Honda CB550 four.. single carb.

Hurco550

Hurco550

Keep er' Between the Ditches
DTT SUPPORTER
DTT BOTM WINNER
Good morning ladies and gentlemen. I have yet another question for you wizards of the two wheeled world. I was wondering if you could run a cb550, with a custom intake manifold off of a single carb. I have done some research on here and found someone asking a similar question some time back (around 2010) and there wasn't much feedback on the issue other than high R.P.M. limitations. Has anyone done it or seen it done in anything other than a show bike? It just seems like it could be a rather cool mod, and would be perhaps less hassle once completed due to only tuning one carburetor. Just a thought. If its a stupid one just let me know. It wouldn't be the first one I had, and I can guarantee it wont be the last... thanks guys!
 
You could, but it probably wouldn't be a very good idea. What you gain in ease of tuning, you'd definitely lose in control. It would have to be one heck of a manifold design to ensure the each cylinder was getting the appropriate amount of fuel.
 
That is true, the tubes would all have to be the same length and everything right? and PVC pipe might not hold up to the fuel =P just kidding... I have been researching and haven't found many people with an inline four that have done it successfully
 
That's kinda the thing... it's not strictly an issue of same length. In some cases, depending on the bends that are made, you'll actually want uneven lengths. It's definitely not a simple endeavor if you want it running well.
 
I have seen the kits in the past to convert them to just dual carbs. have you had any experience with that? Maybe I am over thinking it and should just run the original 4 carbs.... I do want it to run well, kinda the point of a motorcycle right?
 
A lot of folks, even guys who've been around motorsports for a while, forget that bikes aren't cars. It's not uncommon (mostly in older models, but bear with me) for cars to use single point fuel injection or a single carb for multiple cylinders. But a car is a different beast.

Take the 5.0L V8 made by GM in the mid 80s... It had about 160 hp. That works out to 32 ponies per liter. The CB550 puts out 50hp, so that's 91 horse power per liter.

These two engines are in very different states of tune and I can definitely tell you which of the two would be more forgiving for fueling issues (hint: it's not the air cooled one). There is a definite reason Honda went with four individual throttle bodies and GM went with one.
 
IF you were to go with a single carb on an inline four, I would imagine that different length intake tracts would be necessary. Kinda like the old lakes header style exhaust you see on a lot of hot rods. Essentially you would end up with an intake manifold looking like the example below, and with a carb mounted to one end. The exact math to figure how long (or how proportionally long) your intake tubes need to be, however, is well beyond my pay grade ;D Also, Sonreir mentioned above the fact that many cars use single point fueling, while most bikes do not. The simple fact is a problem with configuration. It's much easier to work out intake tube lengths when you have a centrally located fueling unit (such as a single carb sitting on top of a V8). However, the space restrictions on a motorcycle dictate that the carb would likely have to be mounted off the side, which leads to the issue of different tube lengths for each cylinder.

221211.jpg
 
Sonreir said:
A lot of folks, even guys who've been around motorsports for a while, forget that bikes aren't cars. It's not uncommon (mostly in older models, but bear with me) for cars to use single point fuel injection or a single carb for multiple cylinders. But a car is a different beast.

Take the 5.0L V8 made by GM in the mid 80s... It had about 160 hp. That works out to 32 ponies per liter. The CB550 puts out 50hp, so that's 91 horse power per liter.

These two engines are in very different states of tune and I can definitely tell you which of the two would be more forgiving for fueling issues (hint: it's not the air cooled one). There is a definite reason Honda went with four individual throttle bodies and GM went with one.
Click to expand...

Well I am glad you made that point because that was exactly what I was thinking. I was thinking actually about the old 8n tractor sitting out back with 4 cylinders and 1 carb. Now that said I do realize that performance between a 1940's tractor and a street bike are two different things, but I was more thinking of concept. Thanks for hashing that out for me, and I am guessing ill just stick with the 4 carbs. In the end if it were a good mod to do, more ppl would probably have done it by now.
 
coyote13 said:
IF you were to go with a single carb on an inline four, I would imagine that different length intake tracts would be necessary. Kinda like the old lakes header style exhaust you see on a lot of hot rods. Essentially you would end up with an intake manifold looking like the example below, and with a carb mounted to one end. The exact math to figure how long (or how proportionally long) your intake tubes need to be, however, is well beyond my pay grade ;D Also, Sonreir mentioned above the fact that many cars use single point fueling, while most bikes do not. The simple fact is a problem with configuration. It's much easier to work out intake tube lengths when you have a centrally located fueling unit (such as a single carb sitting on top of a V8). However, the space restrictions on a motorcycle dictate that the carb would likely have to be mounted off the side, which leads to the issue of different tube lengths for each cylinder.

221211.jpg
Click to expand...

Guess I hadn't even thought of that style... I had in my mind a carb in the middle with the tubes fanning out..
 
hurco550 said:
I have seen the kits in the past to convert them to just dual carbs. have you had any experience with that? Maybe I am over thinking it and should just run the original 4 carbs.... I do want it to run well, kinda the point of a motorcycle right?
Click to expand...


I hear this come up every now and then, and every once in a while someone claims to have made the perfect adaptation, but... not so much. If conversion kits were out there, or it was easy to do and provided some kind of advantage, it would be done and more popular and an easy mod and everyone would be happy and life would be flowers and unicorns. And racers would run them.

Learning the four carbs on your 550 is worth doing. It's not that hard. Buy a proper sync tool (I do not recommend the Motion Pro -- blue liquid ones, they're terrible). Once you get your carbs dialed in you can leave em alone for ages depending on how often and how much and how you ride.
 
carnivorous chicken said:
I hear this come up every now and then, and every once in a while someone claims to have made the perfect adaptation, but... not so much. If conversion kits were out there, or it was easy to do and provided some kind of advantage, it would be done and more popular and an easy mod and everyone would be happy and life would be flowers and unicorns. And racers would run them.

Learning the four carbs on your 550 is worth doing. It's not that hard. Buy a proper sync tool (I do not recommend the Motion Pro -- blue liquid ones, they're terrible). Once you get your carbs dialed in you can leave em alone for ages depending on how often and how much and how you ride.
Click to expand...

I think that is a valid point that I should have thought of sooner as far as if it was a good option everyone would do it. I think the "black magic" of carbs kinda gets to me lol I am a two stroke guy and those carbs never scared me to much, but this whole world of 4 cycles is a new animal.

What carb sinc tool would you reccomend? I always see the generic ones for sale around like in the link below. Are these worth getting, or are they the ones your saying to stay away from?

http://www.ebay.com/itm/like/380985091328?lpid=82&chn=ps
 
I use a mercury manometer, not vacuum gauges. Some people prefer one over the other (ease of use vs accuracy), but I like what I've got. The mercury ones aren't available everywhere from what I know, and I actually got mine in a kind of under-the-table deal. Had it for years though, works great, never had a problem (including what I hear/read elsewhere, namely mercury getting sucked into one's carbs).
 
Check out turbo kits for the cb750 for some single carb ideas but of course the turbo itself changes everything.

There are a few 2 carb setups which might be the ticket. Again look to CB750 bits for inspiration.
 
Does anyone have a picture of a single carb 4 bike? Its a cool idea and I'm curious what this would look like on the bike.
 
i have a single on one of my cb750dohc when it warms up a bit i will go see if i can get the side covers off to take a pic
 
Tim said:
Check out turbo kits for the cb750 for some single carb ideas but of course the turbo itself changes everything.

There are a few 2 carb setups which might be the ticket. Again look to CB750 bits for inspiration.
Click to expand...

OOOOOO turbo. Dangit Tim, i dont need that floating around in my head too!.. AHHHH ;)
 
cxman said:
i have a single on one of my cb750dohc when it warms up a bit i will go see if i can get the side covers off to take a pic
Click to expand...

Yeah id be interested to see it too =)
 
hurco550 said:
Yeah id be interested to see it too =)
Click to expand...
trying to put a single carb on a 4 cylinder machine is a fool's game dude, there is nothing wrong with the stock carbs if you can't tune the bike with stock carbs, which is actually very easy to do, what makes you think you could with 1 ?
1 carb will never work RIGHT on the 550 4 the motor..it is cammed totally wrong for a single carb,you would need a cam that basically cuts the horsepower by 2/3rds or more , moving the peak down to 3600 rpm's like an industrial power unit
 
well since the experts have spoken i dont need to go take pics lol

how ever not to worry info on new single carb kits will be seen in abundance buy several manufacturers this year

that are centered in new manifold ideas and rotate around mikunis new hsr pumper 4 stroke specific carbs

i run a hsr42 on my 750
 
cxman said:
well since the experts have spoken i dont need to go take pics lol

how ever not to worry info on new single carb kits will be seen in abundance buy several manufacturers this year

that are centered in new manifold ideas and rotate around mikunis new hsr pumper 4 stroke specific carbs

i run a hsr42 on my 750
Click to expand...

but you have the knowledge,skill, time and ability to make it work, run well even if at a loss of some top-end power
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light
    • www.jadusmotorcycleparts.com
    www.lostapostle.ca/
    www.sparckmoto.com

    Spread the Love

    Back
    Top Bottom