APT SmartCarb
- Thread starter gasgasman
- Start date
Jakobi
Super Moderator
I have lost track of APT. Didn't they change names? and then change back? I'm not sure. I just got my 38mm Billet back from a long hiatus and was considering contacting them to see if they'd be interested in bringing it up to latest spec and possibly giving it another burl to see how things have progressed.
I am currently having another crack at it after some time. its great while running but hard to start first thing and after a ride in the trailer. email sent to get their opinion.
check of the plug after day at the MX track shows rich so I will click left and see if that sorts it.
check of the plug after day at the MX track shows rich so I will click left and see if that sorts it.
Hey everyone. You can reach us for SmartCarb sales, service and parts at Technology Elevated.
816-255-2328
https://technologyelevatedco.com/ https://www.facebook.com/technologyelevated/
Corey
memphis2857
New member
My buddy has the exact same issue. He has to use starting fluid to get his bike to fire when it's cold
Sent from my iPhone using Tapatalk
its Summer in Tasmania and still have the trouble.
I had an early billet 36mm SmartCarb on my KTM 300XCW.
There were a few things early on to sort out (I expected that, being an early one)- bit once all done always started and ram great.
I sold the bike and sold th carb to a buddy with a 300. Worked great a long time, but began to have some issues like you describe.
My understanding a fix is avalaible (new check valves I think).
But I always had great service from Corey,,so giv him a chance to sort it.
Mark
There were a few things early on to sort out (I expected that, being an early one)- bit once all done always started and ram great.
I sold the bike and sold th carb to a buddy with a 300. Worked great a long time, but began to have some issues like you describe.
My understanding a fix is avalaible (new check valves I think).
But I always had great service from Corey,,so giv him a chance to sort it.
Mark
Installed my new 38mm cast last wknd. It's a bit early to give a full review as I've only had a couple short runs on it around the block. It does seem promising though, based on my initial tiny bit of playing around.
The first ride I fiddled with it enough to get the bike running and went for a quick spin, but it wasn't anywhere close to where it needs to be. No big deal as Corey recommends putting at least 4 hrs on it before fine tuning.
Today I played with it a bit more. It was a bit hard to start. It took about 6-7 kicks with the choke and it was only 2 celsius out. It seemed lean, so i richened it up about 7-8 clicks and that made a huge difference.
When I start it once warm, it fires about 1/2 way thru the first kick and settles into a nice idle, which is better than it's ever been. On the short ride I took, it pulled quite nice thru the gears.
Looking forward to spending lots of time on this bike this year and see what this carb can do.
There have been quite a few revisions made on these since they came out, especially the billet as well as 1 or 2 revisions with the cast versions, from what I understand. Mine is one of the later versions, as it was made last fall
I was quite impressed with the unit when I took it out of the box. Very clever design and incredible simplicity. There is really only a few moving parts and only 2 main adjustments. It appears once it's setup, the owner shouldn't need to mess with it anymore after that.
Love the fact that there aren't any hoses and other exterior junk.
The first ride I fiddled with it enough to get the bike running and went for a quick spin, but it wasn't anywhere close to where it needs to be. No big deal as Corey recommends putting at least 4 hrs on it before fine tuning.
Today I played with it a bit more. It was a bit hard to start. It took about 6-7 kicks with the choke and it was only 2 celsius out. It seemed lean, so i richened it up about 7-8 clicks and that made a huge difference.
When I start it once warm, it fires about 1/2 way thru the first kick and settles into a nice idle, which is better than it's ever been. On the short ride I took, it pulled quite nice thru the gears.
Looking forward to spending lots of time on this bike this year and see what this carb can do.
There have been quite a few revisions made on these since they came out, especially the billet as well as 1 or 2 revisions with the cast versions, from what I understand. Mine is one of the later versions, as it was made last fall
I was quite impressed with the unit when I took it out of the box. Very clever design and incredible simplicity. There is really only a few moving parts and only 2 main adjustments. It appears once it's setup, the owner shouldn't need to mess with it anymore after that.
Love the fact that there aren't any hoses and other exterior junk.
Have about 15 hrs on mine since it was installed. It should now be fully broken in. Have done a couple of small trailside adjustments since installing it & I think it's probably close, but still a bit on the rich side. I'm Ok with it being a bit rich, rather than a bit lean.
Once the bike is warmed up, there is very little smoke, although I still have a bit of spooge, but much less spooge than I used to get from the stock Keihin, which was admittedly running rich.
The bike generally starts in one kick when cold with the choke on, or if the starter is willing to work, it fires as soon as the button is pressed.
Here's a cool benefit. I did an organized ride yesterday. I used at least 2 or 3 fewer liters to ride to the lunch stop than I did on the same ride last year. Last year, I hit reserve at just over 80km(mix of roads and single track), with the lunch being at about 86km. This year, lunch was at the 80km mark and it took only about 6 liters to fill up. My bike has the 10.5 liter tank.
Weather conditions were similar to last year and trails were similar.
That is close to the mileage I used to get on my 250cc 4strokes.
Once the bike is warmed up, there is very little smoke, although I still have a bit of spooge, but much less spooge than I used to get from the stock Keihin, which was admittedly running rich.
The bike generally starts in one kick when cold with the choke on, or if the starter is willing to work, it fires as soon as the button is pressed.
Here's a cool benefit. I did an organized ride yesterday. I used at least 2 or 3 fewer liters to ride to the lunch stop than I did on the same ride last year. Last year, I hit reserve at just over 80km(mix of roads and single track), with the lunch being at about 86km. This year, lunch was at the 80km mark and it took only about 6 liters to fill up. My bike has the 10.5 liter tank.
Weather conditions were similar to last year and trails were similar.
That is close to the mileage I used to get on my 250cc 4strokes.
It should be written in the documents you got with the carb
RockefellerGG
New member
I have a 38mm Smart Carb. These were my factory settings:
Metering Rod: Q11
Factory Tuned Clicker Count: 63 Clicks
(Click count from full rich - Turn Right)
Slide Length 3.901
Idle Set-Screw Setting: .735"
Metering Rod: Q11
Factory Tuned Clicker Count: 63 Clicks
(Click count from full rich - Turn Right)
Slide Length 3.901
Idle Set-Screw Setting: .735"
I've only spent a bit of time fiddling with my SC, and it seems like it's somewhat close to where I want it. I spent some time last nite reading the tuning guide at the link gasgasman provided.
The more I learn about this carb, the more I come to think it is a pretty clever design. I've had to change my thinking about carburetors and how they work- at least this one anyways. Much of the process is initially counter-intuitive & you have to scrap the typical tuning process you'd use on other carbs.
At this point, I'm sold. Love the idea of set it and forget it. I'm going to do some final tuning this wknd.
The more I learn about this carb, the more I come to think it is a pretty clever design. I've had to change my thinking about carburetors and how they work- at least this one anyways. Much of the process is initially counter-intuitive & you have to scrap the typical tuning process you'd use on other carbs.
At this point, I'm sold. Love the idea of set it and forget it. I'm going to do some final tuning this wknd.
Unusual setting
Hello Guys,
I own a 2008 EC300, Stock Motor, Gnarly Pipe and FMF Turbinecore2. New Spark plug 1 size hotter BR7EG.
With the Smartcarb (38mm Billet) the idle is a problem.
With standard Setting(as delivered and documented in manual) Valve height2mm and needle+Slide/Rod length 99,1mm (3,901") I have a return from open Throttle with normal (desired) idle rpm, but after 1 or 2 secounds it drops and soon Motor stalls. I tried to lean the rod, but the high idle always sooner or later drops to stall.
I now had the following strategy: Make the Carb richer so rpm drops fast after open throttle and enhance idle (gap).
This leaves me at standard Slide/rod length 99,1mm but a stable return to idle. Only issue is, that idle gap is 3,7mm. Far away from the recommended 2mm(+-0,5mm).
Has anyone made similar experience?
By the way, my manual says the carb has a 35HiFlo Needle+seat. What does that mean?
Important for me is a very good consistent and predictable smooth power delivery from bottom, as I do X-Training with a lot slow tricky stuff. Ideally engine would behave like my 250TXT GasGAs trials bike.
In the EC300 my Keihin delivers here after endless mods(see below, except for stalling on steep descent).
Best regards,
Erhard
P.S.:
I am convinced i have no issues with air leaks, broken Membranes or such. The Motor runs good, switching back to Keihin PWK 38(slide9, N1EG clip2, Main 168, Idle 40, Idle screw 1,5T out, warmer spark Plug-important!). Only backdraw of Keihin is a delayed transition onto Pipe (Powervalve opening). In tricky Terrain it appears Keihin delivers softer Power(better than SC). Keihin tends to stall at steep descends.
I had endless tuning on the Keihin, starting with JD kit. Now I tried a #9Slide and feel to have the best combination now. #7 never was totally convincing. With N1ef/slide#7 it was always loading up in slow sections...endless as sayed. SC was better from out of the box, if only it idled...
Hello Guys,
I own a 2008 EC300, Stock Motor, Gnarly Pipe and FMF Turbinecore2. New Spark plug 1 size hotter BR7EG.
With the Smartcarb (38mm Billet) the idle is a problem.
With standard Setting(as delivered and documented in manual) Valve height2mm and needle+Slide/Rod length 99,1mm (3,901") I have a return from open Throttle with normal (desired) idle rpm, but after 1 or 2 secounds it drops and soon Motor stalls. I tried to lean the rod, but the high idle always sooner or later drops to stall.
I now had the following strategy: Make the Carb richer so rpm drops fast after open throttle and enhance idle (gap).
This leaves me at standard Slide/rod length 99,1mm but a stable return to idle. Only issue is, that idle gap is 3,7mm. Far away from the recommended 2mm(+-0,5mm).
Has anyone made similar experience?
By the way, my manual says the carb has a 35HiFlo Needle+seat. What does that mean?
Important for me is a very good consistent and predictable smooth power delivery from bottom, as I do X-Training with a lot slow tricky stuff. Ideally engine would behave like my 250TXT GasGAs trials bike.
In the EC300 my Keihin delivers here after endless mods(see below, except for stalling on steep descent).
Best regards,
Erhard
P.S.:
I am convinced i have no issues with air leaks, broken Membranes or such. The Motor runs good, switching back to Keihin PWK 38(slide9, N1EG clip2, Main 168, Idle 40, Idle screw 1,5T out, warmer spark Plug-important!). Only backdraw of Keihin is a delayed transition onto Pipe (Powervalve opening). In tricky Terrain it appears Keihin delivers softer Power(better than SC). Keihin tends to stall at steep descends.
I had endless tuning on the Keihin, starting with JD kit. Now I tried a #9Slide and feel to have the best combination now. #7 never was totally convincing. With N1ef/slide#7 it was always loading up in slow sections...endless as sayed. SC was better from out of the box, if only it idled...
Last edited:
siaknijustin
New member
If you're a member of the KTMtalk forum you might post the question over there. They have a sticky in the jetting section for setting up the SmartCarb that is fairly active and frequently updated. I couldn't ever get my SmartCarb to idle consistently but I can't rule out an air leak (maybe crank seals). I reinstalled the PWK but can't get a consistent idle with it either. If I ever get around to replacing the crank seals I'll try the SmartCarb again. Sorry, I'm not more help.
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