Author Topic: Figuring Out My Carb  (Read 1418 times)

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Offline Ellz10

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Figuring Out My Carb
« on: August 29, 2021, 03:19:00 PM »
Quick question. I've tried looking up what type of carb I have and the size of it, but to no avail. I'm particularly interested in what the size of it is. Can I use a telescopic cylinder bore to figure it out or can I find everything I need to know out from the markings on the carb itself. If so, where would I look, because I've tried googling what I found and nothing popped up. Any help would be appreciated.

- Z
Thankful for everyone on this forum. Grateful to continue to learn so much.



'77 K7 - http://forums.sohc4.net/index.php/topic,193043.msg2251436/topicseen.html#new

Offline goodtryer

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Re: Figuring Out My Carb
« Reply #1 on: August 29, 2021, 04:26:03 PM »
What year and what bike?

There will be some markings on the carbs. Usually on the sides just above the float bowl or on the top of the bracket that holds the 4 carbs together.

Typically something like PD41 or 42. Or 022, 069, 087. Might not have those exactly correct but you get the idea. You’ll recognize it when you see it.
"Tolerance will reach such a level that intelligent people will be banned from thinking so as not to offend the imbeciles."
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1977 CB550K
1978 CB750K
1973 CB500K

Offline ekpent

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Re: Figuring Out My Carb
« Reply #2 on: August 29, 2021, 06:06:33 PM »
 Be nice if you could post a picture along with your bike info.

Online newday777

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Re: Figuring Out My Carb
« Reply #3 on: August 30, 2021, 02:17:37 AM »
Quick question. I've tried looking up what type of carb I have and the size of it, but to no avail. I'm particularly interested in what the size of it is. Can I use a telescopic cylinder bore to figure it out or can I find everything I need to know out from the markings on the carb itself. If so, where would I look, because I've tried googling what I found and nothing popped up. Any help would be appreciated.

- Z

As a parts manager and you came in with that question and saying 'carb' and 'it' to me, that makes me think and ask you Z, are running a single carb and what bike????? Aftermarket carb or???????
Not enough information from you doesn't get you answered until you fill in the gaps......
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline robvangulik

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Re: Figuring Out My Carb
« Reply #4 on: August 30, 2021, 03:55:06 AM »
All his previous questions concerned what used to be a 750k7, so PD carbs should be right. But who knows what's left of it by now ;)

Offline Ellz10

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Re: Figuring Out My Carb
« Reply #5 on: August 30, 2021, 08:24:09 AM »
What year and what bike?

There will be some markings on the carbs. Usually on the sides just above the float bowl or on the top of the bracket that holds the 4 carbs together.

Typically something like PD41 or 42. Or 022, 069, 087. Might not have those exactly correct but you get the idea. You’ll recognize it when you see it.

My apologies, I wasn't even thinking when I posted.

Bike is a 1977 Honda CB750K


I think it might be an aftermarket carb, but I'm not 100% sure.
Quick question. I've tried looking up what type of carb I have and the size of it, but to no avail. I'm particularly interested in what the size of it is. Can I use a telescopic cylinder bore to figure it out or can I find everything I need to know out from the markings on the carb itself. If so, where would I look, because I've tried googling what I found and nothing popped up. Any help would be appreciated.

- Z

As a parts manager and you came in with that question and saying 'carb' and 'it' to me, that makes me think and ask you Z, are running a single carb and what bike????? Aftermarket carb or???????
Not enough information from you doesn't get you answered until you fill in the gaps......
Thankful for everyone on this forum. Grateful to continue to learn so much.



'77 K7 - http://forums.sohc4.net/index.php/topic,193043.msg2251436/topicseen.html#new

Offline bryanj

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Re: Figuring Out My Carb
« Reply #6 on: August 30, 2021, 09:37:30 AM »
 ;)they aint original to that bike, there is a flat "pad" just above the brass vaccum takeoff plug in pic 2 on that will be some letters/numbers what are they and be precise
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Bankerdanny

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Re: Figuring Out My Carb
« Reply #7 on: August 30, 2021, 10:57:14 AM »
Those are 'round top' carbs from a 71-76 750K or 75-76 750F. Functionally those are all the same. The numbers stamped on the holder will tell you what year and model so you know what jet sizes and needle numbers they came with originally, but the jets and needles interchange.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Online newday777

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Re: Figuring Out My Carb
« Reply #8 on: August 30, 2021, 05:30:07 PM »
Well your carbs are definitely Honda but not from a 1977. As Danny said 71-76....so are you sure you have a 77 and not a 76? What year model does the vin tag show on the steering neck?

Those carbs are 28mm
 
To help identify your bike.....
This is a 1976 K6 specs and picture.
https://bikez.com/motorcycles/honda_cb_750_f_1976.php

https://www.motorcyclespecs.co.za/model/Honda/honda_cb750k_76.html



1977 cb750 k7 specs and picture

https://www.autoevolution.com/moto/honda-cb-750-four-k7-1977.html
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline Ellz10

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Re: Figuring Out My Carb
« Reply #9 on: August 31, 2021, 09:50:14 PM »
Those are 'round top' carbs from a 71-76 750K or 75-76 750F. Functionally those are all the same. The numbers stamped on the holder will tell you what year and model so you know what jet sizes and needle numbers they came with originally, but the jets and needles interchange.

That's what I was curious about. Good to know. The guy that did work on it back in '09 (last time it was on the road) said he bought it brand new. Now I'm doubting alot of things about him and what he did.
Well your carbs are definitely Honda but not from a 1977. As Danny said 71-76....so are you sure you have a 77 and not a 76? What year model does the vin tag show on the steering neck?

Those carbs are 28mm
 
To help identify your bike.....
This is a 1976 K6 specs and picture.
https://bikez.com/motorcycles/honda_cb_750_f_1976.php

https://www.motorcyclespecs.co.za/model/Honda/honda_cb750k_76.html



1977 cb750 k7 specs and picture

https://www.autoevolution.com/moto/honda-cb-750-four-k7-1977.html

100% sure it's a '77. The guy who worked on it last was a bit lackluster in a few departments.

I am glad to find out the size, for now I know I need to buy something else. I'm thinking a Mikuni 32mm or so if they make one for this bike.

Any suggestions on what to buy fellas? Obviously want to stick around 32 or so.

Bike is a '77 as mentioned.

Work that has been done is:

Carillo Connecting Rods
WiseCo Pistons 11.5 (836)
Super Studs (Cylinder Studs)
CX-11 Cam
New Cush Drive Bearing
Crankshaft Lightened and Balanced
Super Gasket Set (65mm)
Treated Main Bearings
Treated Rod Bearings
Adjustable Cam Sprocket Kit
Super Flow Valve Set
Cast Guides
Spring Set
Primary Chains
Tsubaki Cam Chains (Cryo)
Primary Chain Tensioner
Deluxe Bore & Hone .65 Over
Alternator Lightened and Balanced
Undercut Transmission
Cush Drive Rebuild
Combustion Chamber Blending Modification
Head Option #2 (Both sides of head surfaced, guides replaced and reamed, valve job)
Line Lap Engine Cases
Refurbish Electric Starter
Rebuild Output Shaft
Thankful for everyone on this forum. Grateful to continue to learn so much.



'77 K7 - http://forums.sohc4.net/index.php/topic,193043.msg2251436/topicseen.html#new

Offline Ellz10

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Re: Figuring Out My Carb
« Reply #10 on: September 01, 2021, 12:28:57 PM »
I've seriously contemplated going with the Keihin CR31 setup. All around it seems as though it would serve me well in my setup. Thoughts?
Thankful for everyone on this forum. Grateful to continue to learn so much.



'77 K7 - http://forums.sohc4.net/index.php/topic,193043.msg2251436/topicseen.html#new

Online newday777

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Re: Figuring Out My Carb
« Reply #11 on: September 01, 2021, 05:37:15 PM »
I've seriously contemplated going with the Keihin CR31 setup. All around it seems as though it would serve me well in my setup. Thoughts?

There is a fair amount already posted on them.

http://forums.sohc4.net/index.php?topic=40413.0

Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline Ellz10

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Re: Figuring Out My Carb
« Reply #12 on: September 02, 2021, 12:31:00 PM »
I've seriously contemplated going with the Keihin CR31 setup. All around it seems as though it would serve me well in my setup. Thoughts?

There is a fair amount already posted on them.

http://forums.sohc4.net/index.php?topic=40413.0

I read that entire thread and now I'm conflicted as to whether or not to buy the CR29 or the CR31. I mean as I mentioned, the motor is modified so I'm not sure if it's modified ENOUGH to be able to run smoothly with the CR31.... thoughts?
Thankful for everyone on this forum. Grateful to continue to learn so much.



'77 K7 - http://forums.sohc4.net/index.php/topic,193043.msg2251436/topicseen.html#new

Online newday777

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Re: Figuring Out My Carb
« Reply #13 on: September 03, 2021, 04:23:16 AM »
I've seriously contemplated going with the Keihin CR31 setup. All around it seems as though it would serve me well in my setup. Thoughts?

There is a fair amount already posted on them.

http://forums.sohc4.net/index.php?topic=40413.0

I read that entire thread and now I'm conflicted as to whether or not to buy the CR29 or the CR31. I mean as I mentioned, the motor is modified so I'm not sure if it's modified ENOUGH to be able to run smoothly with the CR31.... thoughts?

I have not run either. I kept the stock 76 carbs on my 811(then later 836 bore), 3/4 race cam, 3 angle valve cuts and polished ports which did fine for my street riding and cross country runs back in the 70s.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A