Author Topic: CB550 - CB650 interchangability (Read 19425 times)

kayaker43 · « **Reply #50 on:** July 13, 2006, 08:38:50 AM »

Whoa,.. I finally compared valve sizes. The 650 valves are huge compared to the 550. An extra 4mm intake and 3mm exh makes a big difference on these tiny valves. Ports are way bigger too. better. Anyone know what the 750 valve sizes are for comparison??

Thinking back to when tuners would go to great expense to machine the heads for a 1mm valve increase, and extensive porting for tiny flow improvements. This head is radically better than what yoshimura's best 550 race heads could have been!

Now to find out the best/biggest pistons to use. I only have one picture of CB750 pistons and it looked like the valve pockets were offset, the 650 has them directly opposite eachother. I have 550 a cylinder with 750 liners and was hoping to use some 750 big bore pistons. If that doesn't work, anyone know the biggest safe bore for the 650 liners? I missed out on the 605 kits on ebay, anyone know where to find one?

Ibsen · « **Reply #51 on:** July 13, 2006, 09:35:53 AM »

I don't know where the limit goes for tyhe 650 liners, but if you intend to use the 650 cylinders I think you will need a longer single row camchain as well, since the longer stroke on the 650 makes the cylinder block higher? And I don't know if the 550 crankcase have got the correct groove for the bottom end of 650 camchain tensioner, or if the 650 and 550 tensiner can be interchanged.

kayaker43 · « **Reply #52 on:** July 13, 2006, 09:49:00 AM »

Yeah,.. I wondered if the 5.2mm stroke could be absorbed by trimming the piston skirts, or whether the cyl was taller. I hear the tensioner notches are different, but could be dealt with easily.

That's why someone needs to get these engines side by side and do an autopsy to document this stuff. I may have a lead on a 650 motor for this purpose in a couple weeks?

Ibsen · « **Reply #53 on:** July 13, 2006, 10:02:07 AM »

Quote from: kayaker43 on July 13, 2006, 09:49:00 AM

That's why someone needs to get these engines side by side and do an autopsy to document this stuff.

I agree 100%. And it would be very interesting to read the results.

I don't know why, but it seems like the 650 is somewhat the unwanted stepchild amongst the SOHC Hondas, whilst a magazine like Classic Motorcycle Mechanichs regarded it as highly underrated, and maybe with the best SOCH engine Honda built.

bill440cars · « **Reply #54 on:** July 13, 2006, 10:29:00 AM »

That's why someone needs to get these engines side by side and do an autopsy to document this stuff.

Quote

I agree 100%. And it would be very interesting to read the results.

I don't know why, but it seems like the 650 is somewhat the unwanted stepchild amongst the SOHC Hondas, whilst a magazine like Classic Motorcycle Mechanichs regarded it as highly underrated, and maybe with the best SOCH engine Honda built.

Quote

I too, would like to see some documentation. It could come out from under that "Black Sheep" cover and become quite a sought after item. Bring it on. Later on, Bill

cb650 · « **Reply #55 on:** July 13, 2006, 08:30:52 PM »

I have junker 650 for someone or will accept a junker 550 to compare to another good 650. I think I have one or two around. Really want to investigate the kickstart BS.

Terry

kayaker43 · « **Reply #56 on:** July 13, 2006, 08:43:42 PM »

Terry,.. I'll pay for a good 650 motor if you have one. Where are you located?

E-mail me at: buildstuff@comcast.net

Doug

cb650 · « **Reply #57 on:** July 13, 2006, 08:50:21 PM »

I'm in Denver CO. Dont want to get rid of the good motor. Dont know how "good" it is anyway. Ran but have no idea on the history. Swapped it for one I did a top end on.

Terry

DammitDan · « **Reply #58 on:** July 13, 2006, 08:57:43 PM »

I also have a trashed '82 CB650std motor that's currently in pieces in my parents basement (although I never could split the cases...), and one installed on the '82 CB650sc parts bike that's just missing the top end, although it still has the block and pistons installed on it though.

It was sitting for a while but it hand cranks easily. Maybe someone else can get some use out of it?

82CB650SC · « **Reply #59 on:** July 14, 2006, 06:45:19 AM »

Hey DammitDan the 650 valves are back on ebay from DK trader
http://cgi.ebay.com/ebaymotors/NEW-INTAKE-VALVES-FOR-HONDA-CB650-79-82_W0QQitemZ270007753841QQihZ017QQcategoryZ35595QQrdZ1QQcmdZViewItem

kayaker43 · « **Reply #60 on:** July 14, 2006, 06:50:49 AM »

Well both of you guys are a little too far from detroit for us to compare parts. I have a lead on an 82 engine with 7000 miles. I hope I can get it?

My Dennis Kirk valves came in and two of the exhausts were different. I called and they are sending more, so I know they also have exhaust valves in stock. Can't beat $1.99 each

DammitDan · « **Reply #61 on:** July 14, 2006, 04:35:42 PM »

Quote from: 82CB650SC on July 14, 2006, 06:45:19 AM

Hey DammitDan the 650 valves are back on ebay from DK trader
http://cgi.ebay.com/ebaymotors/NEW-INTAKE-VALVES-FOR-HONDA-CB650-79-82_W0QQitemZ270007753841QQihZ017QQcategoryZ35595QQrdZ1QQcmdZViewItem

Yeah, I actually grabbed the last of the exhausts on Wednesday. Found 'em in my daily CB650 ebay search

When I finally get the new head from this other guy, I'll be all set for starting to rebuild the top end.

jt · « **Reply #62 on:** July 17, 2006, 10:50:49 AM »

Quote from: kayaker43 on July 12, 2006, 10:16:11 AM

JT... I just welded some short tubes to a flange and bolted them up to the head,.. don't have them anymore.

I've got lots of yosh parts too,.. TT100 cams, super rods, 5 and 6 speed close ratio trans kits. That TT100 cam is tuned for high rpm power. I thought it was great until I mated it with the yosh racing header with short primary tubes, then it REALLY came alive. You need a short tube header for the best match, otherwise use a milder cam? The power didn't hit till 8-9000, then it pulled like a two stroke. Not very good for the street, but with a close ratio trans it was perfect for the track.

I sure wish I had a 650 head back then...

kayaker, Thanks for they reply, the Action Fours header I have has the short primary length tubes, so it should rev.

JT

Pinhead · « **Reply #63 on:** August 16, 2006, 11:46:11 PM »

Any updates? Has anyone been able to compare the two motors??

kayaker43 · « **Reply #64 on:** August 17, 2006, 08:49:15 AM »

I was looking for bargain motors but two new cb650 motors in crates just sold on ebay, I got one of them. Now I don't need to teardown and rebuild it so I can't compare internal parts. I may still pick up a parts motor so I can do this??

Lots of 650 engines on ebay, but no one will ship.

Pinhead · « **Reply #65 on:** August 17, 2006, 10:43:02 AM »

1979 CB650 motor - BIN $45
Add $20 to crate
email for shipping

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4606101000&sspagename=STRK%3AMEWA%3AIT

Glenn Stauffer · « **Reply #66 on:** August 18, 2006, 10:45:10 AM »

The CB650/550 and CB550-650 interchangeability threads have been merged. I will add information gleaned from this thread to the website soon.

cb650 · « **Reply #67 on:** August 18, 2006, 12:56:29 PM »

Damn and I wanted to start another

.
I have this junker if anyone want parts for comparing. The cam chain guide was busted. Took some stuff of it but its going to scrap yard soon.

Terry

Pinhead · « **Reply #68 on:** August 18, 2006, 02:20:01 PM »

I don't suppose you have another good rotor, would you?

How much for the motor + shipping to 66212?

cb650 · « **Reply #69 on:** August 18, 2006, 03:03:32 PM »

I'll look but I doubt it. Stater is still there.

Terry

Pinhead · « **Reply #70 on:** August 22, 2006, 11:49:32 AM »

Getting back on topic, maybe we should change the title to "Interchanging aftermarket parts" so we can try to fit overbored 750 pistons (836cc kit) into a 650... Change to the 750's piston liners? Imagine: 10.25 compression, 836cc, with the 650's truly hemispherical head (no valve shrouding). Less weight, probably better power. That's why I'd like to CAFE a 650. If it would work...

dusterdude · « **Reply #71 on:** August 22, 2006, 01:32:41 PM »

go for it,i would love to hear about it.

kayaker43 · « **Reply #72 on:** August 22, 2006, 04:41:27 PM »

A 650 has less stroke than a 750 so an 836 kit would give something less than 836? I came a cross a cb500 roadracer that had 65 mm pistons from a KZ650 running in 750 liners with a 650 head and he said it was 700cc with a CB500 crank!!

I wonder what the maximum displacement could be with a 650 crank and 65mm pistons. I heard rumors that 750cc is possible?? when I get some time, I need to gather the numbers and crunch them to come up with a displacement chart. At least now I know 65mm bore is doable.

bill440cars · « **Reply #73 on:** August 22, 2006, 05:59:15 PM »

Quote from: kayaker43 on August 22, 2006, 04:41:27 PM

A 650 has less stroke than a 750 so an 836 kit would give something less than 836? I came a cross a cb500 roadracer that had 65 mm pistons from a KZ650 running in 750 liners with a 650 head and he said it was 700cc with a CB500 crank!!

I wonder what the maximum displacement could be with a 650 crank and 65mm pistons. I heard rumors that 750cc is possible?? when I get some time, I need to gather the numbers and crunch them to come up with a displacement chart. At least now I know 65mm bore is doable.

Say, I'd be interested in that displacement chart, if you don't mind. I'd like to know what the most displacement you could get and still have it hidden inside what would appear to be a 500/550 motor without spending 2 arms & 3 legs.
Later on, Bill

Pinhead · « **Reply #74 on:** August 22, 2006, 06:01:30 PM »

Quote from: dusterdude on August 22, 2006, 01:32:41 PM

go for it,i would love to hear about it.

I'd be all over it if I had more than $0.27 in my bank account.

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Author Topic: CB550 - CB650 interchangability (Read 19425 times)

Ibsen

Ibsen