 direct to K6 i think along with F1 and 2 but no 3

[PeWe]

K3, K4, K5, K8 and F3 did not go this way.
K2 to 1975 still with K2 style gauges and rhino horn, then K6 followed by K7 1978.
K1 blinkers, rear fender and rear light was the style on all K2 and K6.
All K2 got the small bar on left side only to get bike on center stand.
K6 got the larger version all around rear part of the seat fastened into the upper shock bolts, handy for passenger to grab.

Details important to know before ordering parts from CMSNL that has charts for EU bikes, still US equipped.

[web]

I've always had a thing for oddballs. Just look at the people I hang out with