Running dual 44s on single pulse cases

[yamanube]

Had a buddy bring his ski over for some help tuning and somebody had installed a pair of OEM 44s in place of the 38s. They retained the fuel selector and split the inbound fuel line after the fuel filter and split the pulse line to both pumps.
This seems like a poor way to do things in my opinion but can it be made to run like this or do we need to install a second pulse and plumb it with dual fuel lines?

 

[Big Kahuna]

On Pulse, Yes, add a 2nd fitting. On Fuel, you will be fine with it split.

 

[Vumad]

I used a 8" extension and a ryobi speed bit to add a second pulse line to my case while the engine was assembled. The extension with the speed bit can wobble so you need to be careful. I drilled a pilot hole first and then the actual size which controlled the wobble. I put the pulse fitting in with a little JB weld. I don't use that motor a lot but it hasn't given me any issues.

 

[SELF27]

I bought a r&d angled reed spacer which had the second pulse line built in. If I didn’t buy the spacer I would have drilled. Maybe you can find r&d reed spacer so you don’t have to drill?



In pic it was just looped to keep debris out of motor.

 

[fastgtfairlane]

ive run dual sbn 38s on a kawi engine with a t to a single pulse but had dual feeds. ran great no issues. i dont see why you couldnt do the same on a yamaha engine. dual pulse and single feed doesnt make any sense to me. id much rather have dual feed personally although i know most factory setups are single pulse single inlet so basically the front carb is the "slave" carb

 

[Freakrider]

Pretty sure Yamaha runs a single fuel feed on triples.

 

[Vumad]

ive run dual sbn 38s on a kawi engine with a t to a single pulse but had dual feeds. ran great no issues. i dont see why you couldnt do the same on a yamaha engine. dual pulse and single feed doesnt make any sense to me. id much rather have dual feed personally although i know most factory setups are single pulse single inlet so basically the front carb is the "slave" carb

Did the dual 38s have 2 fuel pumps? OEM 38s has a single fuel pump on a master with a slave carb that has one less plate. OEM 44s have fuel pumps on both carbs. Many people modify their primary pickup to the same length as their reserve and run each carb to it's own pickup on the tank.

I had to drill my case and put the pulse in because it's and X2. Couldn't give up the space in the hull.

Edit: Not to say this doesn't mean that a person can't tee a pulse. Only just clarifying the routing differences in OEM 38s vs 44s.

 

[Vumad]

Pretty sure Yamaha runs a single fuel feed on triples.

My GP1200 had a single fuel tank pickup with 3 fuel pumps each with their own pulse line.

 

[fastgtfairlane]

Did the dual 38s have 2 fuel pumps?

yes the sbn 38s i used were not oem carbs. they each had their own fuel pump. in the tank i lengthened one pickup to make them both equal length then ran one to each carb. i teed the returns. i found a really good deal on ebay for the carbs. they were 75 bucks each. both carbs were the same. no choke, had primer fittings, cut down one of the throttle shafts and got a linkage kit to make it work.