one carb vs 4 carbs

i was thinking of switching to one carb, and making a manifold for the 4-1 intake setup. with running one carb, instead of the 4, what are the pros and cons of that? does performance suffer? im very curious if its even worth it. for now ill run n/a. thanks a lot!

dont have the answer but had the same question .. thanks for asking im intrested in that aswell

dont have the answer but had the same question .. thanks for asking im intrested in that aswell

freebyrd24 wrote:

i was thinking of switching to one carb, and making a manifold for the 4-1 intake setup. with running one carb, instead of the 4, what are the pros and cons of that? does performance suffer? im very curious if its even worth it. for now ill run n/a. thanks a lot!

Pros = one carb to adjust

Cons = performance hit, fabricating manifold, it will cost you more to go this route than to straighten out a set of stock carbs.

The ideal setup is a carb / throttle body & injector for each individual cylinder. That's how they came from the factory. They were / are performance designed engines.

Can it be done? Certainly it can. Ask yourself one question though. If it were better that way, wouldn't the factory have done that?

You will experience a decrease in performance. HP, fuel mileage, and throttle response. The area from the carb to the intake valve is called the intake runner, and it is a tuned component of the engine. Changing that will change your torque/HP curve. Long, narrow runners are good for low end torque. Short, fat runners are good for high rpm power. Long runners also degrade throttle response, as it takes longer for the air/fuel mixture reaching the combustion chamber to change due to a throttle input. Also, the fuel gets atomized in the carb. We all know that. But after getting atomized, the fuel droplets will start joining and forming larger droplets. The longer the intake runner, the more this happens. This is not good. The more this happens, the less complete the combustion, which is why HP and mileage would suffer. This is one area where fuel injection is vastly superior, since the injectors usually spray the fuel directly into the intake port. And then there's the manifold design. You'd need to design a manifold with equal length runners to each cylinder, and ensure that the flow is equal to each cylinder. There are few advantages and many disadvantages to going to a single carb. And I haven't even addressed all the testing required to get is running decent. I wouldn't do it.

Milkman did just that.
He has one carb on his 650. Been a few years now I think.

Here's a pic of his set up with seat!

Hey, Bemoore is shooting you a straight shot, so heed his words. That being said, you have to decide "what is My Goal" in this endevor. If your goal is more torque and less performance so you can use your motor for a sawmill power plant, thats a good reason to go with 1 carb and long intake throats. If its performance, leave it alone. Just look at how the engine has evolved over the past 100 years and you will have your answer. Just remember to ask the question "what is my goal". Joe

Post edited by: jaguar, at: 2007/11/12 09:26

Each cylinder is unique in managing its workload, due to differences in such variables as compression ratio, valve clearances, etc.

Having a separate carb for each cylinder allows each cylinder to be tuned for maximum efficiency, basically by allowing an individual fuel mixture tuning of the carb for that particular cylinder. Which coincidentally allows compensation for the vagaries among carbs.

Synching provides more equal (smoother) performance among the cylinders at lower rpm by regulating and equalizing the venturi vacuums among the cylinders.

With only a single carb serving all four cylinders, each cylinder is a slave to the single carb settings, regardless of whether the particular cylinder would individually perform better with a different carb setting.

So in a perfect world where each and every cylinder was operating with exactly the same efficiency, a single carb could be okay because the exact same carb tuning would apply to every cylinder.

At least that's my understanding.

Mine works fine for my needs. I gained a lot of low end torgue. I might have lost some on the top end but I have no clue because I don't ride it for speed. I did do 105, at least by the speedometer reading out on Rt. 95 for a couple miles and it would still accelerate quite hard.
I was told that it wouldn't work, so me being the anti-nay-sayer that I am had to prove them wrong. It starts easier, it's not near as cold blooded as it was.
Like I said it works well for me.
And maintenance is a breeze, one idle screw, one jet to adjust, and it only has one jet and the cold idle enrichment system. all I have to do is top off the dashpot oil occasional.
I did change from a carb that you needed to use an allen wrench thru the top to adjust the needle to an older one that you adjust the jet from the bottom.
It still mounts into the rubber manifolds like the mikunis did too.
And I've only got to buy one 23 buckazoid kit to rebuild it.
Ride safe

The Milkman wrote:

...And maintenance is a breeze, especially with self-synching....

:woohoo: Just teasing! :laugh:

You Go, Milkman!

Milkman, can I get you to come over and do some plumbing for me?
Aw hell, you probably heard all of the plumbing jokes by now... :laugh:

Nice job!

Post edited by: loudhvx, at: 2007/11/12 13:09