Author Topic: Will 1974 CB550 transmission fit 1973 CB500  (Read 2682 times)

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Offline Mickwc8

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Will 1974 CB550 transmission fit 1973 CB500
« on: December 09, 2019, 10:16:49 AM »
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.

Offline Deltarider

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #1 on: December 09, 2019, 12:23:32 PM »
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?
« Last Edit: December 09, 2019, 12:27:28 PM by Deltarider »
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Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #2 on: December 09, 2019, 01:39:58 PM »
the 550 bottom end is beefier than the 500 with a few improvements,the only parts that swaps is third gear.

Offline Deltarider

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #3 on: December 09, 2019, 02:30:53 PM »
Whatever. It can be done. That's what OP wanted to know.
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Offline Mickwc8

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #4 on: December 09, 2019, 03:39:18 PM »
Thanks all!


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Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #5 on: December 09, 2019, 04:00:09 PM »
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.
« Last Edit: December 09, 2019, 04:02:18 PM by dave500 »

Offline web

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #6 on: December 09, 2019, 11:37:29 PM »
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.

Offline Deltarider

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #7 on: December 11, 2019, 06:59:46 AM »
Thanks all!
Still we'd like to know what the nature is of your transmission issues.
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Offline Mickwc8

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #8 on: December 12, 2019, 10:35:50 AM »
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.


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Offline web

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #9 on: December 12, 2019, 12:46:04 PM »
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...)

Offline bryanj

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #10 on: December 12, 2019, 01:21:08 PM »
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!!!
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #11 on: December 12, 2019, 01:33:08 PM »
third gear is the same.

Offline bryanj

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #12 on: December 12, 2019, 03:58:59 PM »
Not on the early 500  as they changed the tooth profile BUT you can fit as a running pair
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #13 on: December 12, 2019, 04:05:50 PM »
the thrust flanges are also different,the shoulders on the shafts are different etc.

Offline Stev-o

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #14 on: December 12, 2019, 04:35:32 PM »
+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!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #15 on: December 12, 2019, 05:10:16 PM »
the 500 clutch and transmission is a bit of a lemon if you ride the bike properly,if you baby it itll last longer.

Offline bryanj

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #16 on: December 12, 2019, 05:27:07 PM »
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
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #17 on: December 12, 2019, 06:43:00 PM »
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.

Offline web

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #18 on: December 12, 2019, 10:24:35 PM »
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!

Offline web

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #19 on: December 12, 2019, 10:27:30 PM »
[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...

Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #20 on: December 13, 2019, 12:25:24 AM »
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.

Offline Deltarider

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #21 on: December 13, 2019, 01:31:43 AM »
+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.
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Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #22 on: December 13, 2019, 01:44:50 AM »
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.

Offline Deltarider

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #23 on: December 13, 2019, 02:58:52 AM »
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.
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Offline dave500

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Re: Will 1974 CB550 transmission fit 1973 CB500
« Reply #24 on: December 13, 2019, 03:18:58 AM »
#$%*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!