Ever ridden a bike fitted with Smartcarb? I'm building a 2nd shifter kart & the company will be releasing specific variants for karts some time in late '22 to early '23. I'd like to read some firsthand reviews.

This guy seemed to be impressed:



If it performs as promised, my engine will burn cleaner/more efficiently, & there'll be no need to fool with jetting.

It would be interesting to see how it deals with the losses and other factors that make cylinders farther away from the carburetor get fuel-air mixes different than the ones closer.  It would probably be the end of the stop-start engine systems as well.

I know that intake manifold length is a tuning element, but is it heavily dependent on the type of carburetor used?

Can you expound on this?

It may well be a good carburetor but I don’t believe for a second it’ll be better than fuel injection.

Looks like a cool design and appears to be well made. It’s roughly the same price as a replacement Keihin carb so be worth considering if you have to replace a carb.

Carburetors are a precision complex device….that doesn’t really work that great. There is a reason most engines have moved to FI and aren’t coming back.

Smart carb is a brilliant piece of kit and I would prefer it to fuel injection.  My understanding is that they are really only applicable to 2 strokes though.  Something about the intake pressure waves in a 4 stroke engine causing the needle to wear rapidly.

Had one of a 250 2T enduro bike. Loved the performance and how the bike was always jetted damn near perfect. In my area it can easily be low 60’s in the morning then mid 80’s with humidity in the afternoon. The carb handled it well. It made the power more linear and my bike was less jerky while cruising on the road. It was also setup perfect from SmartCarb. Basically drop it in and ride. Ultimately I had to ditch it because the SC is larger than the factory Keihin and it was causing my intake boot to kink.

For a kart… you may like a perfectly jetted Keihin better. I’d imagine you aren’t lugging or cursing with a kart. More zero to WOT. Keihin should be stronger at WOT. I’d suggest a Keihin with a STIC metering block

If you really want a self adjusting carb on a kart then maybe consider a Lectron. Similar technology as a SC but it has a separate power jet circuit. This would allow you to tune you peak rpm conditions separately from low to mid rpm.

I like to think of a SC as better setup for enduro low rpm work and the Lectron better for MX/Drag

This company makes some.

https://thunderproducts.com/


Works pretty good on 2-stroke snogo s.

I put a lectron on my YZ250 and love it. My kid's, and wife's, machines can't accept one or I would get it for theirs. I did not have to do any tuning with the meter length or the power jet. I still like to pull my sparkplug after a ride and it's always that creamed coffee color, or the slightly gray rich.

I know how to tune a carb but damn sometimes it's a lot of effort tuning everyone's machine to be good for sand dune riding. If we only did trails I could accept how the carbs are set and get away with less tuning. Some trips I have to do all the main jets and needle clips on the kid's and wife's quads. I keep a log of the settings and weather conditions so I have an idea if just needle will get things done or if a different main jet is needed. I don't have enough elevation change to have to mess with pilots and most of the time I can get by with adjusting the air screw in the morning then move it back after it has warmed up in the day.

My biggest gripes with the Lectron is that the choke is on the wrong side of the bike and draining float bowl could have been made easier.

The smart carb fixes my gripes about Lectron but I don't want to spend another $700 to replace a carb that already does what it said it would which is auto compensate.

The smaller 2 stroke engines I have are the most noticeable when the jetting isn't on. The 90cc and 105cc often need some tinkering the first morning of a trip. The 400cc is harder to tell jetting could be better unless you set out with the intent tinker with jetting. The guys I know that have been able to put an auto compensating carb on a small cc bike have similar results as I do with my 250. My YZ250 is smooth with no bog from 60F to 105F and +/- 3000ft from my home base elevation.

I would say to have reasonable expectations of the carb. The auto compensating isn't guaranteed to keep your plug at optimal color. The auto compensating takes away the bog feeling that is what indicates you've got a traditional carb circuit to tune. If you're after peak perfect performance with nothing to adjust I don't see an auto compensating carb giving you that. With an auto compensating carb you'd still be making minor length variations or rod taper changes to chase perfection.