2stroke carb on 4stroke

[DP138]

I was at branson MX yesterday and i saw a YZ250F with a 2stroke carburetor on it. im positive it was a 2 stroke carburetor and i was wandering why they would have it on there. if it would improve power, ease starting, or anything. does any one know?

[mx221]

i dont think that would work. even if it did, i dont think there would be any power advantage at all without the accelator pump. i think you saw wrong

[DP138]

im positive it was a 2stroke carburetor, but i never saw the bike on the track. it was just sitting there lookin all pretty

[titoheadfaceman]

maybe it was an aftermarket carb. Just as mx221 said, without the accel pump it would be no could. It would just cough and stall when the throttle is ripped open. If it was a 2 stroke carb, then that is why it wasn't on the track, because it would barely work.

[sidekick]

You can run a 2 stroke carb on a 4 stroke. Jetting changes have to be made. 2 strokes have a different type of needle jet. Altough there were some 2 strokes that used a 4 stroke needle jet, Yamaha's RD350 and RD250 did. You would not be able to "snap" the throttle open, you would have to roll the throttle on. This is why there is a accelerator pump on modern 4 strokes.

Not sure why anyone would want to do a swap on a new 4 stroke though.

[RMXC51]

Yeah, seems pretty stupid when the stock Keihin works so well.

[DP138]

the bike was under a pretty big tent by a huge rig and you could tell the bike had tons of money into it. so im sure they knew what they were doing. i just dont know what

[ttr125lerider]

not sure about mx bikes.. but people with ttrs do it all the time with yz80/85 carbs. supposively gives much more top end.. jetting is a bi#$% though