APT Smart Carb

[Lotus54]

I blew way too much on a fancy new carb. APT Smartcarb. No jets, single circuit. Adjustable with no tools in seconds. Claimed much better atomization, better power, furl mileage, altitude and temp compensation.
Here is a review of the first ride;


Finally had a chance to get my 2009 300 with a 36mm SmartCarb on it out in the woods.

Starting, had to use the choke when cold (39f, 300ft elevation, probably 99% humidity)
Ran crappy when cold (no news there, it always does) but seemed to warm up quicker.

Ran perfectly on the road up to the riding area (my 300 is plated).
The start in the dirt is a very steep, rutted, very slick hill with turns and rocks/roots/limbs in the rut. Lots of fresh big leaf maple leaves and it was raining by now.
I adjusted the mixture a cople of times, seeing what difference it made.
I like the way it runs for that sort of thing just a bit on the rich side. Not as 'zingy' with better torque and much better traction (well, that's what it seems to me anyway).
The slightly leaner setting had quicker throttle response, but for this sort of thing I don't like that- I run trials tyres and they have fantastic traction, but work a lot better if you don't spin them up too much.
So, I could quickly adjust it for optimal response.
I did find it a little difficult to tell when I had it 'in the slot' and found getting off the bike and removing gloves was better. Someone else (or me with more practice) may not have this issue.
Well...if yo can call complaining that I have to actually get off the bike and take a glove off an issue!
It is so much easier and faster to change how it runs it is no comparison.

So with the potential goofs on if I had the slot engaged, I sort of lost track of where I was from factory setting. I guess no big deal as long as it runs right.

Anyway, a combination of adjusting the needle and switching the ignition 'full power and low power' was excellent and could complete change the character of the bike!
For the slick, slimy, technical hills and tight stuff I like a 'calmer' throttle and lower power.
For more open places that I am going faster, I like full power to loft the front end easier (generally only a few inches) even when in a gear or two high.

I think the carb has better response, better over rev much, much easier adjusting and also worked quite well for the few thousand feet elevaton change I made (probably wouldn't have made that much difference on a stock carb, but perhaps more even throughout)

I haven measured fuel used, but looking at the tank I think it was about a gallon for 40 miles, some 10 miles of road the rest single and two track- not maybe 25mph speed.
I'll try and get a measurement of fuel used.
I never really paid all that much attention to the amount of fuel used before, so can't help out on that too much- wish I could.

I'm not sure it smoked any less, perhaps.
BUT since I tend to run very low RPM and a bit rich settings, I've had many, many hours of sponge in the exhaust. So I'd really need to clean it out to tell. I'm sure there is a lot from before still inthe system.

All that said, I'm quite impressed with the carb. I had the settings very good before, but it runs better everywhere and much much easier to fine tune. I'm hoping less adjustments will need to be made for elevation and temperature, but only time will tell on that.

High recommended!

(Thinking of a pair for my Aprilia RS250 roadracer- but it would have to be cast)


Mark

[John H]

Sounds like a real high end candy item. I'm just thinking, how would it correct the air/fuel ratio or altitude density? One of the big headaches at Bonneville is the fast changing weather which affects jetting. The Smart carb sounds great for this application.
As for price, I might have to pawn one of my bikes to get a couple of them.

[DougErickson]

These really have me intrigued for the mighty 2000 380EXC. 380s are known for jetting challenges and it is true! I have mine as good as anybody ever has mostly by running a Honda CCL needle but it is not perfect. I did the JD Jetting thing but found it inferior. I have a near mint Lectron from back in the day but have never mounted it on a bike. If the APT were half the cost I would do it in a heartbeat but at $500 I want hear some testimony from 380 owners first. Its great to hear your having good luck Mark, keep us posted. Doug

[Lotus54]

Cast ones are $375.
These are supposed to be much better that the Lectron, but of course a further development of it.

I have seen anyone mention using it on a 380 yet, but you could keep an eye out on KTMTalk thread.

I believe they say due to the float pressurization method is how it altitude compensates.
Of course all carbs work by pressurizing the float chamber (with atmospheric pressure) but with no external vents and the much improved 'signal' at the Venturi, it compensates. (Well, more or less)

Compared to the price of other carbs the cast ne isn't bad at all. Especially since you don't have to buy a bunch of jets.
Try are working to get the price of the needle down (currently $19) which adjusts from abut half to full throttle.

[GUZZME]

Thanks for the post Mark. Don and i were looking at them online just days before you got yours. We both figured you would be the 1st guy in town to get one anyway! Iam glad to hear its working out for you. We were thinking of getting a dealer agreement with them,I think we're goin to now. Braaaap!!