Author Topic: Cheap 836 kits back on ebay...$110! *Update!  (Read 110465 times)

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Offline Elan

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #125 on: September 15, 2011, 09:04:55 AM »

.
Is it an "F" head or an "F2" head mate? If it's an F head you won't lose any compression, if it's an F2 (or F3) head you will lose a fair bit of compression, and it'll leak oil. Cheers, Terry. ;D
[/quote]

Yeah its an f2 head. I didnt know until I was reassembling. Doesnt leak though.  Are you talking about leaking through the extra oil passages?  It was actually leaking at first because I made the dummy move of connecting the valve vent to the oil tank. Pressure built up fast and pushed oil up and out the extra drains of the cylinders. Doesnt happen when the vent is actually venting though :).
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Offline Terry in Australia

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #126 on: September 17, 2011, 03:56:21 PM »
Well I'm surprised that it doesn't still leak mate, there's another thread here about why it should leak and the fix required (some engineering is involved) but if it's not leaking, you've done well. Cheers, Terry. ;D
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Offline coma13

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #127 on: September 18, 2011, 03:05:21 PM »
is there any formula for the increase in compression ratio for the amount of cylinder decking with this kit installed? I'd like to pump it up to around 10:1 if possible.
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Offline lucky

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Re: Cheap 836 kits back on ebay...$110!
« Reply #128 on: September 18, 2011, 03:48:07 PM »
I just bought a set.My no.2 cylinder is smoking so I need to do a top end eventually and the price is great.

If it just smokes on start up or off idle it could just be a valve guide seal.
You can replace those without taking the head off .

Offline Terry in Australia

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #129 on: September 18, 2011, 03:52:29 PM »
is there any formula for the increase in compression ratio for the amount of cylinder decking with this kit installed? I'd like to pump it up to around 10:1 if possible.

Is your bike a K, F, or F2/3 mate? If it's a black engine there's no way you'll get 10:1, but with the other engines the extra displacement with an unmodified combustion chamber would get you close to those numbers with a light head and deck skim. Cheers, Terry. ;D 
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline coma13

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #130 on: September 19, 2011, 01:33:59 AM »
is there any formula for the increase in compression ratio for the amount of cylinder decking with this kit installed? I'd like to pump it up to around 10:1 if possible.

Is your bike a K, F, or F2/3 mate? If it's a black engine there's no way you'll get 10:1, but with the other engines the extra displacement with an unmodified combustion chamber would get you close to those numbers with a light head and deck skim. Cheers, Terry. ;D

K. Sorry, I should have mentioned that. As of now the head is unmodified but I was planning on getting some MRieck head work done at the same time as the cylinder boring. I'm not sure if he does anything with the combustion chamber on the standard level2 or whatever I go with.
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Offline coma13

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #131 on: September 26, 2011, 07:41:31 PM »
Anybody got any input on my previous question? What sort of compression ratio increase can I expect with what amount of decking if nothing else is altered in the stock combustion chamber?
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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #132 on: September 26, 2011, 07:44:41 PM »
Anybody got any input on my previous question? What sort of compression ratio increase can I expect with what amount of decking if nothing else is altered in the stock combustion chamber?

If you really want the right answer try sending Mike Rieck a PM....... ;)
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Offline HondaMan

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #133 on: October 07, 2011, 06:44:51 PM »
Anybody got any input on my previous question? What sort of compression ratio increase can I expect with what amount of decking if nothing else is altered in the stock combustion chamber?

Well...you might be looking in the wrong direction, or possibly asking the wrong question? The "dead" info is: the stock heads ranged from 22.0cc (K0 sandcast) to 23.8cc (F2/3), with 22.6cc being the 'nominal' value during the K1-K6 series.

But: the cylinders in mid-year K3 (thru K6) became 1mm taller (it was part of improving MPG and the U.S. gas crisis of the time) while the chambers tended to come in around 22.2-22.4cc. In the K4/5, the valves tended to be recessed into the heads, and not evenly, causing shrouding and uneven breathing, with attendant loss of power. And, in any given head, the chambers can range from 22.2cc to 22.8cc, very common variations until the F1 engines appeared.

The real issue might be: how much flow improvement can be provided with a given head and piston combination? The domed pistons cause a loss of flow as compared to the flat-topped pistons, especially in the all-important 4000-6000 RPM range. The higher domed pistons make this worse: Wiseco tries to offset the loss of low-end torque from their domes with their higher 10.25:1 compression ratio, as one example of a way to work around the difference. The once-popular 811cc pistons (square bore at 63x63mm) came in both the flat-topped types and the 11:1 types from Powroll: the former were far more 'even' in power on the street, while the latter worked up more HP at the high RPMs, once the extra-light valve keepers, stronger springs, trimmed and polished valves, and extra flycut pistons, with the HD cylinder studs, were ALL also added to the engine.

Once the compression squish reaches above 10:1 on these engines, the piston-valve clearance must be carefully controlled, and $$ add up quickly from it. And, the biggest power losses these engines suffered were from poorly made ports and large variants in the cylinder fins (flash leftovers) that caused heat buildup in uneven ways.

Generally, using larger pistons (836cc) means the throttle becomes the intake valve. So, anything that can be done to improve on this restriction will improve the flow, too. I find the deshrouding, quench band addition, port shape and smoothing, valve polishing, guide narrowing, and head detailing and chamber balancing can make within a few HP of the larger inlet valves: to go to the max, MRieck can add the latter for you, too. ;)
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Offline jneuf

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #134 on: October 07, 2011, 09:33:29 PM »
Great info HondaMan!!

So are you saying that if I put my K0 head and cylinders on my k8 engine I'd see a bump in compression, and no shrouding?

Did Honda ever make any changes to intake and exhaust ports from the K0 to K8 engine?
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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #135 on: October 08, 2011, 09:15:43 PM »

So are you saying that if I put my K0 head and cylinders on my k8 engine I'd see a bump in compression, and no shrouding?

You still have to make a quench band and deshroud the valve when going to 836. It doesn't matter which series of engines are being used. The mechanical design did not change between the engines (despite popular opinion!). The 1-2 gears changed, the rods and cams changed slightly (still interchangeable), and different pistons were installed, with minor casting changes in the head chambers to accommodate the domed pistons, but that was about it (exception: F2/3 valves).

Quote
Did Honda ever make any changes to intake and exhaust ports from the K0 to K8 engine?

Starting in the K5, the molds for the ports took on a decidedly more controlled appearance. In other words, the dies got better, so the port shapes became more like the drawings and less like little sandbags that had been hand-fitted inside the molds, shifting with finger pressure and molten metals pressing against them. :)
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Offline classic bike tuner

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #136 on: October 09, 2011, 02:43:37 AM »
Anybody got any input on my previous question? What sort of compression ratio increase can I expect with what amount of decking if nothing else is altered in the stock combustion chamber?

try fitting cb 900 rods [1,5 mm longer] and take  of material from  the pistons on the  top edge  leave a squis area of about 0,8 mm

compression wil become little higher as standard

Offline coma13

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #137 on: October 09, 2011, 05:30:54 PM »
Anybody got any input on my previous question? What sort of compression ratio increase can I expect with what amount of decking if nothing else is altered in the stock combustion chamber?

Well...you might be looking in the wrong direction, or possibly asking the wrong question? The "dead" info is: the stock heads ranged from 22.0cc (K0 sandcast) to 23.8cc (F2/3), with 22.6cc being the 'nominal' value during the K1-K6 series.

But: the cylinders in mid-year K3 (thru K6) became 1mm taller (it was part of improving MPG and the U.S. gas crisis of the time) while the chambers tended to come in around 22.2-22.4cc. In the K4/5, the valves tended to be recessed into the heads, and not evenly, causing shrouding and uneven breathing, with attendant loss of power. And, in any given head, the chambers can range from 22.2cc to 22.8cc, very common variations until the F1 engines appeared.

The real issue might be: how much flow improvement can be provided with a given head and piston combination? The domed pistons cause a loss of flow as compared to the flat-topped pistons, especially in the all-important 4000-6000 RPM range. The higher domed pistons make this worse: Wiseco tries to offset the loss of low-end torque from their domes with their higher 10.25:1 compression ratio, as one example of a way to work around the difference. The once-popular 811cc pistons (square bore at 63x63mm) came in both the flat-topped types and the 11:1 types from Powroll: the former were far more 'even' in power on the street, while the latter worked up more HP at the high RPMs, once the extra-light valve keepers, stronger springs, trimmed and polished valves, and extra flycut pistons, with the HD cylinder studs, were ALL also added to the engine.

Once the compression squish reaches above 10:1 on these engines, the piston-valve clearance must be carefully controlled, and $$ add up quickly from it. And, the biggest power losses these engines suffered were from poorly made ports and large variants in the cylinder fins (flash leftovers) that caused heat buildup in uneven ways.

Generally, using larger pistons (836cc) means the throttle becomes the intake valve. So, anything that can be done to improve on this restriction will improve the flow, too. I find the deshrouding, quench band addition, port shape and smoothing, valve polishing, guide narrowing, and head detailing and chamber balancing can make within a few HP of the larger inlet valves: to go to the max, MRieck can add the latter for you, too. ;)

Thank you very much for the in-depth response! Eye opening, as usual. PS: I sent you an email.
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Offline Prospect

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #138 on: October 10, 2011, 10:47:11 AM »
Well that sucks!  He ships all over the world except Canada!!! Wonder why?
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Offline jneuf

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #139 on: October 10, 2011, 11:49:33 AM »
I had mine shipped straight to Canada
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Offline FuZZie

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #140 on: October 10, 2011, 12:29:23 PM »
Well that sucks!  He ships all over the world except Canada!!! Wonder why?

I think you miss read something
Quote
Ships to:   Worldwide See shipping location exclusions
"exclusions" is a link to the order page showing this info:
Quote
Shipping to: Worldwide
Excludes: US Protectorates, Reunion, Japan

Offline Prospect

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #141 on: October 10, 2011, 06:37:39 PM »
Well that sucks!  He ships all over the world except Canada!!! Wonder why?

I think you miss read something
Quote
Ships to:   Worldwide See shipping location exclusions
"exclusions" is a link to the order page showing this info:
Quote
Shipping to: Worldwide
Excludes: US Protectorates, Reunion, Japan

Sorry.  I looked at his other items for sale and he doesn't ship some of them to Canada (front sprocket is an example).  It seems like he ships this kit to Canada. 
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Offline Grnrngr

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #142 on: October 10, 2011, 06:45:23 PM »
You mean...Canada's NOT a U.S. Protectorate?  :D  (laughing and dodging snowballs..)
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Offline joe29

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #143 on: October 25, 2011, 01:07:54 PM »
Can anyone explain the difference between the two auctions from this seller?  One auction is labeled "65mm" and the other is labeled "836cc".  I emailed the seller and he said they're the same.  Can someone explain/confirm?

65mm auction:
http://www.ebay.com/itm/69-77-HONDA-CB750K-PISTON-BIGBORE-65mm-SET-GASKET-/140577656369?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item20bb14ce31

836cc auction:
http://www.ebay.com/itm/69-77-HONDA-CB750K-836cc-BIGBORE-PISTON-KIT-W-GASKET-/140568653706?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item20ba8b6f8a
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Offline Rigid

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #144 on: October 25, 2011, 01:09:42 PM »
common eBay tactic to cast a wider net, although, he could have mentioned both in each auction.
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Offline bert96

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #145 on: October 25, 2011, 01:58:26 PM »
Well that sucks!  He ships all over the world except Canada!!! Wonder why?

I think you miss read something
Quote
Ships to:   Worldwide See shipping location exclusions
"exclusions" is a link to the order page showing this info:
Quote
Shipping to: Worldwide
Excludes: US Protectorates, Reunion, Japan

Sorry.  I looked at his other items for sale and he doesn't ship some of them to Canada (front sprocket is an example).  It seems like he ships this kit to Canada. 

I bought a kit with no shipping problem,i'm from Quebec/Canada.

Bert
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Offline Prospect

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #146 on: November 08, 2011, 08:31:09 AM »
Well that sucks!  He ships all over the world except Canada!!! Wonder why?

I think you miss read something
Quote
Ships to:   Worldwide See shipping location exclusions
"exclusions" is a link to the order page showing this info:
Quote
Shipping to: Worldwide
Excludes: US Protectorates, Reunion, Japan

Sorry.  I looked at his other items for sale and he doesn't ship some of them to Canada (front sprocket is an example).  It seems like he ships this kit to Canada. 

I bought a kit with no shipping problem,i'm from Quebec/Canada.

Bert

Interesting.  All his ads for the big bore kit say he doesn't ship to Canada.  I've contacted him about shipping here but haven't heard an answer. 

http://www.ebay.com/itm/69-77-HONDA-CB750K-836cc-BIGBORE-PISTON-KIT-W-GASKET-/140568653706?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item20ba8b6f8a

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Offline Doum

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #147 on: November 08, 2011, 09:37:56 AM »
Yes they changed the setting about shipping for this kit in the last week.I ordered mine with the help of a US member that will send it back to me.
I wonder what is the difference between ship a gasket and a piston kit.....cuase there is many item that he accept to ship to canada

Offline Prospect

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #148 on: November 12, 2011, 07:22:35 PM »
I never heard a reply from the seller.  Ended up having a buddy of mine in Texas order one and he's gonna ship it here.
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1971 CB750K1
1972 CB750K1
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1975 GL1000 Goldwing
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #149 on: December 02, 2011, 07:35:42 PM »
Just ordered mine! Looks like I got a winter project.  ;D
So much to do, so little time.