Author Topic: 72 CB500 Simple Resto (Read 5022 times)

JustPassin'Thru · « **on:** February 12, 2011, 10:11:44 AM »

Hey everyone,

I spent some time on these forums over the last few months and finally found myself a bike. I found a 1972 cb500 from the original owner. He rode it until ~94' and parked it inside until i got my hands on it. I got some really simple plans for this bike. Clean it up as best i can, ride it.

Here are some pictures:

-Seems the starter button has rotted out
-Has a 4-1 exhaust
-Oil leak inbetween 2-3 cylinders on front
-blown fork seals
-dent in fender
-rust free tank(with beutiful chameleon sunfade)

Thanks for looking

mjstone · « **Reply #1 on:** February 12, 2011, 11:05:30 AM »

Nice find 5Hundo! Welcome to the Forum!

MJ

Goofaroo · « **Reply #2 on:** February 12, 2011, 11:41:59 AM »

That looks like a great bike for what you are wanting to do. I'm working on a 72 CB500 myself but yours looks to be in better condition. Cheers!

JBMorse · « **Reply #3 on:** February 12, 2011, 01:50:04 PM »

Looks like a great candidate for what you're planning. I love the way the candy color fades on the brown bikes! I would leave it like that if I were you.
I would clean it up well and run it, provided everything works. Have fun! The CB500 is a great bike.

MoMo · « **Reply #4 on:** February 12, 2011, 08:12:36 PM »

Agree, clean it up and ride. That looks like it should clean up well. Enjoy and welcome...Larry

Greggo · « **Reply #5 on:** February 13, 2011, 01:15:19 PM »

Here is probably one of the most helpful threads I've found on this forum, specifically about these bikes: http://forums.sohc4.net/index.php?topic=14273.0

Have Fun! That tank looks GREAT!!!

Oddjob · « **Reply #6 on:** February 13, 2011, 06:19:34 PM »

Might be the way the pics have come out but the tank looks like the olive green version not a faded Garnet Brown. I have a brand new green side panel lying around somewhere and it's the exact same colour that tank looks.

Nice find though, wish I'd found a tank with the chrome moulding still in place. I had a brand new set of chrome mouldings on my tank, lent the tank to the brother in law for his 500 whilst his was being worked on and when it came back he'd unclipped it all and lost it somewhere. Nice of him I thought.

JustPassin'Thru · « **Reply #7 on:** February 13, 2011, 06:36:38 PM »

Quote from: Oddjob on February 13, 2011, 06:19:34 PM

Might be the way the pics have come out but the tank looks like the olive green version not a faded Garnet Brown. I have a brand new green side panel lying around somewhere and it's the exact same colour that tank looks.

Nice find though, wish I'd found a tank with the chrome moulding still in place. I had a brand new set of chrome mouldings on my tank, lent the tank to the brother in law for his 500 whilst his was being worked on and when it came back he'd unclipped it all and lost it somewhere. Nice of him I thought.

The bottom half of the tank is brown. top is faded to green. right side cover is faded to green on the top but orange/brown on the sides

JustPassin'Thru · « **Reply #8 on:** March 13, 2011, 08:33:07 PM »

Been busy for a few weeks but got a good couple hours of work in and tore the head and jug off the bike. everything looks really good, still some hone marks on the walls. Might get away with just new gaskets.

The biggest problem i had was dealing with the damn valve cover bolts. These are definately being changed over to an allen type head. Here is a picture of it all dissassembled, nothing cleaned.

Looks as though some tranny seals have been leaking near the chain for awhile. or is this just from chain lube/road grime?

Head:

Cylinder linings(not very good quality pictures):

Can anyone identify this exhaust?

I also feel like that when i was trying to take off the chain, or release tension on the tensioner i was not as successful as i probably should have been. I tore it all down without a manual and think that i could have maybe done a few things in the wrong order and made things a little more difficult for me. Lesson learned and will obviously be using the manual for reassembly. All in all i have had a lot of fun with the few little things that i have done so far.

JustPassin'Thru · « **Reply #9 on:** March 13, 2011, 09:03:52 PM »

My bores are measuring out at 58.75mm which would be a 550 with a .25mm overbore. The numbers on the cases are a cb500. Are there other things that would have been modified in the head/valvetrain that are identifiable? Pistons are stamped with a 3.00 and Japan in the top of them.

Greggo · « **Reply #10 on:** March 15, 2011, 03:33:32 PM »

I can't give any info on your pistons, but it's very possible someone put a 550 top end on your 500's bottom end.

JustPassin'Thru · « **Reply #11 on:** March 16, 2011, 04:33:37 PM »

When did the 550's come out? Bike was sold in 74 with a 72 Vin. Cb500 bottom. I find it weird its a 550 with a overbore. Bike with 30k on its third set of pistons? Something is strange.

Only thing I can think of is if it was sold with 550 cylinders and pistons from the dealer. Anyways, going to use the cylinders and pistons the way they are. Hone and ring, then seal it up.

Greggo · « **Reply #12 on:** March 16, 2011, 06:15:38 PM »

Quote from: 5Hundo on March 16, 2011, 04:33:37 PM

When did the 550's come out? Bike was sold in 74 with a 72 Vin. Cb500 bottom. I find it weird its a 550 with a overbore. Bike with 30k on its third set of pistons? Something is strange.

Only thing I can think of is if it was sold with 550 cylinders and pistons from the dealer. Anyways, going to use the cylinders and pistons the way they are. Hone and ring, then seal it up.

You've definitely got a 500's bottom end, I can tell by the adjuster screw on your sprocket cover, and the shape of the clutch cover on the other side, so your engine number I assume starts with 'cb500EXXXXXXX'. What's the first few digits of the VIN on the steering neck? It's possible someone blew up the top end somehow and decided to replace it with the bigger displacement top end of the 550. Remember, a lot can be changed over 40 years that you wouldn't notice without opening her up like you've done.

JustPassin'Thru · « **Reply #13 on:** March 16, 2011, 10:07:02 PM »

1039075 on the frame
1039459 on the engine

fastbroshi · « **Reply #14 on:** March 17, 2011, 12:09:34 AM »

The stock 500 bore is 55 or 54.5mm, and the 550 was 58.5, so there's no way you've got 500 hardware up top.

mjstone · « **Reply #15 on:** March 17, 2011, 09:05:54 AM »

Could it have one of those big bore kits added? A 555 big bore or a 605?

MJ

JustPassin'Thru · « **Reply #16 on:** March 17, 2011, 12:31:35 PM »

Hmm. So it would be a 555 or a service overbore on a set of 550 liners/pistons. My trouble is i can't seem to find piston rings for a 550 +.25mm over. Would any 550 year work?

Ive also read numerous threads on this forum about the cylinders of 500's egging out and reducing power. Is this a common problem on 550's as well? or is this all sohc4?

fastbroshi · « **Reply #17 on:** March 17, 2011, 12:38:21 PM »

Quote from: 5Hundo on March 17, 2011, 12:31:35 PM

Hmm. So it would be a 555 or a service overbore on a set of 550 liners/pistons. My trouble is i can't seem to find piston rings for a 550 +.25mm over. Would any 550 year work?

Ive also read numerous threads on this forum about the cylinders of 500's egging out and reducing power. Is this a common problem on 550's as well? or is this all sohc4?

Answer to the first question is yes, as long as we're talking SOHC, or rather up until whenever they changed to the 550SC designation ('78?). I'm not sure about the second question. I thought that happened with all but the most modern motors.

JustPassin'Thru · « **Reply #18 on:** March 23, 2011, 09:52:54 PM »

I got a bunch of parts on the way and the most important ones have to be on back order. I need .25 over piston rings for a 550 58.75mm.

Greggo · « **Reply #19 on:** March 24, 2011, 08:41:56 AM »

Quote from: 5Hundo on March 23, 2011, 09:52:54 PM

I got a bunch of parts on the way and the most important ones have to be on back order. I need .25 over piston rings for a 550 58.75mm.

http://cgi.ebay.com/ebaymotors/New-Set-four-Honda-CB550K-CB550F-TEIKOKU-Ring-Kit-25-_W0QQcmdZViewItemQQhashZitem1c19c176cdQQitemZ120691193549QQptZMotorcyclesQ5fPartsQ5fAccessories

BOOM!

Oddjob · « **Reply #20 on:** April 05, 2011, 03:55:27 PM »

Bottom end is definetely a 500 as the 500 rotor cover had a plate with HONDA written on it, this was pegged onto the rotor casing, the 550 had the same design but the HONDA part was part of the rotor casing not a plate and there are 2 screws which hold the field coil visible from the outside, these were covered on the 500 by the Honda plate. Also the clutch push rod is visble, 550 doesn't have this system.

The cylinder barrels should be marked with either 500 or 550, IIRC it's on the front of the barrels, bottom edge and on the same side as the points. That should identify whether the barrels have been overbored from a 500 or have been fitted with a 550 set which has been rebored.

fastbroshi · « **Reply #21 on:** April 05, 2011, 07:24:14 PM »

Quote from: Oddjob on April 05, 2011, 03:55:27 PM

Bottom end is definetely a 500 as the 500 rotor cover had a plate with HONDA written on it, this was pegged onto the rotor casing, the 550 had the same design but the HONDA part was part of the rotor casing not a plate and there are 2 screws which hold the field coil visible from the outside, these were covered on the 500 by the Honda plate.

I think you may be incorrect on that plate on top of the rotor cover identifying the machine as a 500. I've got a spare 550 motor at the house that has this exact plate (missing).

Forgot to add, the 550 barrels will actually be marked 544cc, the 500s are possibly marked 498cc.

JustPassin'Thru · « **Reply #22 on:** April 06, 2011, 05:14:09 PM »

Not sure how i missed that oddjob, pretty obvious in my face 498cc stamped clearly on the cylinders. its a overbored 500, what exactly does this mean? were new sleeves pressed in for the 550 pistons? or can u really bore a 500 out that far and not have issues?

fastbroshi · « **Reply #23 on:** April 06, 2011, 05:26:49 PM »

No you wouldn't be able to bore out 500 barrels that far. Most likely they just took the barrels from the 550 like you guessed. Simple as that. FYI, you can get them out just by popping them in the oven for 15 minutes or so, and they drop right out. You'd probably damage something if you tried to press it.

Oddjob · « **Reply #24 on:** April 09, 2011, 01:40:47 PM »

May be incorrect here but I do recall Yoshimura selling a kit to bore the stock 500 barrels out to 605cc, the kit was just pistons, rings, pins etc but not liners. So maybe you can bore a stock 500 out that far. There certainly is a lot of extra meat on the barrel liners but whether it's doable I can't say for certain.

Weird about the rotor plate thing, in the UK the 550 got that plate machined into the rotor casing, however in the USA you got models we didn't. We never got the 550 in the UK with the 4 trumpet shaped exhaust pipes, we did get the 550 F1 and F2 with the 4 into 1 system and the 550K3 but the exhausts on the K3 weren't trumpet shaped.

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Author Topic: 72 CB500 Simple Resto (Read 5022 times)