Topic: CB750 carb question

[lucky]

I have a 1978 CB750 and the carb slide needles only have one position. So if I want to raise the needle can I just use a 0.10 shim to raise the needle?

I am installing pod filters.
It is a stock engine with 4 into one header with muffler from Cycle X.
Mainjets increased from 110 to 120.

Will I even need to raise the needle?

I know someone on this forum has been through all this.
I mean com'n in 33 years of tuning it should have been worked out already.

[cougar]

Hey lucky; I have a "76 cb750SOHC with a Hondamatic 4>1 header w/2 1/2" outlet w/homemade muffler (baffle), breadbox air filter and stock (I think) motor. I run round tops on mine with 120 mains. I was running Rich until I dropped my needle Down 1 groove (moving clip up 1 position). I'ld say that you will be close on the current setting. Most folks here will probably tell you to do plug chops which I won't go into. See how it runs where it's currently and go from there.   ...cougar...

[Bill/BentON Racing]

You can use a shim;a points washer works well.You didn't say mm or in.! ;)Bill

[lucky]

You can use a shim;a points washer works well.You didn't say mm or in.! ;)Bill

Thanks Cougar for offering your experience.
That was .010 thousandths. After all we ARE in the USA.
When someone gives me mm then I have to convert it so I can visualize what we are taking about. LOL

[lucky]

Hey lucky; I have a "76 cb750SOHC with a Hondamatic 4>1 header w/2 1/2" outlet w/homemade muffler (baffle), breadbox air filter and stock (I think) motor. I run round tops on mine with 120 mains. I was running Rich until I dropped my needle Down 1 groove (moving clip up 1 position). I'ld say that you will be close on the current setting. Most folks here will probably tell you to do plug chops which I won't go into. See how it runs where it's currently and go from there.   ...cougar...

Yes I have heard this new term "plug chops" and I know what it is.
Plug chops are for WOT and most of us do not ride around with WOT very often. Mid range is more of a concern to me, and the transistions.
I am 62 and I had my first job in a Honda dealer when I was 16 .
But I also know if at WOT it keeps accelerating it is ok, and if it hits a flat spot it needs richening.

I don't like the idea of taking a plug out of the engine before it has cooled down. It can strip the threads unless it has anti seize on the threads.

[lucky]

I guess this all brings up the question, how many of you have had to use shims to get these 1978 carbs to work right with pods? Anybody?

Cycle X even recommends turning the bottom of the slides to richen up the midrange even more.

[754]

I might have a set of slides and  ajusta-needles from a 77 to sell...

[cougar]

lucky; I meant no disrespect. Maybe I should have read your bio before posting a responce.    ...cougar...                          Sidenote>  Just looked at your profile and no mention of your previous experience, so I'ld have still made the same statement. A lot of folks at at another site specifically for the cb750 SOHC Honda would suggest plug chops for all throttle settings so the mixture could be lined out at all throttle positions. And yes I'm not partial to pulling a plug from a hot head, that's why I don't do plug chops even though I do use anti seize on my plugs. I tune mine by feel and logic.

[scottly]

Yes I have heard this new term "plug chops" and I know what it is.
Plug chops are for WOT and most of us do not ride around with WOT very often. Mid range is more of a concern to me, and the transistions.
I am 62 and I had my first job in a Honda dealer when I was 16 .

Lucky, you sure ask a lot of newbie questions for someone with 46 years of Honda experience...

[Sam Green Racing]

Yes I have heard this new term "plug chops" and I know what it is.
Plug chops are for WOT and most of us do not ride around with WOT very often. Mid range is more of a concern to me, and the transistions.
I am 62 and I had my first job in a Honda dealer when I was 16 .

Lucky, you sure ask a lot of newbie questions for someone with 46 years of Honda experience...

Agreed Scottly,  and he sure likes posting in the wrong forum

Lucky, please read this. http://forums.sohc4.net/index.php?topic=59303.0

Sam.

[lucky]

Yes I have heard this new term "plug chops" and I know what it is.
Plug chops are for WOT and most of us do not ride around with WOT very often. Mid range is more of a concern to me, and the transistions.
I am 62 and I had my first job in a Honda dealer when I was 16 .

Lucky, you sure ask a lot of newbie questions for someone with 46 years of Honda experience...

Just trying to save myself a lot of work.
I know this has all been worked out.
I also help others save a lot of time by offering my advice.
I am  a certified welder and welding inspector,former jet engine mechanic and worked in motorcycle shops for many years.

I do appreciate the time saving information.

[lucky]

Yes I have heard this new term "plug chops" and I know what it is.
Plug chops are for WOT and most of us do not ride around with WOT very often. Mid range is more of a concern to me, and the transistions.
I am 62 and I had my first job in a Honda dealer when I was 16 .

Lucky, you sure ask a lot of newbie questions for someone with 46 years of Honda experience...

Agreed Scottly,  and he sure likes posting in the wrong forum

Lucky, please read this. http://forums.sohc4.net/index.php?topic=59303.0

Sam.

I thought that since all of you are into high performance issues that you have already learned all of this "simple stuff".  I just thought why not ask experienced engine builders.

One of my last projects was converting a Kawasaki 1500 V twin to chain drive from shaft drive ,thereby eliminating 60 lbs!,. It took 3 years of work and development. I eliminated 9 parts in the output front drive section.
Finally went direct drive from the countershaft. I offered a drawing of the drive hub and instructions with email and phone support for $200.00 No one was willing to do the work to make the modification. No sales.

What I learned is that very few people are willing to do the work, and they just want to buy a bubble wrap package that installs in 15 minutes.

Right after I finished my project Kawasaki changed their 1700 to belt drive.
It saved them a lot of weight.

[Bill/BentON Racing]

Lucky,a 4 speed for the auto would sell,have 2 buyers lined up! Plugs store a lot of info,underside of piston talks also. ,with anti-seize should have no problems....don't get burned! Bill

[lucky]

The underside of a piston? Never heard much talk about that.
I did hear on person who investigated using the crankcase pressure from the pistons going downwards to turbo charge the engine.

A SAE paper was written on the subject, It was researched and found to have not enough of a beneficial effect to be worth while. Just as filling the holes in a two stroke crank was found to be useless.