KEIHIN Carb fed by fuel pump?

[myates92]

Has anyone ever seen or set up a set of KEIHIN CVK carbs to be fed by a fuel pump? I am using a 06 250 motor in an application where gravity feed isn't an option... Vacuum or Electric? What kind of pressure is running at the regulator?

[SibSerge]

The pressure at the float valve is easy to calculate. The top of the tank is roughly a foot over the carb inlet. Its 14psi to 33ft of elevation for water (gas is slightly lighter but not important here). So you have about 0.5psi at the carb inlet at its maximum. Much less than that when the tank is near empty.
You could install a small buffer tank above the carbs with a level switch that will turn the pump off when full. It will essentially convert the pump pressure to gravity feed.

[myates92]

The buffer tank is a really good idea, only problem is I don’t have much room to put one in reasonably. I think if I run some sort of pump (vacuum/ electric), I can run it through a adjustable regulator to get 0.5psi to the carb. Thank you for the math help, I was just going to fill the fuel bowls till the needle seats and pump air into the the inlet through a regulator till the needle unseats with a full bowl to get a ball park.

[myates92]

With dump bed shut.

[SibSerge]

if you attach it at the same level as you have your coil - in that corner next to the carbs it should still be ok as I can see

[myates92]

Yeah, that is a possibility too. Only thing is, I plan on running the exhaust pipes out that side and over the rear passenger tire. I’d hate for the tank to be that close to the exhaust.

[myates92]

But all things considered, you gotta do what works and what’s most simple to get the job done.

[SibSerge]

Originally Posted by myates92

Yeah, that is a possibility too. Only thing is, I plan on running the exhaust pipes out that side and over the rear passenger tire. I’d hate for the tank to be that close to the exhaust.

Ah ok.

[Mohawk]

Not sure about Kawasaki models but Honda VFR750 & a couple of 600 models had electric fuel pumps for their carbs. Check out their pumps.

[myates92]

@Mohawk, thanks! I'll look into that as well. Combing through some different forums, I've found that a lot of scooters use fuel pumps?? The things you learn when you do little projects like these haha.. Anyways, I may look into that too. Thank you all for the help, I have the fuel inlet on order that @ducatiman sent me. Once that gets in I'll button up the carbs and hang a can up to feed it for now, just to get it running. I'll keep the album updated from time to time.

[SibSerge]

Michael, what are you doing for cooling? I think stock system might not be sufficient in this case. If you upgrade the cooling I would suggest thermobob to be added. It does make the temperature of the liquid more even. I just did it in my ZZR - cannot be happier. Fast warm up and more even temp in cold weather

[myates92]

@SibSerge, I've somehow managed to retain the stock radiator and fan. And it's mounted in a somewhat relative location to stock. The previous owner of the bike had bypassed the temp sensor with a switch for some reason. Testing the harness, everything seemed to function normally. Fan came on when slight heat was applied to sensor. Upper radiator hoses and thermostat housing are stock location. Will have to modify a hose for the lower... As far as how it cools and efficiency, that's all going to fall in the "Teething Issues" boat, deal with it as it arises. But thanks for the info, I'll keep it in the notes.

[SibSerge]

Originally Posted by myates92

@SibSerge, I've somehow managed to retain the stock radiator and fan. And it's mounted in a somewhat relative location to stock. The previous owner of the bike had bypassed the temp sensor with a switch for some reason. Testing the harness, everything seemed to function normally. Fan came on when slight heat was applied to sensor. Upper radiator hoses and thermostat housing are stock location. Will have to modify a hose for the lower... As far as how it cools and efficiency, that's all going to fall in the "Teething Issues" boat, deal with it as it arises. But thanks for the info, I'll keep it in the notes.

Yeah keep an eye on the gauge. Your vehicle is slow by design and will not benefit from the high flow created by the movement. And I assume you will be using it for hauling stuff around. The stock fan might need to see some upgrade

[myates92]

Yeah it'll probably be a little on the slow side comparatively... from motor to mid shaft its 1:1, from mid shaft to transaxle it's 3.14:1, and the transaxle itself is like 6.5:1.. so it'll be geared to pull that's for sure.. at least however much the clutch will hold, I'm sure I'll find out soon enough haha.