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Author Topic: Stroker options  (Read 5357 times)

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Offline afkrejci90

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Stroker options
« on: June 10, 2012, 09:25:32 PM »
This has probably been discussed but I can't find anything that relates to my exact model.  I looked up to see what the cost would be to make my 78 750 crank into a stroker and it's close to $1100.  Are there any alternatives like using a crank from a different engine that won't put a hole in my wallet? 
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Offline Retro Rocket

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Re: Stroker options
« Reply #1 on: June 10, 2012, 10:10:13 PM »
I know that 900 Honda cranks {DOHC} get used i these engines but i don't know a great deal about it....  I think it would still work out expensive because the 900's use a Hyvo chain set up...
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Offline BLUE71TURBO

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Re: Stroker options
« Reply #2 on: June 10, 2012, 10:16:56 PM »
 Either way it's gonna be expensive $$$$ ! !   Modified crankshaft + pistons + rods = $$$$$ !   :o   :(  :'( :'( :'(
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Offline bear

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Re: Stroker options
« Reply #3 on: June 11, 2012, 04:15:26 AM »
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Offline mec

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Re: Stroker options
« Reply #4 on: June 11, 2012, 04:21:20 AM »
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Offline bear

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Re: Stroker options
« Reply #5 on: June 11, 2012, 04:26:14 AM »
+6mm from memory Mec.
I'm happy to be corrected.

Cheers,
Brian
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Offline mec

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Re: Stroker options
« Reply #6 on: June 11, 2012, 04:29:46 AM »
i always thought the same stroke as standard 750 but with hivo primary chain.
dohc 900 has +5mm (69mm instead of 64mm), hivo primary as hivo camchain.

mec
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Offline bear

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Re: Stroker options
« Reply #7 on: June 11, 2012, 05:18:15 AM »
Quote from: mec on June 11, 2012, 04:29:46 AM
i always thought the same stroke as standard 750 but with hivo primary chain.
dohc 900 has +5mm (69mm instead of 64mm), hivo primary as hivo camchain.

mec

Your right Mec.
I just checked it out. The auto does indeed have the same stroke as other SOHC's, @ 63mm I think.
I stand corrected. :-[

Cheers,
Brian
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Offline bear

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Re: Stroker options
« Reply #8 on: June 11, 2012, 05:20:32 AM »
Quote from: mec on June 11, 2012, 04:29:46 AM
i always thought the same stroke as standard 750 but with hivo primary chain.
dohc 900 has +5mm (69mm instead of 64mm), hivo primary as hivo camchain.

mec

Your right Mec.
I just checked it out. The auto does indeed have the same stroke as other SOHC's, @ 63mm I think.
I stand corrected.

Cheers,
Brian
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Offline bear

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Re: Stroker options
« Reply #9 on: June 11, 2012, 05:21:50 AM »
Bloody hell I'm stuttering again.

Cheers,
Brian
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Offline mec

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Re: Stroker options
« Reply #10 on: June 11, 2012, 05:45:59 AM »
Quote from: bear on June 11, 2012, 05:20:32 AM
Quote from: mec on June 11, 2012, 04:29:46 AM
i always thought the same stroke as standard 750 but with hivo primary chain.
dohc 900 has +5mm (69mm instead of 64mm), hivo primary as hivo camchain.

mec

 63mm I think.

Cheers,
Brian

:):):) 64mm. originally our sohc was a long stroke engine with 64 stroke and 63 bore.
all the racers made a "quadratical" engine with 64x64 or short stroker with 64x65bore out of it.

mec
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Offline afkrejci90

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Re: Stroker options
« Reply #11 on: June 11, 2012, 08:35:34 AM »
Quote from: mec on June 11, 2012, 04:29:46 AM
i always thought the same stroke as standard 750 but with hivo primary chain.
dohc 900 has +5mm (69mm instead of 64mm), hivo primary as hivo camchain.

mec
Theres alot of mods to do going this route especially since I would need HiVo chains.  At that point getting one made might be the easier option.
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Offline kmb69

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Re: Stroker options
« Reply #12 on: June 11, 2012, 09:56:58 AM »
((PI x (Radius x Radius)) x Stroke) x Cylinders = Displacement

A stock Honda SOHC 750 is 61mm bore x 63mm stroke x 4 cyls = 736cc.
A stock Honda DOHC 750 is 62mm bore x 62mm stroke x 4 cyls = 748cc.

63mm bore x 64mm stroke x 4 cyls = 798cc
64mm bore x 64mm stroke x 4 cyls = 823cc
65mm bore x 64mm stroke x 4 cyls = 849cc
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Offline mec

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Re: Stroker options
« Reply #13 on: June 11, 2012, 11:55:47 AM »
thx to kmb69!

sorry guys, in my prevoius post i mixed some numbers :(
have to check the pills I swallow :)

mec
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Offline Sam Green Racing

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Re: Stroker options
« Reply #14 on: June 11, 2012, 12:23:56 PM »
All the CB750 SOHC4s are 61 bore x 63 stroke = 736557.04cc.

Sam. ;)
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Offline kmb69

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Re: Stroker options
« Reply #15 on: June 11, 2012, 08:42:34 PM »
Was using shorthand.  ;)

I didn't show the conversion from cubic millimeter to cubic centimeter. Divide by 1000.
« Last Edit: June 11, 2012, 08:45:19 PM by kmb69 »
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Offline bear

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Re: Stroker options
« Reply #16 on: June 11, 2012, 10:23:56 PM »
Quote from: SamCR750A on June 11, 2012, 12:23:56 PM
All the CB750 SOHC4s are 61 bore x 63 stroke = 736557.04cc.

Sam. ;)

Not mine! ;D ;D ;D

Cheers,
Brian
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Offline Sam Green Racing

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Re: Stroker options
« Reply #17 on: June 11, 2012, 11:10:17 PM »
Yes Brian but when you make them that big, they become unmanageable. ;D ;D ;D ;D ;D ;D ;D

Sam. ;) ::)
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Offline bear

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Re: Stroker options
« Reply #18 on: June 11, 2012, 11:43:43 PM »
Quote from: SamCR750A on June 11, 2012, 11:10:17 PM
Yes Brian but when you make them that big, they become unmanageable. ;D ;D ;D ;D ;D ;D ;D

Sam. ;) ::)

It wasn't the motor Sammy.
It was the loose nut on the handle bars.

Oh......and by the the by, after three weeks in an induced coma, another three weeks in ICU and five months in rehab I'm walking out of here on Friday!!!!!!!!  (if I pass my nuro syc test) :o

                                               THANK'S TO YOU ALL
                                   :) :) :) :) :) :) :) :) :) :) :) :) :) :) :)
                         
Cheers,
Brian




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Offline Sam Green Racing

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Re: Stroker options
« Reply #19 on: June 12, 2012, 12:45:50 AM »
Great news Brian, good on ya. 8) 8) 8) 8) 8) 8) 8)

Sam. ;)
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Offline Retro Rocket

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Re: Stroker options
« Reply #20 on: June 12, 2012, 02:00:19 AM »
Quote from: SamCR750A on June 12, 2012, 12:45:50 AM
Great news Brian, good on ya. 8) 8) 8) 8) 8) 8) 8)

Sam. ;)

+1000000000000000
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Offline bear

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Re: Stroker options
« Reply #21 on: June 12, 2012, 02:19:04 AM »
Quote from: Retro Rocket on June 12, 2012, 02:00:19 AM
Quote from: SamCR750A on June 12, 2012, 12:45:50 AM
Great news Brian, good on ya. 8) 8) 8) 8) 8) 8) 8)

Sam. ;)

+1000000000000000

Thanks mate  :)
Sorry for the hyjack kmb.

Cheers,
Brian
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Offline Sam Green Racing

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Re: Stroker options
« Reply #22 on: June 12, 2012, 02:32:39 AM »
Good news like that should be hyjacked into every thread. 8) 8) 8) 8) 8)
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Offline jweeks

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Re: Stroker options
« Reply #23 on: June 12, 2012, 04:18:21 AM »
5 mm increase on the stock 750 crank was the limit to oil the bearings where the oil hole is no longer centered. The 900F cranks (US) are heavier and require mild clearancing to the main webs to drop in. To run in a clutch bike, you'll use early Gold Wing clutch parts attached to the 900F primary chain. The 900F crank ends were set up opposite the SOHC 750's, so you have to cut off the snout on one end and machine it for your points plate. The other end is tapped, but I haven't yet heard of anyone connecting starter gear to it. I run one with an external starter. The cam chain is also different between the two. I run a 3 mm spacer below the sleeves for that crank. I put mine in for less than $1,100, but I am racing an automatic.
Almost forgot the primary chain tensioner which must be added for street use. I don't believe that +6 mm is the limit in the 750 case. Big Jim can stroke the 900F cranks as well. (I asked him at Valdosta) ;)

                                                                       Jon Weeks
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Offline bear

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Re: Stroker options
« Reply #24 on: June 12, 2012, 10:58:24 AM »
Quote from: JWEEKS on June 12, 2012, 04:18:21 AM
Almost forgot the primary chain tensioner which must be added for street use. I don't believe that +6 mm is the limit in the 750 case.

We start running into clearance problems with the bottom crankcase from memory.
Some of the pics I'm trying to sort out for Alex.
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