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Author Topic: High CR 500-550 pistons anybody?  (Read 26612 times)

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Offline bwaller

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Re: High CR 500-550 pistons anybody?
« Reply #50 on: November 10, 2008, 06:17:42 PM »
How about a pic of those moham? What is the finished compression height?
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Offline moham

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Re: High CR 500-550 pistons anybody?
« Reply #51 on: November 10, 2008, 09:57:20 PM »
Here are a couple shots... don't know yet how to account for the lost material from the valve pockets. I've been reading up on how to make all the necessary calculations, so that is next...
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Offline crazypj

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Re: High CR 500-550 pistons anybody? (Stickied until Aug 23rd)
« Reply #52 on: November 10, 2008, 11:29:59 PM »
Quote from: bistromath on July 24, 2008, 05:23:54 PM
Sounds like most people are interested in the 62mm. Are there issues with sleeves being too thin when boring to 62? Overheating? Can anyone comment firsthand?

 I'm not 100% sure but I think 61mm is the biggest you can get into stock 550 liners.
I haven't been inside one for several years so cant remember exact liner thickness after boring.
I ran my 550 with modified stock 750 pistons for years and over 70,000 miles.
PJ 
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #53 on: November 11, 2008, 01:14:37 AM »
Hei Bwaller, I knew you'd keep an eye on these....

Looks good as the compression height of these Ninjas seems quite high.

Mohan, could you measure that height? Stock CB500-550 is 23, center line of gudgeon pin to top piston surface. Simply insert a caliper in the gudgeon pin hole, measure and add 7.5mm (half the pin's diameter)

If it's more than 23, you could gain back someo of the volume of the valve pockets by lowering the deck and turning the pistons. what Ninja are these from BTW?

Tg
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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #54 on: November 11, 2008, 01:53:39 AM »
From the center of the wrist pin to the top of the pistons is 23mm on the '85 ninja pistons.
Identical to cb550 pistons.
I am comparing to a set I got from paulages.


Considering that there are the 4 valve reliefs, but a larger OD to the pistons...
I'm guessing the compression should end up in the range of stock.

But I was unable to properly measure the cc's that the 4 valve relief takes up.(no pippette/burrette)

have fun.....


Kinda wish that the cb650 pistons would work.
But with the dome on top of the pistons, I doubt it would work without using a cb650 head as well...
then you might as well get the cam etc...


For a custom set of pistons, 3000$!!!! for the tooling alone??


I have talked to.... not sure who the mfg. was offhand, will re-post when i get home.... but I was quoted 600.00 per piston set for a custom made set of pistons.(with rings for those pistons too)
I was hunting for major(65+mm) overbore options. They said I could send in my piston, and they would make the new pistons to match the CR of the stockers.
Cometic quoted me 150.00 for a cb650 gasket any bore diameter.

Took another route, and used stock cb750 F pistons in my 650.(took machining the pistons though, deck height was too high)







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Offline moham

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Re: High CR 500-550 pistons anybody?
« Reply #55 on: November 11, 2008, 05:56:27 AM »
Like Soos said, they are both right at 23 (I got slightly under 23 for both, 22.6 for stock and 22.5 for ninja, am I measuring from the right spot?)

When I measured from the bottom of the skirt to the top of the piston, it looked like the ninja piston was just slightly longer at 48.75. They seem a little beefier too, but haven't weighed them.

Any easy methods out there for determining the volume of the cut-outs?
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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #56 on: November 11, 2008, 06:06:05 AM »
What are you measuring with?


Oh, and that piston company is Arias....I think.

I don't have it on the 'puter, it's in my little black book of info about my '79 cb650 mods.
Not sure where that is.

l8r
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Just think to yourself what would Alowishus Devander Abercrombie do?
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Offline moham

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Re: High CR 500-550 pistons anybody?
« Reply #57 on: November 11, 2008, 07:19:39 AM »
Quote from: Soos on November 11, 2008, 06:06:05 AM
What are you measuring with?

I've got a digital caliper made by General.
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74 550-The Cherry Picker
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #58 on: November 11, 2008, 07:30:35 AM »
We'll, if its 23mm, then you will still have to mill the block a bit to get the right squish between piston and head. In my racer I went for 0.8mm, I'd say that for the street go for 1mm. Judging from the burn patterns on the piston form my motor, I'd say this is one of the most important thing to do in a hoped up engine.

TG

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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #59 on: November 11, 2008, 07:56:41 AM »
Quote from: moham on November 11, 2008, 07:19:39 AM
Quote from: Soos on November 11, 2008, 06:06:05 AM
What are you measuring with?

I've got a digital caliper made by General.
Did you make sure to measure past the circlip groove?

The bore where the wrist pin rides is a smaller bore than the area outside of the circlip.
It's bored larger to prevent any burrs made when you pull out the circlip the wrist pin does not get scratched on removal/installation.

I might have cheated... I used a co-axial indicator, a mill and a edge finder.
 ;D

l8r
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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #60 on: November 11, 2008, 08:03:35 AM »
And that piston manufacturer was Arias.

their phone # is :
(310) 532-9737

I was quoted 600 per set, no price break until 6(?)+ sets were ordered.
Believe it was for 4 pistons and rings.


It's been a while.


l8r
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Just think to yourself what would Alowishus Devander Abercrombie do?
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Offline moham

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Re: High CR 500-550 pistons anybody?
« Reply #61 on: November 11, 2008, 08:04:06 AM »
Quote from: Soos on November 11, 2008, 07:56:41 AM

Did you make sure to measure past the circlip groove?

The bore where the wrist pin rides is a smaller bore than the area outside of the circlip.
It's bored larger to prevent any burrs made when you pull out the circlip the wrist pin does not get scratched on removal/installation.

I was curious about that and tried to make sure I got to where the pin resides, but the caliper jaws having a flat edge might have cheated the measurement. It seems like every time a buy a tool I quickly find the need for a different one.
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74 550-The Cherry Picker
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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #62 on: November 11, 2008, 08:07:15 AM »
If you closely measure the larger bore area on the outside of the piston past the circlip, you can use that measurement instead of the pin diameter and get the deck height.



l8r
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Just think to yourself what would Alowishus Devander Abercrombie do?
"Brix will be shat by your neighbors." - schwebel
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #63 on: November 11, 2008, 09:55:23 AM »
easiest might be simply mouniting the two pistons on one pin and comparing compression height :-)

TG
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Offline bwaller

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Re: High CR 500-550 pistons anybody?
« Reply #64 on: November 11, 2008, 10:10:32 AM »
These certainly are a possibility, but even with the same compression height, there will be some reduction in C/R with that dished crown & four valve pockets.

TG, I'm still going to pursue the other option for now....
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #65 on: November 12, 2008, 07:59:30 AM »
Hei fish, that's interesting.... thing is that if i recall right, those early dreams had quite a lot of anlge between the valves and thus needed quite a lot of dome. 500's-550's chambers are much flatter (good for quick combustion) and the dome of those 305 jugs might be to much for us.

Have a good pic of these 305's pistons?

TG
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Offline Triffecpa

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Re: High CR 500-550 pistons anybody?
« Reply #66 on: November 12, 2008, 10:06:37 AM »
you can get some sketchy pics of the pistons thru www.servicehonda.com  They show stock pistons and a couple of the oversize ones still available at about $60-65 each.  Rings are separate.

TR
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Offline Triffecpa

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Re: High CR 500-550 pistons anybody?
« Reply #67 on: November 12, 2008, 10:37:31 AM »
got a few on Ebay at the moment:

Item number: 220298996866

Item number: 110311365117  (this one has better pics)

Tracy
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Offline Triffecpa

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Re: High CR 500-550 pistons anybody?
« Reply #68 on: November 12, 2008, 10:40:19 AM »
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #69 on: November 13, 2008, 03:59:26 AM »
forget it, WAAAAYYY too much dome for our SOHC's
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Offline Soos

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Re: High CR 500-550 pistons anybody?
« Reply #70 on: November 13, 2008, 05:17:54 AM »
I dunno.... might work for a cb650.
But I think they would still need machining a bit.


l8r

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Just think to yourself what would Alowishus Devander Abercrombie do?
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #71 on: November 13, 2008, 10:50:41 AM »
maybe the syandard, low compression type, those high CR in ebay just wont fit, me thinks.
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Offline bwaller

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Re: High CR 500-550 pistons anybody?
« Reply #72 on: November 13, 2008, 12:33:18 PM »
Yea, way too much dome there.
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Offline turboguzzi

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Re: High CR 500-550 pistons anybody?
« Reply #73 on: November 13, 2008, 03:02:48 PM »
Unless you want to run 14:1 CR on methanol :-)

more to the point, typical 60's high perfomance design, big inclined valves, deep chambers, very prone to detonate.
The CB750 heads have some heritage from them times.

TG
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Offline kayaker43

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Re: High CR 500-550 pistons anybody?
« Reply #74 on: November 13, 2008, 08:25:31 PM »
XL175 pistons are 64mm and XL185 are 63mm. These look interesting, I wonder if they are still available from Honda? Also heard to look at KZ650. Anyone know the max botre for CB650 sleeves?

Here's and interesting site listing many bore sizes http://www.imoto.co.za/pistons.htm
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