Author Topic: CB500 big bore? (Read 6352 times)

jwcsdc · « **on:** August 01, 2009, 05:52:13 PM »

I posted before and looks like I was wrong. The bike we got my wife that was suppose to be a 550 is really a 500. The problem I have now is that the pistons are 63mm, lot bigger than stock. Im just wondering what I have? Does anyone else know of or have something simular? Thanks

Bill/BentON Racing · « **Reply #1 on:** August 01, 2009, 07:44:03 PM »

What pistons are 63mm? a 590cc 550 is 61mm.Bill

jwcsdc · « **Reply #2 on:** August 01, 2009, 08:05:09 PM »

Yep, 63. I micked them. This is my first honda build and Im just lost to be honest. On top of that its my wifes bike and she is ready to ride. They are honda pistons, markings on the bottom are CB810 and HA-64 even says honda on them

bucky katt · « **Reply #3 on:** August 01, 2009, 08:10:04 PM »

those sound like 810 cc pistons for a cb750, want to sell them?

Bill/BentON Racing · « **Reply #4 on:** August 01, 2009, 08:12:09 PM »

What size were CB650 pistons?

Bill/BentON Racing · « **Reply #5 on:** August 01, 2009, 08:22:53 PM »

Boss man he said 63mm,not no 550 four!,These pistons came out of bike?engine serial# please?,this will tell us what bike and year.Bill

bwaller · « **Reply #6 on:** August 01, 2009, 08:35:32 PM »

A 630cc CB500. Don't think I ever saw this done.

650 pistons have too tall a dome for a 500 combustion chamber.

Beans · « **Reply #7 on:** August 01, 2009, 08:41:19 PM »

If you can man take lots of pics of the motor and post them. it might help the people that know give u a better answer. plus it would be cool to see.

paulages · « **Reply #8 on:** August 01, 2009, 10:41:46 PM »

811cc cb650 pistons are 64mm. i don't know what 63mm pistons would be from, but you certainly don't have stock liners if your measurement is correct.

jwcsdc · « **Reply #9 on:** August 01, 2009, 10:51:53 PM »

Im scratching my head trust me, Ill take a few pics tomorrow and post them. The numbers on the case are CB500. Yes they did come out of the bike, cant say I want to sell them. Bike ran great even with problems. It would scat with my 100 pound wife on it.

jwcsdc · « **Reply #10 on:** August 01, 2009, 10:54:12 PM »

Oh, rest of the numbers. CB500E-2014542 Can someone tell me more about it?

bryanj · « **Reply #11 on:** August 02, 2009, 12:43:52 AM »

1972 cb 500 K1 motor with a very big bore kit---must have had different liners and top case opened out and pistons from some other Honda, possibly a 350 twin, machined to fit.

With the 500 primary chain wear problems i would fit a new one before it eats into the oil galleries

Bill/BentON Racing · « **Reply #12 on:** August 02, 2009, 06:10:35 AM »

More info ,pics please any #s on pistons,stock head??,cam?,Carbs?jets?,You sure have one big bore CB500,has to have had work done to run those pistons. Bill

bwaller · « **Reply #13 on:** August 02, 2009, 06:53:27 AM »

Are these flat-top pistons?

With different sleeves, 350 twin pistons may be possible, but the biggest issue would be reducing the crown enough (or increasing combustion chamber enough) to make those work.

I had these pistons in my 750 when racing and the CR was up there even with the bigger 750 chamber.

Bill/BentON Racing · « **Reply #14 on:** August 02, 2009, 06:59:01 AM »

Brent ,I wondered the same thing 18-1 comp? Just kidding but we got to know more? Bill

mlinder · « **Reply #15 on:** August 02, 2009, 07:54:54 AM »

Um, yeah.. that would put you at 631cc's.
Really need to take some pictures of everything and post em up.
CB350 twin is 64mm bore, so the pistons aren't from a 350.
63mm is, what, the 810 kit for a 750?

jwcsdc · « **Reply #16 on:** August 02, 2009, 07:56:23 AM »

The head is at the shop along with the cylinders/jug whatever the proper term is. Ill stop by and get the head number monday and now I see I have something special Ill pic the cylinders up tues till I figure out what to do. Like I said, we got the bike not knowing anything about it other than it ran. The guy at the bike shop is looking for 550 pistons, guess that wont do my any good,lol Here is a pic from the day we got it.

jwcsdc · « **Reply #17 on:** August 02, 2009, 08:07:23 AM »

Here are a few more

jwcsdc · « **Reply #18 on:** August 02, 2009, 08:09:58 AM »

Inside of my pistons say CB810

mlinder · « **Reply #19 on:** August 02, 2009, 08:26:17 AM »

Quote from: jwcsdc on August 02, 2009, 08:09:58 AM

Inside of my pistons say CB810

Yep, those are 810 pistons for a cb750.

paulages · « **Reply #20 on:** August 02, 2009, 10:40:25 AM »

Quote from: mlinder on August 02, 2009, 08:26:17 AM

Quote from: jwcsdc on August 02, 2009, 08:09:58 AM
Inside of my pistons say CB810

Yep, those are 810 pistons for a cb750.

811 pistons are 64mm.

paulages · « **Reply #21 on:** August 02, 2009, 10:43:09 AM »

Quote from: jwcsdc on August 02, 2009, 08:09:58 AM

Inside of my pistons say CB810

when you get the cylinders back, let's see a shot of the top. i had to custom make liners from a cb750 to get 64mm pistons into a 650 block, which is still the same spacing as the 500. also, look and make sure the cylinders say "498cc" on it. this would be the original clyinders for the motor.

mlinder · « **Reply #22 on:** August 02, 2009, 11:03:56 AM »

Quote from: paulages on August 02, 2009, 10:40:25 AM

Quote from: mlinder on August 02, 2009, 08:26:17 AM
Quote from: jwcsdc on August 02, 2009, 08:09:58 AM
Inside of my pistons say CB810

Yep, those are 810 pistons for a cb750.

811 pistons are 64mm.

64 were listed as the '812' kit, usually, far as I know, Paul.
Do believe 63 were typically denoted as the 810 kit, even though it came to less than 800cc's. Much like th e'605' kit for the 550's, which is, what, 590?

bwaller · « **Reply #23 on:** August 02, 2009, 12:47:18 PM »

Pistons appear flat top, the plot thickens. Stock looking 22mm carbs to boot.

turboguzzi · « **Reply #24 on:** August 02, 2009, 01:08:47 PM »

mixing up stuff here, but the CB500R works racer from another thread had 64mm for a 650 capcity, surely not flat top

J, seeing that you are coming from Big Twins and have no honda four experience, make sure to download/ read the manual. pulling these fours appart is much easier that putting them back together and there are lots of points were you can screw up easily: fitting the pistons back, bending valves with the rocker cover, etc.

why did you take it appart in the first place?

TG

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Author Topic: CB500 big bore? (Read 6352 times)

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