Yamaha F200 R1 Engine Builders

S

sdwdhd1999

Member
I've got a engine sitting on a shelf and would like to know who still rebuilds these engines and has most of the available parts for them
20200407_045959.jpg
 
This may be a crazy question, but it doesn't make sense to me. Why does a pumper carb need an additional fuel pump?
 
MHSWildcat said:
Help me out here Mr. Carlson, apply a little 410 logic...
Click to expand...

Sorry, I just saw this post. Hopefully my reply doesn't get deleted.

I don't know about "410 logic," but the stock Tilly pump runs out at, or above, 7200 rpm, and can benefit from more head pressure at the pump inlet, thus the additional pump. Several factors figure into this: the length of the pulse tube, the length from the fuel tank to the carb, and more.
Keep in mind that many of the pumps that we use in karting are not meant to pull fuel from long distances, but rather to push fuel. We're asking a lot from them to pull fuel from lower to higher and across 3+ feet of distance. The extra pump simply helps out (especially on top end.) For some applications, it's overkill, sure, but I've never known an auxiliary fuel pump to hurt in our applications.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Ok, then I would believe, based on your reply that the remote fuel pump should be as close to the fuel tank as practical and push fuel to the carb.
Same as an intank fuel pump vs. one mounted on the motor plate. I asked for logic as in we constantly play with different fuel supply setups in
sprint cars, different volumes and pressures, supply line size depending on pushing or pulling, nozzles and by-pass. When we ran the fuel tank on
the back of the seat (not possible now) the pump on the carb was sufficient for the 820's and 101's of the day. It is hard to believe a 4-stroke can
run out of fuel just using the carb pump.
 
MHSWildcat said:
Ok, then I would believe, based on your reply that the remote fuel pump should be as close to the fuel tank as practical and push fuel to the carb.
Same as an intank fuel pump vs. one mounted on the motor plate. I asked for logic as in we constantly play with different fuel supply setups in
sprint cars, different volumes and pressures, supply line size depending on pushing or pulling, nozzles and by-pass. When we ran the fuel tank on
the back of the seat (not possible now) the pump on the carb was sufficient for the 820's and 101's of the day. It is hard to believe a 4-stroke can
run out of fuel just using the carb pump.
Click to expand...


Better yet would be a gravity fed carb. You can't put the aux. pump close to the tank, because it has to pulse off of the intake (or crankcase.) That pulse line needs to be kept as short as possible. I feel that's just part of the reason that the auxiliary pump is necessary at higher rpm.
The argument for increased head pressure still holds though, as increased supply to the stack pumps on the carb is as close as we can get to gravity feeding the carb (ie no good place to mount a fuel tank up high over the engine.)

On the sprint car, there are other factors (namely the return lines. We feed way more fuel toward the engine than it could ever digest. Higher volume to the pump (ie -12 or even -16 line before the pump, and -6 going to the engine.) Then we choke the fuel way down at the nozzle tip to create better atomization (either in the stacks (up-nozzle) or at the valve (down-nozzle.)) That increased pressure sprays a fine mist of fuel into the air-stream which aerates and mixes better, and combusts better when pressurized in the combustion chamber.
Then we could get into a whole long haired discussion on the bypass side with return pills, pop-off pressures, fuel curve, etc.

Whether it's a sprint car, or Briggs flathead with a Tilly, they want as much fuel as you can give them down low - up to peak torque, then the fuel curves needs to start breaking as rpm increases (less fuel on top end.)
 
Thanks Brian, Too bad you're so far away I would really like to debate some things with you. Fuel curves are the least of it. It's nice all the
builders are willing to share knowledge and much appreciated. Because we share a background (Karts and Sprint Cars) I bet the ideas could
get pretty lively and interesting!
 
I tend to be a bit wordy from time to time. :)

I still have the parts from an dry-sump open flathead that I played with back in the early '90s using a belt drive rear end cooler pump from a Nascar team and surplus nozzles from the sprint car.
Then there's the clear plastic sidecover for the flatty that we used to see what the oil was doing in the crankcase on different degree motor mounts on the dyno.
Lots of memories.
 
You must log in or register to reply here.
Back
Top