From MikesXS https://www.mikesxs.net/ultimate-flow-optimizer-ufo-mikuni-vm36-vm38.html
From the manufacturer https://thunderproducts.com/product/ufo-ultimate-flow-optimizer/ Thunder Products has a long history as a maker of addustable jetting, jetting while riding, and power valves, none of which I have tried.
Claims are:
"The UFO is a simple, trouble free, aerodynamic piece that fits VM Mikuni carburetors from 30 mm through 44 mm. The UFO makes a normal round slide carburetor out-perform the more expensive flat slide carburetor by eliminating turbulence and increasing air flow and velocity, creating a highly atomized fuel charge. Normal gains are 3/4 to 1 HP per 100 cc of engine displacement on 4 stroke engines and 1 1/2 to 2 HP per 100cc of engine displacement on 2 stroke engines. (Minimal rejetting and tuning are required).
Features:
More horsepower with less fuel
Broader power band
Explosive throttle response
Superior fuel atomization
Less sensitive to temperature, altitude and jetting changes
Cleaner emissions
Cooler running engine
Easier starting and warm-ups
Eliminates cold pipe syndrome
Works great with stock or modified engines
Hell Yeah!"
My experience:
For starters, it took me quite a while to get it jetted. Cutting jetting by half as suggested by the manufacturer is counterintuitive, after all, one would assume that faster flowing air would require bigger jets, not smaller, but the smaller jets work because the faster flowing air increases the ventura effect thereby increasing vacuum and pulling more fuel through the jets. Be prepared to spend a lot of time on jetting. I'm currently running a 120 main and can't remember which idle jet I finally ended up with.
I'm running a single 36mm Mikuni VM carburetor so I only needed one. Having to buy 2 would have broke the bank.
It really just modernizes the slide on the VM carb. I guess Mikuni never modernized the slide because they had already come out with better performing carbs.
Does it make more power? Before I answer that allow me to say, a lifetime of spending money on performance parts has taught me that nothing is as good as any manufacturer claims it to be. Pipes, cams, carbs, intakes, ignition systems... any high performance part you buy will not reproduce the kinds of results that can be made in a laboratory. Obviously I'm only relating seat of the pants experiences but there does seem to be a slight increase on the bottom end. As for top end and a broader power band I've no idea. I don't push my luck anymore.
Explosive throttle response? I'd say better, not explosive.
Superior fuel atomization? Who knows? One can only assume yes as I did note better throttle response.
Less sensitive to temperature, altitude and jetting changes? I donno, maybe, maybe not.
Cleaner emissions? Who knows?
Cooler running engine? I really can't say as I've only used it on cooler days.
Easier starting and warm-ups? Yes. My bike starts instantly even without using the enrichener/choke.
Eliminates cold pipe syndrome? That was never a problem for me.
Works great with stock or modified engines? My engine is stock.
Hell Yeah? That depends... are you expecting miracles? If yes then you will be disappointed.
Would I buy it again? If I were trying to make the most power possible I would buy it again as even 1 HP is sometimes enough to win the race.
That said, the snowmobilers seem to love it. https://www.google.com/search?q=ufo...BsAqSAQQxLjEwmAEAoAEByAEIwAEB&sclient=gws-wiz
From the manufacturer https://thunderproducts.com/product/ufo-ultimate-flow-optimizer/ Thunder Products has a long history as a maker of addustable jetting, jetting while riding, and power valves, none of which I have tried.
Claims are:
"The UFO is a simple, trouble free, aerodynamic piece that fits VM Mikuni carburetors from 30 mm through 44 mm. The UFO makes a normal round slide carburetor out-perform the more expensive flat slide carburetor by eliminating turbulence and increasing air flow and velocity, creating a highly atomized fuel charge. Normal gains are 3/4 to 1 HP per 100 cc of engine displacement on 4 stroke engines and 1 1/2 to 2 HP per 100cc of engine displacement on 2 stroke engines. (Minimal rejetting and tuning are required).
Features:
More horsepower with less fuel
Broader power band
Explosive throttle response
Superior fuel atomization
Less sensitive to temperature, altitude and jetting changes
Cleaner emissions
Cooler running engine
Easier starting and warm-ups
Eliminates cold pipe syndrome
Works great with stock or modified engines
Hell Yeah!"
My experience:
For starters, it took me quite a while to get it jetted. Cutting jetting by half as suggested by the manufacturer is counterintuitive, after all, one would assume that faster flowing air would require bigger jets, not smaller, but the smaller jets work because the faster flowing air increases the ventura effect thereby increasing vacuum and pulling more fuel through the jets. Be prepared to spend a lot of time on jetting. I'm currently running a 120 main and can't remember which idle jet I finally ended up with.
I'm running a single 36mm Mikuni VM carburetor so I only needed one. Having to buy 2 would have broke the bank.
It really just modernizes the slide on the VM carb. I guess Mikuni never modernized the slide because they had already come out with better performing carbs.
Does it make more power? Before I answer that allow me to say, a lifetime of spending money on performance parts has taught me that nothing is as good as any manufacturer claims it to be. Pipes, cams, carbs, intakes, ignition systems... any high performance part you buy will not reproduce the kinds of results that can be made in a laboratory. Obviously I'm only relating seat of the pants experiences but there does seem to be a slight increase on the bottom end. As for top end and a broader power band I've no idea. I don't push my luck anymore.
Explosive throttle response? I'd say better, not explosive.
Superior fuel atomization? Who knows? One can only assume yes as I did note better throttle response.
Less sensitive to temperature, altitude and jetting changes? I donno, maybe, maybe not.
Cleaner emissions? Who knows?
Cooler running engine? I really can't say as I've only used it on cooler days.
Easier starting and warm-ups? Yes. My bike starts instantly even without using the enrichener/choke.
Eliminates cold pipe syndrome? That was never a problem for me.
Works great with stock or modified engines? My engine is stock.
Hell Yeah? That depends... are you expecting miracles? If yes then you will be disappointed.
Would I buy it again? If I were trying to make the most power possible I would buy it again as even 1 HP is sometimes enough to win the race.
That said, the snowmobilers seem to love it. https://www.google.com/search?q=ufo...BsAqSAQQxLjEwmAEAoAEByAEIwAEB&sclient=gws-wiz
