Author Topic: WILL A CB500 BIG BORE KIT 605CC WORK ON A CB550??? (Read 10025 times)

randy5307 · « **on:** March 22, 2010, 01:16:10 PM »

I HAVE FOUND A 605CC BIG BORE KIT AND THE LISTING SAYS ITS FOR A CB500 BUT I THOUGHT THE 605CC KITS WERE FOR THE CB550.IT COMES WITH SLEEVES PISTONS RINGS AND PINS W/CLIPS. WILL THIS KIT WORK FOR MY BIKE? BELOW IS THE LINK TO THE KIT INFO IF NEED TO VERIFY..

http://cgi.ebay.com/ebaymotors/Honda-CB500-Four-BIG-BORE-605cc-Performance-Rebuild-Kit_W0QQitemZ200451683999QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item2eabd9f69f

TwoTired · « **Reply #1 on:** March 22, 2010, 01:41:41 PM »

Yes, it will "work" on the 550
It actually changes the displacement to 572 cc. Given the piston is actually the reported 60mm. 61mm pistons yield 592 cc

You don't need to replace the cylinder sleeves on the 550 for 60mm pistons. Just bore the sleeves that are there to 60mm.
The one piece oil rings have been problematic regarding oil consumption. Most replace them with 3 piece rings to fix that. The pistons must be re-grooved (machined) to achieve that.

randy5307 · « **Reply #2 on:** March 22, 2010, 01:52:49 PM »

where would i find a set of rings that have the three piece oil ring?

randy5307 · « **Reply #3 on:** March 22, 2010, 01:56:06 PM »

is the kit worth the money ($400) plus machining for the power gain i will get? or should i search for a diff set of pistons that will yield better power for the money?

moham · « **Reply #4 on:** March 22, 2010, 02:03:31 PM »

Incidentally, 60mm pistons from an 85 Kawasaki gpz will work, as well (with a little machining, of course). Then you can use the stock Kawasaki 3 piece oil rings...put it with a 650 cam and you've got a decent little upgrade.

bistromath · « **Reply #5 on:** March 22, 2010, 02:11:20 PM »

moham, please give details on the machining of the GPZ pistons. i wasn't aware there was anything out there with compatible wristpin dia and deck height.

randy5307 · « **Reply #6 on:** March 22, 2010, 02:14:30 PM »

yes i agree info as to what machining is needed if i was to use them pistons. and i also already ordered a 650 cam and tach gear.. so all i need is a set of pistons and rings and i think i will have a decent power gain i hope

TwoTired · « **Reply #7 on:** March 22, 2010, 02:25:31 PM »

Quote from: randy5307 on March 22, 2010, 01:52:49 PM

where would i find a set of rings that have the three piece oil ring?

If they were 61mm pistons, you would just use the std. 750 oil rings.
If they are really 60mm, I'm not sure without a search for them.

randy5307 · « **Reply #8 on:** March 22, 2010, 02:27:55 PM »

ok where could i find a set of 61mm pistons then?? i am trying to research all my options here..

mlinder · « **Reply #9 on:** March 22, 2010, 02:47:47 PM »

Quote from: randy5307 on March 22, 2010, 02:27:55 PM

ok where could i find a set of 61mm pistons then?? i am trying to research all my options here..

Stock cb750 pistons are 61mm...

randy5307 · « **Reply #10 on:** March 22, 2010, 02:55:11 PM »

ok if i go with stock cb750 pistons in my cb550 will i need to do any modifications other then boring out the sleeves? what bout the pins will they fit my stock rods? and the piston height. will my valves clear?

moham · « **Reply #11 on:** March 22, 2010, 02:57:04 PM »

Quote from: bistromath on March 22, 2010, 02:11:20 PM

moham, please give details on the machining of the GPZ pistons. i wasn't aware there was anything out there with compatible wristpin dia and deck height.

The gpz is dohc and the pistons have 4 valve reliefs, you still need two for the sohc. Soos is the one that did the pockets on my pistons (as well as provide said pistons). Wrist pin diameter is same at 15mm* (I think 15mm is right, it's certainly not 23mm) and the deck height was nearly identical. One thing I was worried about was losing CR on machining the pistons for valve reliefs but after cc'ing the chambers and all that my motor came in at 9.0:1, same as stock. I wonder if one was really precise with the valve reliefs, etc if you could use a thinner gasket to make up a little more CR, but I don't know, especially with running a hotter cam. As someone else stated, stock liners can be bored to 60mm no problem. With regard to gasket, Cometic has part nos. for both 60mm and 61mm for 550.

My 550 motor has the 60mm gpz pistons, 650 cam, stage 2 ported head (Mrieck), new valve springs and some other little things...

hope this helps.

Randy, stock 750 pistons are 61mm and are the inspiration for the "Gentleman's Express" motor mods (among other mods) that a lot of people talk about on here with regard to the 550.

EDITED: Wrist Pin Diameter...

TwoTired · « **Reply #12 on:** March 22, 2010, 03:07:48 PM »

750 std pistons are 61mm. But, they need to be machined for the 550, too.

Have you searched this site yet for info. I know all this has been discussed before. And there was a "Gentleman's Express" magazine article that went into gory detail about such an upgrade. I can't find that right now, though.

http://forums.sohc4.net/index.php?topic=44678.msg466170#msg466170

moham · « **Reply #13 on:** March 22, 2010, 03:38:09 PM »

Here's the link to the original thread/article...

http://forums.sohc4.net/index.php?topic=20601.0

bistromath · « **Reply #14 on:** March 22, 2010, 05:10:48 PM »

I'm far from an engine guru, but after modeling the Gentleman's Express piston modifications in SolidWorks and calculating the compression height and volume, I got 12.5:1 compression. There's way too much meat on those pistons to use in a 550 without radical modification, and radically modifying the pistons is likely to reduce the top ring land thickness to a really scary point. While it has been much discussed, I've been unable to find anyone who has actually done this modification. If anyone pops up with clarifications, that would be nice.

mlinder · « **Reply #15 on:** March 22, 2010, 05:14:14 PM »

There have been one or two, and Paulages did 750 (actually, I think he did 812) pistons in his 650 top end.

Also, Mike Rieck did the top end for a gentlemens express fairly recently, he may be able to tell you what he saw or noticed or did.

moham · « **Reply #16 on:** March 22, 2010, 05:30:54 PM »

Strongperf has been working this mod as well, I believe he was/is to the point of machining the pistons...he has a project thread going.

bistromath · « **Reply #17 on:** March 22, 2010, 05:34:19 PM »

We've been in touch -- I'm waiting for him to get the pistons installed and compression checked so we can see if I'm a dope or not.

moham · « **Reply #18 on:** March 22, 2010, 05:53:02 PM »

There was someone else on this board who had done the 750 modded pistons at one point (in history)...it might have been crazypj? I can't remember, but one of those guys chimed in awhile back when I was getting started...And if Mike has just done one, I would imagine he would be as good a guy as any to talk to...good luck to ya. I'm interested to see what you find out and how these other projects develop.

randy5307 · « **Reply #19 on:** March 22, 2010, 06:05:38 PM »

well i been online all day exhausting all my options and just when i was gonna give in to machining a set of 750 pistons i run across a set of 61mm big bore kit made by HENRY ABE.. i am awaiting an answer to see if the oil ring is a single ring or 3 piece. although its a bit pricy its still cheaper then all the machine work and the r made to fit my cb550. all i gotta do is bore the sleeves. if there is anything else i should be aware of please let me know.. thanks all for the help.. i will be on here quite a bit while i am trying to build this bike.

Lykowsky · « **Reply #20 on:** December 13, 2010, 04:10:16 PM »

Hi, sorry for picking up

Right, I know there was few topics rolling about the same stuff but what i need is to get out of doubt

I would really appreciate any definitive info about

I have got 61 pistons with matching pin diameter and just want to double check

are there any differences between sleeves thickness in CB500 vs 550 I couldn't say exactly from ebay photos.#

i up to bore out my cb500 cylinders if there will be possibility to do it but if i'll need to put aftermarket sleeves i'll just go for 550 cylinders.

sorry for diggin it up

Lykowsky

Terry in Australia · « **Reply #21 on:** December 13, 2010, 04:34:38 PM »

I did the Henry Abe 61mm big bore kit install for another member here last year, as has been said before, I had to machine the oil ring groove out a tad to allow fitment of CB750 3 piece oil rings, on the insistence of the owner.

Personally, I think the whole "single piece oil ring" thing is balls, the CB750K0 and K1 came with 1 piece oil rings, and my K0 that I sold recently was still chugging along after 40 years and didn't blow a puff of smoke. My 836cc race engine is fitted with RC/Arias 65mm 12:1 comp pistons, (with 1 piece oil rings) and once again, even after 3 or 4 years of "spirited" riding with many 10,000 RPM(+) runs on my favorite road, no smoke.

Buy the Henry Abe kit, and just get your 550 cylinders bored to suit. (the OD of the included Henry Abe sleeve's is smaller than the OD of the 550's OEM sleeves, as they're meant for a 500) Cheers, Terry.

Lykowsky · « **Reply #22 on:** December 14, 2010, 12:51:09 PM »

Sorry for puting the topic on the wrong track because the thing i'm up for is a bit different than you want to explain me.

Right so i have got CB500 engine and want to keep it classy like that, but i have bought recently wiseco forged piston kit for cb650 and i want to match it with my engine using cb650 head wnd bored out cb500 cylinders.

The point is that i have got cb500 cylinders with 56 bore rather than 58 like in 550

but the question is what is the nominal diameter from outer edge for cb500 and cb550

talking straight can i just go and bore out my cb500 liners or i have to buy cb550 liners and bore them out because 500 ones will not be enough meat to do it.

sorry for repeating but cannoc find straight answer and don't want to end up buying 550 top end when i can just bore out mine

Lykowsky

TwoTired · « **Reply #23 on:** December 14, 2010, 02:11:10 PM »

Can you bore the 500 cylinders to fit 59.8mm pistons? Yes.

Should you? Probably not. The cylinder material gets pretty thin in this situation. I'd worry about uneven cylinder heating and distortion, which is more stable/consistent with a thicker cylinder wall.

Looking at it another way, Honda offered pistons in 4 over bore sizes. The biggest overbore was 1mm over stock. I speculate that Honda considered the thinning cylinder wall and limited the wall loss by limiting the overbore size. (Or, they reasoned that the lower end would be beyond wear limits after 4 top overhauls.)

With this understanding, the biggest safe overbore with the CB500 liners would be 57mm.
The biggest safe (Honda extrapolated standard) overbore with the CB550 liners would be 59.5. Technically the 650 pistons of 59.8, are slightly beyond Honda expectations. However, 61mm pistons have been used successfully in Cb550 cylinders. So, in theory, we could apply that same 2.5mm overbore to the CB500 as well, making the largest overbore for the CB500 at 58.5mm. Using Cb650 standard size pistons of 59.8mm in Cb500 cylinders, puts you firmly in the experimentation category. And, if you ever score a cylinder wall, another over bore isn't very attractive. On the other hand, 59.8mm pistons fitted into Cb550 cylinders is still under the 61mm size that has been known to "work".

So, how much risk are you willing to take?

Cheers,

Lykowsky · « **Reply #24 on:** December 15, 2010, 04:34:03 AM »

Right so i'll take responsibility of building 61mm Pistons with cb550 liners.

but only the thing is not clear for me is that if the cb550 bores have bigger diameter of bottom thin part of the sleeves that sits in the crankcase than 500, than modification of crank case shoulb be undertaken in case of putting cb550 liners

Lykowsky

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Author Topic: WILL A CB500 BIG BORE KIT 605CC WORK ON A CB550??? (Read 10025 times)

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