Author Topic: Question for experts  (Read 1822 times)

0 Members and 1 Guest are viewing this topic.

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Question for experts
« on: June 21, 2012, 06:09:47 pm »
I am about to take the carbs off of my CB750K 1978. It is running perfect but I just do not like the carbs.
I was going to put my 1969 carbs on instead. I like how easy they are to tune. Like changing needles etc.,.

Is there anything I should know before I bark up the wrong tree?


Right now i have the 78 carbs.
non adjustable needle.
#120 main jets.
#42 idle jets.
Mixture screw out 1 turn.
Cycle-X 4 into 2 into 1 exhaust.
Stock intake and stock air filter.

Good throttle response ,starts easy .
Plugs look right.
In top gear it will just keep accelerating no problem.


Online CycleRanger

  • No comment about being an
  • Really Old Timer ...
  • *******
  • Posts: 5,359
  • Central Texas Shop Manual Advocate
Re: Question for experts
« Reply #1 on: June 21, 2012, 06:18:18 pm »
 ::)
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: Question for experts
« Reply #2 on: June 21, 2012, 06:34:56 pm »
::)

Is that some kind of !@@#!$!%#$ answer?
You are too high and mighty to answer or you just have never worked with the early style carbs?

Here this is for you ::)

Offline CBJoe

  • Master
  • *****
  • Posts: 1,974
Re: Question for experts
« Reply #3 on: June 21, 2012, 06:58:35 pm »
::)

Is that some kind of !@@#!$!%#$ answer?
You are too high and mighty to answer or you just have never worked with the early style carbs?

Here this is for you ::)

I think in general it was a satirical ideal associated with asking for general carb jetting advice in the Hi-Po area. 

But maybe I shouldn't answer this as I'm likely no more educated than you are on CB750 Carb stuffs... ::)

Or we could discuss the existential existence of the smiley-face eye roll.... but maybe not as I don't seem to be able to keep my bikes running.  So in the end this is probably all my fault. Not...


Cheers, Joe
 
'07 Bonneville Black
'15 Moto Guzzi California 1400
CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
'66 CM91 (C90'ish)

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: Question for experts
« Reply #4 on: June 21, 2012, 08:44:07 pm »
I was asking this question on this forum because I do NOT need general jetting information.. I can already do that myself.

I thought that the people on this forum had RACING experience and one of you may have even used the 1969 carbs on a later model. I wanted to know your experience.
Last week I came across a thread where a guy bough a drag racing 1978 CB750 that did have CB750 1969 carbs already on it. But that guy knew nothing and was changing out all the great parts on that bike.

I guess none of you know. thats all.

Offline scottly

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 16,162
  • Humboldt, AZ
Re: Question for experts
« Reply #5 on: June 21, 2012, 09:24:41 pm »
I am about to take the carbs off of my CB750K 1978. It is running perfect but I just do not like the carbs.

If it is running perfect, then you are done with tuning anyway. Why are you taking a step backward? As far as asking the experts, if you don't know what you are talking about, please refrain in the future from giving out erroneous advice on tuning, trouble-shooting, and terminology as you have done so many times in the past... ;)
You built a nice looking bike, BTW. ;D
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline Stev-o

  • Ain't no
  • Really Old Timer ...
  • *******
  • Posts: 34,109
  • Central Texas
Re: Question for experts
« Reply #6 on: June 21, 2012, 09:49:29 pm »
I'm no expert but the last thing I would ever do to my K8 is change the carbs!  Two flicks of the throttle, pull on the choke, push the button and it starts right up every time.
Don't care for the cable choke control, though, lever is better.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Sam Green Racing

  • Moderator
  • Really Old Timer ...
  • *****
  • Posts: 16,068
  • I REALLY? hate black rims.
Re: Question for experts
« Reply #7 on: June 22, 2012, 05:40:22 am »
Let's try to keep it nice gentlemen ;D ;D
lucky posted in the wrong forum and worded the title wrong.
Perhaps had he asked for someone who had done this before and were there any pitfalls, it might have been clearer.
My own take on this is, (not an expert) why bother about notches on a needle when the weather can cause the jetting to be out by as much as a couple of jet sizes at any time of the day? One just needs to find the sweet spot in the carburration which it seems like lucky has already done.

Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: Question for experts
« Reply #8 on: June 22, 2012, 12:03:14 pm »
Here is something you may have been able to tell me.
The 1978 Rubber mount boots fit the 1969 carbs.
They were about .060 loose but I did the simple thing and just tightened up the boot. It worked!


Perhaps one of you knew that already and could have advised me.
I do like not having a choke cable.
I can change the jets now and the needles without even taking the carbs off!

I will see how they perform.





Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: Question for experts
« Reply #9 on: June 22, 2012, 12:04:37 pm »
I'm no expert but the last thing I would ever do to my K8 is change the carbs!  Two flicks of the throttle, pull on the choke, push the button and it starts right up every time.
Don't care for the cable choke control, though, lever is better.

I am glad you like your K8 carbs Steve-O.