Have your balls dropped (smart carb)

[Patches88]

Slide

That picture is rounded so slide looks more open then it is.
It has a brand new motion pro throttle cable, bars move freely left/right and that slide doesn't move. Turned throttle out didn't help. Corey said not to touch the position after he upgraded it and that's what it looks like (bored choke circuit, hi flow floats, new metering rod).
Weird thing is Corey at APT says the CR500 needs the .076 but it won't even run with the throttle open to 1/8", engine dies, wet plug, Engine flames out when decelerating etc. Only the super lean .080 metering rod will come close to running at idle and it designed for the 300cc XC engines (will flame out after 2 secs idling).
Here it is at the MX track with the .080 metering rod, its running very crisp, too crisp to be a snowbike. It sounds "tinny" doesn't have that deep CR500 grunt.Engine dies on corners on this track with the .078 needle (tried between 40-120 turns out). It took 15 minutes to get the bike going for this video but it will start in 5 kicks only when hot.
https://www.youtube.com/watch?v=LyUQ_EvOZ8M
Here it is with the PJ carb & a worn out piston a few years back before it got the aluminum frame conversion, sounds a lot better and made more power because it was getting the fuel at the correct ratios. Same PC pipe and silencer in both videos, only difference is a new bottom & topend and Smartcarb at the MX track.
https://www.youtube.com/watch?v=I_zMy8FO9Ro
Which bike is making more power and running better? Its not rocket science to get a carb running on all circuits but their is something not right with the heavy breathing CR500 and the Smartcarb single circuit. Maybe the APT machine shop should have lapped in the slides like Mikuni and Keihin provide on theirs.

 

[mtn-doo]

Yikes.... ya, that was painful to watch. Don't be discouraged though. In those vid's, when you pull in the clutch for a corner the bike run's "nervous" and "zingy". That's a basic lean condition. That can be cured easily. Wheather it's a SC, PWK,TM,Lectron etc doesn't matter. When you did your carb swapping the PWK was tuned and dialed in. Yes, it will start and run excellent. When you swap to any other carb not specifically dialed in for that specific engine, it won't compare to the dialed in unit you just removed. I have had all those brands mentioned above that didn't start or idle in one application or another. The point I guess is that it's not the "object" making it start or run poorly, it's the correct set-up and tune. The CR and KX are both big 500CC single two strokes. Massive air pumps that move a lot of air. We have easy starting, smooth idling, aggressive accelerating CR's and KX's on Smart Carbs with the other added benefits. I wish you were a close neighbor, we would have you tuned spot on quickly.

Here are three examples. Lots of fuel for these big 500's equals smooth steady idle without that nervous behavior. Zero pipe buzz or vibration and if you listen closely, you can hear the piston rattling with each stroke. They idle freaky smooth like a sewing machine when tuned correctly.

https://www.youtube.com/watch?v=8aq1Hjf3JD8

https://www.youtube.com/watch?v=4e55g6Y4ppQ

https://www.youtube.com/watch?v=qijiGuEmOok

 

[wwillf01]

That picture is rounded so slide looks more open then it is.
It has a brand new motion pro throttle cable, bars move freely left/right and that slide doesn't move. Turned throttle out didn't help. Corey said not to touch the position after he upgraded it and that's what it looks like (bored choke circuit, hi flow floats, new metering rod).
Weird thing is Corey at APT says the CR500 needs the .076 but it won't even run with the throttle open to 1/8", engine dies, wet plug, Engine flames out when decelerating etc. Only the super lean .080 metering rod will come close to running at idle and it designed for the 300cc XC engines (will flame out after 2 secs idling).
Here it is at the MX track with the .080 metering rod, its running very crisp, too crisp to be a snowbike. It sounds "tinny" doesn't have that deep CR500 grunt.Engine dies on corners on this track with the .078 needle (tried between 40-120 turns out). It took 15 minutes to get the bike going for this video but it will start in 5 kicks only when hot.
https://www.youtube.com/watch?v=LyUQ_EvOZ8M
Here it is with the PJ carb & a worn out piston a few years back before it got the aluminum frame conversion, sounds a lot better and made more power because it was getting the fuel at the correct ratios. Same PC pipe and silencer in both videos, only difference is a new bottom & topend and Smartcarb at the MX track.
https://www.youtube.com/watch?v=I_zMy8FO9Ro
Which bike is making more power and running better? Its not rocket science to get a carb running on all circuits but their is something not right with the heavy breathing CR500 and the Smartcarb single circuit. Maybe the APT machine shop should have lapped in the slides like Mikuni and Keihin provide on theirs.

It really seems like all these engines are severely different even from the same models.. my cr runs great on a 38mm q5 from 5000 to 10000 spot on using 110... after running these on a 300 (q11 was the one that worked even with the porting on this one) and 500 along with a lectron I am sold on both companies.... I did like the Lectron ability to richen the top end with the power jet... I wish the smart carb would add something like this.. still tuning was required... bit once they were set up I rarely had to touch anything more than the idle...

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[summitboy]

Im kinda with you on this. Some of the noticeable differences are engine state of tune. Some are stock, some light ported, some heavy ported, some TWIRP ported etc. The Smarty just doesnt cover it all with the rods available. There seems to be a lot of inconsistency on all the bike brands Hondas, KTMs etc.

The Smarty is supposed to be super easy and tuning free which it hardly is. Tuning the carb is supposed to be as simple as turning the adjuster. I personally tried the 76-80 needles and believe me i tried every click to make it work for me. Corey himself spent hours on the phone with me trying to get it running right. We started on the 76 and he led me down the path to going back to the ultra lean 80. Its the only needle that would start and idle poorly. WOT wasnt bad but not great. I gave up after a whole season of testing and tuning. I switched and thankfully have a great solution with the Pulse. Had it tuned in one ride.

I have talked to many many guys with the Smarty over email and text and the very few that are so called tuned have a different engine configuration or different brand bike altogether. I have been keeping stats and there is no consistency period. I find it funny thats some believe it can fit and work on all bikes. Ask the KTM 380 crowd about it.

 

[wwillf01]

Im kinda with you on this. Some of the noticeable differences are engine state of tune. Some are stock, some light ported, some heavy ported, some TWIRP ported etc. The Smarty just doesnt cover it all with the rods available. There seems to be a lot of inconsistency on all the bike brands Hondas, KTMs etc.

The Smarty is supposed to be super easy and tuning free which it hardly is. Tuning the carb is supposed to be as simple as turning the adjuster. I personally tried the 76-80 needles and believe me i tried every click to make it work for me. Corey himself spent hours on the phone with me trying to get it running right. We started on the 76 and he led me down the path to going back to the ultra lean 80. Its the only needle that would start and idle poorly. WOT wasnt bad but not great. I gave up after a whole season of testing and tuning. I switched and thankfully have a great solution with the Pulse. Had it tuned in one ride.

I have talked to many many guys with the Smarty over email and text and the very few that are so called tuned have a different engine configuration or different brand bike altogether. I have been keeping stats and there is no consistency period. I find it funny thats some believe it can fit and work on all bikes. Ask the KTM 380 crowd about it.

I can tell you this the Lectron came for my Ktm and was a few rod turns from tuned... it was a much easier set up.... I think the difference is he dyno each bike and sends the carb pretuned on the rich side... at least that was my experience... I am going to be trying one on the kids kx65.... so we will see because it is a picky little bike

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[Dogmeat]

For those of you guys who put this carb on a 2012+ KTM 300 XC or XC-W, what did you do to 'trim your airbox'? Reason I ask is I just put the carb on my bike today and had a good day with it, getting it dailed in, but my air box to the carb throat is pinched pretty good. I didn't notice that the bike appeared to be down majorly on power, but I can't seem to find a good way to make it fit ....

I freaking LOVE the ease of tuning on this thing. I was literally trying to load my bike up atlow RPMS and it never flooed once, just ran great

 

[mtn-doo]

Remove your boot and use the bending reducing coupling from silicone intakes. 2.5 to 3 and 45 degrees.

 

[wwillf01]

For those of you guys who put this carb on a 2012+ KTM 300 XC or XC-W, what did you do to 'trim your airbox'? Reason I ask is I just put the carb on my bike today and had a good day with it, getting it dailed in, but my air box to the carb throat is pinched pretty good. I didn't notice that the bike appeared to be down majorly on power, but I can't seem to find a good way to make it fit ....

I freaking LOVE the ease of tuning on this thing. I was literally trying to load my bike up atlow RPMS and it never flooed once, just ran great

Or order a modified airboot from cycle playground for summer. .. it will eventually start stress cracking. .. I have gone through 2 of them... one year with a Lectron and 1 year with the smartcarb ...

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[Dogmeat]

Remove your boot and use the bending reducing coupling from silicone intakes. 2.5 to 3 and 45 degrees.

Would you happen to have a picture of that setup installed on the bike by chance?

 

[summitboy]

Has anyone tried a stiffer spring on the slide by chance on the Smartcarb ? Ive heard some say it may not be strong enough for a super strong signal 500. Any testing ?

 

[mtn-doo]

Would you happen to have a picture of that setup installed on the bike by chance?

Yes, it's under the Ultimate 300 build thread. If needed, I will post more pic's.

 

[Patches88]

Weak Spring?

So I installed a brand new 1994 Honda OEM Ignition including flywheel to match year of engine. With the 38mm PWK air striker it fires right up and idles perfectly.
This video is with the 38mm Billet, it fires but will not stay running with the 38mm Billet set where APT set it after the upgrades.
It seems to act like the weak spring throttle valve is opening under the high vacuum from the 500 engine.
I sent this to Corey and will see what he says although I've been f**king with this since last August this was my last attempt and its going back to APT and the PWK is staying on.
https://www.youtube.com/watch?v=H9d7U1acTzk

 

[Patches88]

PWK back on

So I installed a brand new 1994 Honda OEM Ignition including flywheel to match year of engine. With the 38mm PWK air striker it fires right up and idles perfectly.
This video is with the 38mm Billet, it fires but will not stay running with the 38mm Billet set where APT set it after the upgrades.
It seems to act like the weak spring throttle valve is opening under the high vacuum from the 500 engine.
I sent this to Corey and will see what he says although I've been f**king with this since last August this was my last attempt and its going back to APT and the PWK is staying on.
https://www.youtube.com/watch?v=H9d7U1acTzk

and here this morning I re-installed the Keihin PWK airstriker and it started first kick. Nothing else changed.https://www.youtube.com/watch?v=C_cAjkaE_YA
I hope this helps you guys save a few bucks.
Patch
A little run up the street with the engine still cold.
https://www.youtube.com/watch?v=jrNeyvmkcOQ

 

[the gman]

Patches that sucks. I tried three different smarties and the last one I got, a 38, ran good but still over temped wide open, but would also flood out on any down hill decent. I tried different float heights to cure, didn't help, there are two orings around the noozle that may have caused my flooding on the last carb, but I got frustrated being told I was the only one having issues and moved on. i have installed a primer on both my bikes, kx500 and ktm 300 and that is the best thing anyone can do,hands down.

 

[summitboy]

Patches wait until your try a pulsed PWK ! Cant wait to see your thoughts on that setup. I so feel your Smarty pain ! So frustrating ! Kinda interesting how all the Smarty problems i have talked to guys about instantly go away with a PWK carb. Smarty will end up being like the Edelbrock metering carb that lasted for a couple of years.

 

[Patches88]

The Pulse

I like the idea of the Pulse Injector especially since its more flexible with elevation change that a stock Keihin. Just not sure it will fit in my CR125 frame with the 500 stuffed inside, but I'll find out, more money can cure anything lol.

 

[Patches88]

Float Balls Stuck

OK since the SC is sitting on the bench not being used I decided to pull these brass valve cages.

So one of the green balls was stuck in the top of the valve cage. This means atmospheric air could not get past the ball into the float bowl. The other ball was OK. This may explain why it would only run with a 0.080 MR? Wasn't getting enough air so it accordingly reduced the fuel maybe?

So how do I remove this sleeve in the cage?

These valve cages should be threaded, they are just a friction fit.
What should I seal the friction fit with after removing the green balls lol?

Oh and the choke thread sealant APT uses is powdery crap that may cause a bypass in the choke circuit. How would you ever know unless you pull the choke from brand new and use a thread sealant that won't deteriorate into a sticky powder. Corey says to clean it out with air and reseal it with some light blue thread locker.

 

[the gman]

To get the sleeve apart you have to run a sheet metal screw into one side, and hold the other with out distorting it so it will go back in. I will bet your sealing surface is tapered and Corey will send you non tapered ones for 10 bucks a piece, to correct them. Do yourself a favor, remove all balls, vent the bowl to your air box, install a q5 needle set to idle good, not pig rich, plug air scoop with plugs, install a thunder product power jet for wide open and a primer for starting and your set. That's what I did and mine is altitude compensating as it ever was.

Ps. Or you could save yourself a lot of headache and just go lectron, and some cash...

 

[wwillf01]

To get the sleeve apart you have to run a sheet metal screw into one side, and hold the other with out distorting it so it will go back in. I will bet your sealing surface is tapered and Corey will send you non tapered ones for 10 bucks a piece, to correct them. Do yourself a favor, remove all balls, vent the bowl to your air box, install a q5 needle set to idle good, not pig rich, plug air scoop with plugs, install a thunder product power jet for wide open and a primer for starting and your set. That's what I did and mine is altitude compensating as it ever was.

Ps. Or you could save yourself a lot of headache and just go lectron, and some cash...

Having both I think there is just too much going on in the smart carb that can malfunction while the Lectron works almost as good just more of a pain to adjust the lowend... but at the end of the day I like it better for durability and the ability to adjust for more fuel at the higher RPMS externally through the power jet.

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[the gman]

Patches I was told to use red loctite when reinstalling the brass cages into the carb. I have left the steel balls in but the green float balls should never been installed.