The Honda Owners Club

Hi all, Im just wondering what the fuel pressure entering the carbs should be. Ive got a set that Im putting on a car engine but I dont know what fuel pressure they need.

Many Thanks
Ryan.

I guess you're not a bike rider then?
Carbs don't need 'pressure' as you put it. Most bikes simply have the fuel gravity-fed from the fuel tank to the carbs below it. Even the more complex bikes which do have a fuel pump (I'm not sure, but the '90 CBR600 might have one) can still work without the pump (as it has been done when the pump fails........), so it is not an absolutely essential item (unless of course, the tank is under the seat). I don't think you will find the information you want in a manual either.......
Someone who has fitted bike carbs in a car may come along with the answer.

Typically 4-5 PSI is what's required. Any more and the carbs will flood. Most low pressure electric fuel pumps will be of this order and would be suitable. Don't use a roller cell fuel injection pump.

Regards

Chimpy

Red V Four wrote:I guess you're not a bike rider then?
Carbs don't need 'pressure' as you put it. Most bikes simply have the fuel gravity-fed from the fuel tank to the carbs below it. Even the more complex bikes which do have a fuel pump (I'm not sure, but the '90 CBR600 might have one) can still work without the pump (as it has been done when the pump fails........), so it is not an absolutely essential item (unless of course, the tank is under the seat). I don't think you will find the information you want in a manual either.......
Someone who has fitted bike carbs in a car may come along with the answer.

I am, Ive got a yamaha xt660x And I know most carb'd bike are gravity fed since the tank is only 4-5inches above the carbs. But with it being a 600cc and having 4 of the things I though they might need a pump on the bike.

Chimp Boy wrote:Typically 4-5 PSI is what's required. Any more and the carbs will flood. Most low pressure electric fuel pumps will be of this order and would be suitable. Don't use a roller cell fuel injection pump.

Regards

Chimpy

Thanks for the information mate, looks like Ill have to buy a FPR.

Ryan.

rtlkyuubi wrote:

Red V Four wrote:I guess you're not a bike rider then?

I am, Ive got a yamaha xt660x And I know most carb'd bike are gravity fed since the tank is only 4-5inches above the carbs. But with it being a 600cc and having 4 of the things I though they might need a pump on the bike.

Apologies, but we've had some Honda car-owners on here before (not realising this was a Honda motorcycle site!), asking some strange questions!
A huge number of 600cc-plus bikes in the past have not had fuel pumps, many of them with four carbs and cylinders, but a lot of the much more modern later carbed bikes did.