Author Topic: 1972 CB750K2 - engine freshen up  (Read 9308 times)

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Offline SBR-CB400F

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #50 on: April 09, 2015, 05:00:24 AM »
Holiday pictures please HD.
It's on my to do list getting to tassie

Adam
1975 cb400f, 14.435 @ 89.01MPH at Willowbank Street Series 28 March 2015
1976 cb400f Nostalgia Drag Bike.
1.871 @ the 60'
8.632 @ 78.44 mph over the 1/8.
13.822 @ 91.91 mph over the 1/4
1977 cb750f2 Resto Project
1973 cb750k4 Chopper project
1971 cb750k1 Restoration Project
1975 cb750f1 Drag bike
1.549 @ 60'
4.425 @ 330'
6.895 @ 98.05MPH  1/8 mile
10.993 @ 116.76MPH  1/4 mile

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #51 on: May 03, 2015, 09:31:50 PM »
Back from probably the best holiday I've ever had, and trying to get my head around where I was up to with this engine.
So decided to jump in the deep end yesterday and do some porting on the head. I have to say that I have no flow bench and unfortunately do not have access to one, but have played a little with heads before.
Ideas have obviously come from others examples that I have been able to find photos of online, predominantly this has been Mike Riecks work, I claim in no way that anything I have done could be compared to his work, but I have gotten my hands dirty and given it a "red hot go".
The work I've done included removal of any casting marks/irregularities.
Removal of the guide bosses on the intakes.
Minimisation of the guide bosses on the exhausts.
Guides are to be tapered and installed later this week after I get to use a mates lathe.
Port floors have been left in a rounder shape and not flattened off as in some of Mike's heads, however all irregularities and transitions have been smoothed off.
Seats have been matched to ports.
Chambers have been deschrouded and I think still need a little work.

Anyhow on with the photos, any comments positive or negative appreciated.....as we all have things to learn.

The fun begins.




















Ciao

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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #52 on: May 03, 2015, 11:22:29 PM »
Installed the HD APE cylinder studs as well.


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« Last Edit: May 04, 2015, 02:59:25 AM by hotdog »
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #53 on: May 28, 2015, 01:42:27 AM »
Got some traction on the engine build today. Waiting for my flow bench, its in customs at the moment. So decided to build this thing as I need a ride besides my hard tail xs650, I have other heads I can play with after this one.

These will have to do for now...



Assembled ready for install.





Barrels on and prepping for head install...



0.030 mls gasket



Fum and games timing the camshaft.





Original Norris timing card that came with my cam.



Figures that I came up with after screwing around for a while...I'm calling it done.



All going well engine in frame tomorrow........

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« Last Edit: May 28, 2015, 01:45:30 AM by hotdog »
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #54 on: May 29, 2015, 03:59:21 AM »
Hopefully last post on this, Engine going in...spent more time positioning the carbs/air box than it took to install the engine.



Finished, runs well. Engine is tight and once it loosens up should be great. No oil leaks.....



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Offline andy750

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Re: 1972 CB750K2 - engine freshen up
« Reply #55 on: May 29, 2015, 07:55:46 AM »
Great write up and and very clear photos - any plans to get this dynoed? Id be very curious to see those results. Looking forward to the ride report!

cheers
Andy
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #56 on: May 30, 2015, 12:13:17 AM »
Thanks Andy, no dyno plans at this stage.
I do know I need to tweak the jetting as the midrange is a bit flat. Priority is to get some km's on the engine first and adjust jetting as I go. Might take a while as it looks like we will be looking at potential houses for a while.

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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up
« Reply #57 on: May 30, 2015, 02:02:51 AM »
Bike looks great Hotdog... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline MRieck

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Re: 1972 CB750K2 - engine freshen up
« Reply #58 on: May 30, 2015, 06:26:47 AM »
Here is a great set of carbide cutters for people with only a dremel tool. They have the 1/8" shank but can be ordered in 3" length. I have a set and they work well.
http://ccspecialtytool.com/carbide-cutters-18
Owner of the "Million Dollar CB"

Offline Old Scrambler

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Re: 1972 CB750K2 - engine freshen up
« Reply #59 on: May 30, 2015, 06:56:16 AM »
You do nice work, Mr. Hotdog ;)

Thanks for the cutter tip, Mike :) I just ordered a set for Dave Murre to keep him happy ;)
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #60 on: June 22, 2015, 07:59:20 PM »
Tuned and ready for riding....

https://youtu.be/2aoe6Yt6nCc

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« Last Edit: June 22, 2015, 08:37:47 PM by hotdog »
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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up
« Reply #61 on: June 22, 2015, 08:44:54 PM »
Sounds great Dale... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #62 on: June 22, 2015, 09:44:53 PM »
Just got back from a ride.
WOT roll-ons at 100kmh (65mph) there is some hesitation, I have jets on order and will change out the #110 mains for #115's and hopefully the lean spot will clear up.

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Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB750K2 - engine freshen up
« Reply #63 on: June 22, 2015, 09:56:12 PM »
Loved the sound of the video.  I cranked up the speakers and my cat went running out of the office!
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up
« Reply #64 on: July 25, 2015, 10:49:29 PM »
Couple of quick pics yesterday, wife wanted to try out the new camera.





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« Last Edit: August 05, 2015, 09:36:42 PM by hotdog »
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Offline flatlander

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Re: 1972 CB750K2 - engine freshen up
« Reply #65 on: July 26, 2015, 02:24:44 AM »
very nice pictures!

Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up
« Reply #66 on: July 26, 2015, 03:34:47 PM »
Looks great Dale... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB750K2 - engine freshen up
« Reply #67 on: July 26, 2015, 05:31:32 PM »
That K2 looks terrific.  Great job!  ;D
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline 70CB750

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Re: 1972 CB750K2 - engine freshen up
« Reply #68 on: July 27, 2015, 06:55:55 AM »
Beauty!

Couple of quick pics yesterday, wife wanted to try out the new camera.





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