APT Smart Carb: History, Design, and Tuning Tips

[SmartCarb]

Where are you obtaining your O2 samples in the bike in the video? Are you collecting your sample after it discharges from the muffler, using a sniffer tube inserted through the muffler or through a hole drilled somewhere in the expansion chamber or do you have the O2 sensor sampling directly from a welded in bung somewhere in the expansion chamber?

Samping directly from a welded bung about 10" from the piston.

We use different size needle/seats for gravity fed or pumps. Typically 3.5 for gravity and 1.5 for pumps.

[SmartCarb]

Thanks tony, no offence to anyone but it makes me think of Cannondale and the fact that they could have been successful with one more year of testing before releasing to the public. I bought a Cannondale but I don't think I will own one of these.

I'm not sure your measure of success. Less than 5% of a little over 1000 units (billets and cast combined) have or are having any issues. Some have been in the field for over 5 years and those report they just keep getting better. Forums were made for discussing issues, but if you were to look at the really large forum threads, like KTMTalk and GasGas you'll easily find more positive reports than negative, and most of those problems were related to issues with the bike or improper tuning. No were not perfect,  but as more and more product gets out there and bikes start showing up from the factory with an SC folks will get a better idea of what this is really all about.

[SmartCarb]

I got to ask are there any gains in horsepower or torque to be had with this carb,or is it the ease of tuning it that attract people to buying it.Maybe I'm just to old ,but I don't get it

Jetless,  two external adjustments.
Superior atomization.
Automatic altitude compensating.
Typical 10%+gains in HP-8%+ gains in torque.
Typical 30%+ gains in fuel economy. (2ts)
50% reduction in HC and particulate emissions. (2ts)
Linear throttling with no circuit overlap.
Multi fuel capability- pump fuel, racing gasoline, alcohol, Nitro, #2 diesel, Jet-A, and military spec JP-5 and JP-8.

[Pumashine]

Tony, I didn't see anything specific to a mod on this build sheet, is why I ask, and likely a Q-11 MR would not be correct.

Great to talk to you Corey, I guess Tom did not write down it was going on the 431 puma and the new one on a 486 baby saber. I am switching to FMR's that are 2 steps richer for the bigger displacement. The guy answering the phone just wrote down 250r based motor. He did not specify it was going to be used on a 431/486 which is considered a MOD engine. The old 40mm SC needle/seat was damaged by the vibration from the carb rubbing the intake on the motor. I'm sending it back for repair and to get the richer 076 FMR put in. APT is great to work with. You can call them for any questions you have after reading what Ryan has been recording in this thread. Thanks to Ryan for taking the time to get this new info out to us guys so we can move our dinosaur's into the 20th century

[fearlessfred]

Jetless,  two external adjustments.
Superior atomization.
Automatic altitude compensating.
Typical 10%+gains in HP-8%+ gains in torque.
Typical 30%+ gains in fuel economy. (2ts)
50% reduction in HC and particulate emissions. (2ts)
Linear throttling with no circuit overlap.
Multi fuel capability- pump fuel, racing gasoline, alcohol, Nitro, #2 diesel, Jet-A, and military spec JP-5 and JP-8.

thanks for the answers and the respectful way you answered.