Author Topic: CB750 40 Special (finally done)  (Read 36263 times)

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Offline B.O.X.N.I.F.E.

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Re: CB750 40 Special (finally done)
« Reply #100 on: May 15, 2011, 11:02:06 AM »
quality build, congratulations
1974 CB550

32 days and 5,536 miles on a CB550...

http://kerncountykid.blogspot.com/

and a couple years later, 38 days and 9,102 miles...

Forever West

... and all of it in a 4 mintue video

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Offline bjatwood

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Re: CB750 40 Special (finally done)
« Reply #101 on: May 19, 2011, 05:37:50 AM »
(well only that my face hurts from smilling so much when riding it)

You sure that's not from the bugs hittin your teeth while riding?!? LOL
Brian
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I believe that the Finest things are the most thoughtfully made, not the most expensive!
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Offline greenjeans

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Re: CB750 40 Special (finally done)
« Reply #102 on: May 19, 2011, 05:52:07 AM »
That turned out fantastic !    Good looking all around.  Well done.
Yep, I'm the kid that figured out how to put things back together...eventually.

Offline MilehighCB

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Re: CB750 40 Special (finally done)
« Reply #103 on: May 19, 2011, 06:08:33 AM »
Great built and attention to detail!!!

Couple questions:

Where did you get the finned engine covers?

What is your carb set up?  Did you drill out the slow jets, what are you running for main jets?  Did you change jets from Pods to Stacks?  How is it running with the stacks, idle issues, flat spots etc?

Again great work!!

Offline mrrch

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Re: CB750 40 Special (finally done)
« Reply #104 on: May 19, 2011, 05:45:21 PM »
Finned covers came from ebay last year.
I went with the stacks because they look better(i'm being honest/ the pods were interfering with my choke)
I'm going to make some foam filters to slip over them soon and see how it runs.
I went up one size on the main jet and richened up the needle by lowering the clip, slow jets are stock(PD carbs with the accel pump)
So far so good, I have had to fine tune the fuel screws abit and fine tune my ignition timing (old Presolite electronic)
It's running great in my opinion but I only have about 160 km on it so far (taking it easy, checking things after every ride)
my build

1977 CB750K WITH 1976 CB750F ENGINE

Offline MilehighCB

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Re: CB750 40 Special (finally done)
« Reply #105 on: May 20, 2011, 04:22:42 PM »
Thanks for the info on the fins, they look great.

From the build info, it looks like you must have 77 carbs, if you were able to drop the clip, I assume you dropped it down from the center clip position.  (2nd from bottom now)?

When you say go up one jet size, meaning up from 110s (stock) to 120's?

Lastly, how do the stacks fit up for you?  They look great and I have been thinking about picking some up too.

All my guestions are because I am running a similar setup, however I drilled my slow jets and I am running 135 mains.  Thinking I am slghtly rich.
Thanks

Offline mrrch

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Re: CB750 40 Special (finally done)
« Reply #106 on: May 20, 2011, 05:27:01 PM »
Stacks fit great, the exact jetting specs are not in my head but I do have them written down (i'll post them up soon)
my build

1977 CB750K WITH 1976 CB750F ENGINE

Offline lucky

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Re: CB750 40 Special (finally done)
« Reply #107 on: April 12, 2012, 07:42:53 AM »
I ditched the pods and got velocity stacks from Steel Dragon Performance. Running good so far,no complaints(well only that my face hurts from smilling so much when riding it)

Great looking build!!!
You must have had to increase the jet sizes right?

Offline lucky

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Re: CB750 40 Special (finally done)
« Reply #108 on: April 12, 2012, 07:45:37 AM »
Thanks for the info on the fins, they look great.

From the build info, it looks like you must have 77 carbs, if you were able to drop the clip, I assume you dropped it down from the center clip position.  (2nd from bottom now)?

When you say go up one jet size, meaning up from 110s (stock) to 120's?

Lastly, how do the stacks fit up for you?  They look great and I have been thinking about picking some up too.

All my guestions are because I am running a similar setup, however I drilled my slow jets and I am running 135 mains.  Thinking I am slghtly rich.
Thanks

Go with 120 mains and a #45 idle jet.
Thats what will work.
IF they are 77 carbs the clip is not adjustable.

Offline lucky

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Re: CB750 40 Special
« Reply #109 on: April 24, 2012, 08:01:01 AM »
No I did not heat cure the engine parts in an oven. It has been very hot here so I left them outside in the sun for a few days to harden. The rubber pieces are there for vibration I think, I just painted over them.
Honda had some models with gold coloured cylinder heads (CB1100F maybe?) I like the look of the old Honda CR motocross bikes with gold FMF heads on them (that's what gave me the idea)
I hope to have the engine back in the frame later next week.

The rubber"dots" between cylinder fins was to reduce noise when cooling down.
On the 77-78's they did away with them,and they added more cooling fins to the engine cases and the oil filter housing.

Offline knowsnothing

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Re: CB750 40 Special
« Reply #110 on: April 24, 2012, 08:05:49 AM »
No I did not heat cure the engine parts in an oven. It has been very hot here so I left them outside in the sun for a few days to harden. The rubber pieces are there for vibration I think, I just painted over them.
Honda had some models with gold coloured cylinder heads (CB1100F maybe?) I like the look of the old Honda CR motocross bikes with gold FMF heads on them (that's what gave me the idea)
I hope to have the engine back in the frame later next week.

The rubber"dots" between cylinder fins was to reduce noise when cooling down.
On the 77-78's they did away with them,and they added more cooling fins to the engine cases and the oil filter housing.

Lucky I am not sure if that is correct.  If you are referring to the rubber pucks between the fins, all 3 of my 78's had them. 
1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline theofam

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Re: CB750 40 Special (finally done)
« Reply #111 on: April 26, 2012, 07:23:56 AM »
Lucky, knowsnothing is right, 78s had the white rubber pucks in the cylinder fins, including the little holes to accept the pucks' nipples for a tight fit.

Offline knowsnothing

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Re: CB750 40 Special (finally done)
« Reply #112 on: April 26, 2012, 12:07:54 PM »
Lucky, knowsnothing is right, 78s had the white rubber pucks in the cylinder fins, including the little holes to accept the pucks' nipples for a tight fit.

Yeah, they are a down right b*itch to get in or out.
1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline Stoli

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Re: CB750 40 Special (finally done)
« Reply #113 on: March 19, 2013, 09:13:14 AM »

Hey mrrch, couple of questions about your build. Hopefully you are still following this thread.

Where did you get that 3 piece exhaust hanger clamp that you show on page 4?

How much did you have to shim the steering column to avoid hitting the tank with the handle bars?

Where did you get those side covers?
My Project Threads:
Project #1 - http://forums.sohc4.net/index.php?topic=117106.0  First bike
Project #2 - http://forums.sohc4.net/index.php?topic=127364.0  Something different
Project #3 - http://forums.sohc4.net/index.php?topic=123831.0  Long and Low

Offline JC Blues

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Re: CB750 40 Special (finally done)
« Reply #114 on: March 19, 2013, 11:16:55 AM »
that is one slick looking machine!!!! great quality work!! i hope for mine to look like that one day :)

Offline mrrch

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Re: CB750 40 Special (finally done)
« Reply #115 on: March 19, 2013, 11:46:20 AM »
The frame clamp was just a universal clamp out of a cruiser catalogue, the side covers came from Frankenstuff here on the forums. I drilled & tapped the steering stops on the lower triple clamp to accept a small allen head screw to make them adjustable.
my build

1977 CB750K WITH 1976 CB750F ENGINE