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Author Topic: 592 overbore. What do I need to tell the machinist?  (Read 4774 times)

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Offline Shenanigans

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592 overbore. What do I need to tell the machinist?
« on: June 22, 2009, 11:44:37 PM »
May be a stupid question, but... I am dropping off my 550 jugs and 750 pistons as soon as my rings arrive in the mail. Will the machinist be able to figure out exactly what to bore it to with the pistons/rings in hand? If not what exact bore should I tell him for standard 750 pistons and a set of std. rings? I should run the stock ring gap of .2mm, right?

Or is all of this null and void since he will know what to do?

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Offline bryanj

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #1 on: June 23, 2009, 04:48:30 AM »
You need a real top notch machinist to do this without the replacement liners as the originals get VERY thin at the bottom
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Offline bwaller

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #2 on: June 23, 2009, 07:53:02 AM »
The sleeves are thin after so Bryan is right, get a good shop to do the work. Take him all four pistons. I'm surprised you haven't heard from anyone yet but piston/cylinder clearance of 0.0012 -+ 0.0002, seems to be a good number for Honda pieces.

Use the stock 750 ring end gap
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #3 on: June 23, 2009, 09:42:17 AM »
You didn't say what they are charging so you might want to consider shipping them to Jay at APE. I understand Jay does most of the work himself on our old Hondas. I just had my liners replaced and bored for $300. I supplied the liners. Very reasonable especially since Jay knows what he's been doing to these bikes for 40 years. I think he needs to autograph them somewhere.
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #4 on: June 23, 2009, 05:18:44 PM »
Quote from: bwaller on June 23, 2009, 07:53:02 AM
The sleeves are thin after so Bryan is right, get a good shop to do the work. Take him all four pistons. I'm surprised you haven't heard from anyone yet but piston/cylinder clearance of 0.0012 -+ 0.0002, seems to be a good number for Honda pieces.

Use the stock 750 ring end gap

Those were the clearance numbers I was looking for, thanks!

The shop I am taking it to has a reputation for very good work. I hope its true. He is also a teacher at a tech school and likes to try to explain/teach as much of the process as he can, so its really a 2 fold opportunity for me to actually learn something.

I do however need my head ported, while I have your attention, whats APEs going rate for a mid level port job?



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Offline mlinder

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #5 on: June 23, 2009, 05:22:35 PM »
Quote from: Shenanigans on June 23, 2009, 05:18:44 PM
Quote from: bwaller on June 23, 2009, 07:53:02 AM
The sleeves are thin after so Bryan is right, get a good shop to do the work. Take him all four pistons. I'm surprised you haven't heard from anyone yet but piston/cylinder clearance of 0.0012 -+ 0.0002, seems to be a good number for Honda pieces.

Use the stock 750 ring end gap

Those were the clearance numbers I was looking for, thanks!

The shop I am taking it to has a reputation for very good work. I hope its true. He is also a teacher at a tech school and likes to try to explain/teach as much of the process as he can, so its really a 2 fold opportunity for me to actually learn something.

I do however need my head ported, while I have your attention, whats APEs going rate for a mid level port job?





Dunno, but sending it to Mike Reick for a stage one or two might be a good idea...
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #6 on: June 23, 2009, 06:00:57 PM »
Err.. yeah, I meant to say Mike R.

I know a lot of people on this forum have had him do their heads, I am just looking for a ballpark price. Anyone?
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Offline bwaller

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #7 on: June 23, 2009, 06:30:07 PM »
Best to send Mike a pm.
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Offline moham

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #8 on: June 23, 2009, 06:32:24 PM »
Quote from: Shenanigans on June 23, 2009, 06:00:57 PM
Err.. yeah, I meant to say Mike R.

I know a lot of people on this forum have had him do their heads, I am just looking for a ballpark price. Anyone?

It all depends on what you want him to do...He needed to have new valve seats cut for mine as well as a bit of welding so it was more. He will email you a price list if you pm or email him....

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Offline MRieck

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #9 on: June 23, 2009, 07:40:13 PM »
Quote from: moham on June 23, 2009, 06:32:24 PM
Quote from: Shenanigans on June 23, 2009, 06:00:57 PM
Err.. yeah, I meant to say Mike R.

I know a lot of people on this forum have had him do their heads, I am just looking for a ballpark price. Anyone?

It all depends on what you want him to do...He needed to have new valve seats cut for mine as well as a bit of welding so it was more. He will email you a price list if you pm or email him....


Yes ..it all depends on what needs to be replaced. This is old stuff BUT it can be made new ;) With cast pistons I'd stay on the .0012 side of things. ;)
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Offline Sam Green Racing

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #10 on: June 23, 2009, 07:52:20 PM »
Be carefull with that bad elbow, I want you in fine fettle come November. ;D ;D ;D ;D ;D ;D

Sam. ;)
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #11 on: July 09, 2009, 02:55:52 AM »
Went to the machinist today, he decided he did not want to touch them. "Too small, no idea about the pistons"  >:(
Went to 2 other places. Same answers. I have a few more numbers left to call but I think they will tell me the same thing. For some reason "motorcycle specific" actually means Harley specific.
One day after winning the lottery I'm going to buy all the equipment I will ever need so I dont ever has to rely on other people doing/not doing #$%*.
So I might be sending them off to APE.

Are there any other known options for more modern pistons that DONT have to be machined to fit?

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Offline d_soles

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #12 on: July 09, 2009, 03:55:12 AM »
Sounds typical.  No one actually wants to do any good work these days.  You'd think a machine shop could make anything out of a hunk of metal, but, those machinists aren't even real machinists anymore....sad.

Doug
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Offline MRieck

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #13 on: July 09, 2009, 06:00:31 AM »
Quote from: Shenanigans on July 09, 2009, 02:55:52 AM
Went to the machinist today, he decided he did not want to touch them. "Too small, no idea about the pistons"  >:(
Went to 2 other places. Same answers. I have a few more numbers left to call but I think they will tell me the same thing. For some reason "motorcycle specific" actually means Harley specific.
One day after winning the lottery I'm going to buy all the equipment I will ever need so I dont ever has to rely on other people doing/not doing #$%*.
So I might be sending them off to APE.

Are there any other known options for more modern pistons that DONT have to be machined to fit?


You need to find a real motorcycle oriented machine shop.....I'm not surprised the guy didn't want to work on it. Harry's Machined Parts in Massachusetts is such a place as is APE
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #14 on: July 09, 2009, 08:23:16 PM »
Success? Basko engine service said they would do it for 225-250. Bored and honed.

Now I still got to worry about the pistons...

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Offline B.O.X.N.I.F.E.

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #15 on: July 09, 2009, 09:19:09 PM »
Do you have a copy of the gentlemans express article? I thought it had pretty specific instructions for what needed to be removed from your 750 pistons.
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #16 on: July 09, 2009, 10:36:05 PM »
The problem is not what to do but finding someone to do it.


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Offline B.O.X.N.I.F.E.

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #17 on: July 11, 2009, 02:49:39 AM »
Have you checked with any local dirt bike shops? Dirt bikes need overbores much more often than street bikes, often you can't just rering and hone them. Or maybe an ATV shop?
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and a couple years later, 38 days and 9,102 miles...

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Offline Terry in Australia

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #18 on: July 11, 2009, 06:09:56 AM »
I'm very lucky that I've "inherited" a beautiful old "Repco" boring bar that will bore anything up to 3 inches or so, and I bored Al Harper's 550 cylinders out to 61mm to suit his "Henry Abe" "605" (actually 592cc) kit.

Considering that you're running CB750 OEM (?) pistons, here are the specs from a CB750 manual:

Cylinder dia: 2.4022-2.4024 in (61.01-61.02mm)
Limit of wear: 2.3957 in (61.1mm)
Piston ring end gap: 0.008.in (0.2mm)
Piston wear limit: 2.3957 in (60.85mm)

And yes, boring 550 sleeves does make them somewhat "thin", but not as thin as a CB750 836cc or (shudder) CycleX's 850cc kit, you could use one of those sleeves for a gasket punch! Cheers, Terry. ;D
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Offline moham

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #19 on: July 11, 2009, 06:52:52 AM »
Shenanigans, have one of the shops you've taken this to refer you to somebody locally for the work. You're in AZ right? Surely there are plenty of shops that do bikes. I had to call a few places before I got referred to the shop that bored my 550 to 60mm. Keep looking, somebody will turn up...


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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #20 on: July 11, 2009, 10:15:46 AM »
Just send them to Big Jay at APE. You won't have to tell him anything, he knows what to do. 600,000 people in the area and you'd think someone would do bikes. Wrong. Not serious bike stuff anyway. I quit jacking around with the local auto machine shop. Funny thing, the local guy seems to let you think he knows how to do stuff but he never did it. Guess it's not as easy, fun, or profitable as building a 800hp engine and dynoing it in.  
« Last Edit: July 11, 2009, 10:18:29 AM by Jerry Rxman Griffin »
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Offline Terry in Australia

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #21 on: July 11, 2009, 02:27:21 PM »
Nah, it's more that the boring bars used for car engines are just too big for bikes Jerry, like you say, better to go to a dedicated bike engineer like APE, they aren't cheap, but they're very, very good.............  ;D
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So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #22 on: July 11, 2009, 03:08:06 PM »
Alright, Alright I'm convinced :) APE shall get them.


Will they do my pistons too?  ;D
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Offline Shenanigans

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #23 on: July 19, 2009, 05:18:24 PM »

The pistons via the gentleman's express article is not going to work out. I cant assemble the motor then clay the cylinders 3 or 4 times until I get the valve pockets right. Its a way bigger project than I thought. Nor do I want to pay someone else a grand to do it. I think there has to be easier alternatives. I saw the 74 550 hybrid thread but I really wanted to bump up the compression.

Any Ideas? These pistons are the LAST thing keeping this project from starting.







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Offline moham

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Re: 592 overbore. What do I need to tell the machinist?
« Reply #24 on: July 19, 2009, 05:41:52 PM »
Not that it's too much help but the only options I would say are 1) try to pick up one of the "605" kits that come up from time to time (although I don't know if those kits bump your CR) or 2) try to talk one of the forum members who have done the piston mod into helping you with the valve reliefs and cut-outs (I know Strongperf has got this mod going right now and I believe he's doing some of the work himself)...
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