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Author Topic: 78K Big Bore Street/Track build  (Read 1869 times)

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Offline afkrejci90

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78K Big Bore Street/Track build
« on: February 11, 2016, 07:22:28 PM »
As this has gone from the typical restoration to a hi-po build, I figured it was time to start a thread in this section to document this build.  Starting with a 1978K CB750, the plan became to build a powerful bike for the strip and the occasional cruise.  Here's a list of what is going into this build:
  • Custom JE 1000cc 12.5:1 CR piston kit
  • DP327 cam
  • Carrillo H-beam connecting rods
  • Kibblewhite +2mm 5mm conversion kit
  • Mike Rieck Stage IV porting
  • APE lightened crank
  • APE back cut super sport transmission
  • Weber 40 DCOE carburetors
  • Nitrous Express wet kit
  • Dyna 2000 Ignition

The way the bike looked when I bought it and right before tear down.








Starting on the engine dis-assembly.




Split the cases.


Internals looked to be in good shape.


Certainly had an oil leak.


The head before Mike Rieck worked his magic on it.


Porting finished and ready to install the valves.










Valve kit installed.


CC'd the chambers and made molds for the custom pistons.






APE removed, bored, and installed new sleeves along with lightening and balancing the crankshaft.






Working on a way to mount the Weber's to the bike.  Designed a manifold to adapt the Weber's and also include ports for the nitrous foggers.  Just waiting on the parts to be machined.
« Last Edit: February 12, 2016, 12:22:10 PM by afkrejci90 »
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'80 CB750C - Sold
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Online madmtnmotors

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Re: 78K Big Bore Street/Track build
« Reply #1 on: February 11, 2016, 07:51:29 PM »
Hot damn! Subscribed!  8)
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Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline dragracer

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Re: 78K Big Bore Street/Track build
« Reply #2 on: February 11, 2016, 08:53:56 PM »
This is going to be gooooooood!!!!
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 78K Big Bore Street/Track build
« Reply #3 on: February 11, 2016, 09:00:10 PM »
Subscribed also  :)

Hoping you might be willing to replicate some of those manifolds.
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As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline afkrejci90

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Re: 78K Big Bore Street/Track build
« Reply #4 on: February 11, 2016, 09:08:16 PM »
Quote from: Jerry Rxman Griffin aka MuthaF'er on February 11, 2016, 09:00:10 PM
Hoping you might be willing to replicate some of those manifolds.

It's in the works.  If I can't find a shop that can do it with a reasonable turn around or a realistic price, I'm going to be making these myself.
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'80 CB750C - Sold
'06 CBR600RR

Offline RAZZ

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Re: 78K Big Bore Street/Track build
« Reply #5 on: February 12, 2016, 02:50:52 AM »

Quote from: madmtnmotors on February 11, 2016, 07:51:29 PM
Hot damn! Subscribed!  8)

+1



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Offline Restoration Fan

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Re: 78K Big Bore Street/Track build
« Reply #6 on: February 12, 2016, 04:24:30 AM »
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Ron

Stella - Logan's Senior Project    78 750K http://forums.sohc4.net/index.php?topic=141761.0

Logan's Reward - CB500 and CB550 Cafes    http://forums.sohc4.net/index.php/topic,147787.0.html

Offline Bill/BentON Racing

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Re: 78K Big Bore Street/Track build
« Reply #7 on: February 12, 2016, 05:02:45 AM »
Nice, I see 100+ rwhp! 110? Great looking build! K.
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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Offline slikwilli420

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Re: 78K Big Bore Street/Track build
« Reply #8 on: February 12, 2016, 05:32:56 AM »
When I did my Weber manifold, since I didn't have access  to CNC equipment, I had the plate water jet cut and turned the 4 spigots on the lathe and had it welded up. I made a 3/4" steel plate to bolt the manifold to for welding so it didn't warp, and it worked like a charm. That much machining out of one billet is likely pretty expensive, but my way allowed for cost savings in materials and machine time.

Question about your motor build. Why go all the way with other parts and not go Stage 4 with the 5mm valve conversion?
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AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
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Offline afkrejci90

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Re: 78K Big Bore Street/Track build
« Reply #9 on: February 12, 2016, 10:09:47 AM »
Quote from: slikwilli420 on February 12, 2016, 05:32:56 AM
When I did my Weber manifold, since I didn't have access  to CNC equipment, I had the plate water jet cut and turned the 4 spigots on the lathe and had it welded up. I made a 3/4" steel plate to bolt the manifold to for welding so it didn't warp, and it worked like a charm. That much machining out of one billet is likely pretty expensive, but my way allowed for cost savings in materials and machine time.

Question about your motor build. Why go all the way with other parts and not go Stage 4 with the 5mm valve conversion?
That is the way I planned on doing it.  Milling that all in one block would be complex and time consuming. 

I wasn't aware of the stage 4.  What is the difference between 3 and 4?

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Offline slikwilli420

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Re: 78K Big Bore Street/Track build
« Reply #10 on: February 12, 2016, 11:03:40 AM »
Seems to be the most economical way aside from casting. I'm looking forward to seeing yours come together, as well as getting mine finished and running.

That includes oversized valves as well as the conversion to 5mm stems. The stock ones are like 7mm but with better materials they can be thinner and still stronger than stock. Reach out to Mike Rieck if you want more detail.
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All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline afkrejci90

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Re: 78K Big Bore Street/Track build
« Reply #11 on: February 12, 2016, 11:28:29 AM »
Quote from: slikwilli420 on February 12, 2016, 11:03:40 AM

That includes oversized valves as well as the conversion to 5mm stems. The stock ones are like 7mm but with better materials they can be thinner and still stronger than stock. Reach out to Mike Rieck if you want more detail.

These are the oversized valves with 5mm stems.
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Offline MRieck

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Re: 78K Big Bore Street/Track build
« Reply #12 on: February 12, 2016, 12:03:57 PM »
Quote from: afkrejci90 on February 12, 2016, 11:28:29 AM
Quote from: slikwilli420 on February 12, 2016, 11:03:40 AM

That includes oversized valves as well as the conversion to 5mm stems. The stock ones are like 7mm but with better materials they can be thinner and still stronger than stock. Reach out to Mike Rieck if you want more detail.

These are the oversized valves with 5mm stems.
So it's Stage 4. ;D When did I do that head????
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Offline afkrejci90

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Re: 78K Big Bore Street/Track build
« Reply #13 on: February 12, 2016, 12:23:19 PM »
Quote from: MRieck on February 12, 2016, 12:03:57 PM
Quote from: afkrejci90 on February 12, 2016, 11:28:29 AM
Quote from: slikwilli420 on February 12, 2016, 11:03:40 AM

That includes oversized valves as well as the conversion to 5mm stems. The stock ones are like 7mm but with better materials they can be thinner and still stronger than stock. Reach out to Mike Rieck if you want more detail.

These are the oversized valves with 5mm stems.
So it's Stage 4. ;D When did I do that head????

I think it was spring of 2014.
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'78 CB750K http://forums.sohc4.net/index.php?topic=105327.0
'80 CB750C - Sold
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Offline BPellerine

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Re: 78K Big Bore Street/Track build
« Reply #14 on: February 12, 2016, 12:28:02 PM »
cool build,webers with nitrious!wow.billp
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