Cast Smart Carb has arrived!

[rablack21]

I only got a sec to open this thread with, but there will be much more info to come soon! For now, here are some pics of it installed on my R. By the way, Here is the specs of the quad that the smart carb went on:
ESR 310cc power valve
Vforce 3 with new reeds
B8es plug
CR250 ignition
14:1 CR, 110 race fuel
Sparks MX exhaust

[rablack21]

There are also some pics thrown in there of my Keihin 38mm A/S that I replaced.

[ytman]

You must be stoked. I hope it's everything you expect.

[hickwheeler]

will be watching to see how this goes for you. The smart carb interests me. what are you going to do with the a pwk as

[rsss396]

Nice!

[Fire1]

Can't wait to here some results

[rk88r]

[rablack21]

Alright folks, I have much to reports. So I will try to include as much info as possible, but this will take several posts. I know alot of you have been watching with anticipation. I will start with Installation:

1. Installation:
Installation was very easy with just a couple minor issues. The carb inlet-outlet length was exactly the same as my Keihin 38mm A/S so the fitment was just the same. It fit very well in the reed cage and air filter boots. The issue I ran into was that my throttle cable was not long enough. I got this cable about 10 years ago and for some reason it didn't have enough adjustment to let the slide drop all the way down in the carb. But I had bought a new replacement cable to keep on hand, so I tried it on the carb and it worked just. If you look in my posted pics, take notice of the cable that has the extra cable adjustments right there about 10 inches away from the thumb throttle. This was the new replacement cable that I had on hand. This is the one that everyone recommends to buy when you need a new cable. I don't know why my old cable didn't work other than maybe it was made specifically for my Keihin carb. Anyway, with the new cable mounted, the carb slide was good to go.

*Point of note about fitment and adjustment.
The adjuster screw for cable length that screws to the top of the carb and has a jam nut that is recessed in the carb body. See pics. The directions say to tighten this jam nut using snap ring pliers. This method does not work very well, and I found this nut very difficult to get tight enough to keep it from vibrating loose. I think that a full size nut needs to be used in place of the jam nut, so the depth of the nut will sit high enough out of the carb recess to get a hold of it with a wrench. For the time being, I tighten mine by tapping the nut with a chisel on the corner of the nut and using a tad bit of loctite.

With that said, this completes all the issues/inconviences that I ran into with this carb. The cable thing may just be a fluke or have nothing to do with APT at all. The jam nut adjustment issue, I feel could have been done a better way. But, at least it is a minor issue.

[rsss396]

I agree that you should just put a taller nut on it or even make one if needed since you do not need to make a adjustment there, but then you could just red locktite it, that way it does not need to mechanically tight but yet the nut will not move.

[rablack21]

I agree that you should just put a taller nut on it or even make one if needed since you do not need to make a adjustment there, but then you could just red locktite it, that way it does not need to mechanically tight but yet the nut will not move.

You do actually need to make an initial adjustment there, but once it is made, then, yes, it could be loctited down, which is what I did. It did take some adjusting to get the thumb throttle to open the whole throat of the carb. I am running a 400 ex thumb throttle and it just barely has enough travel. And yes, the cavity of the thumb throttle has been ground down as much as possible. I may switch to another thumb throttle I have liked mine for a while.

I will update with some more initial observations very soon. Gotta find time and still get some work done! lol. Bare with me. I know you all want to know how it runs, and I will fill you in very soon. I will say, there is much to be excited about!

[brewer_brewer]

Whoops didnt aee that you ground it down already

[havinnoj]

Very cool.  Looking forward to reading how the setup and tuning goes.

[rablack21]

First Start/Ride:

A couple kicks and it fired up.

Observations:
1. It smoked a little but not very much. Much less than before
2. throttle is super crisp, revs very freely
3. Throttle return spring is very light, lighter than my keihin with some coils cut off
4. Isn't not idling well, sometimes dies. According to instructions, this is normal/expected.

I finish waiting for it to warm up and take it down the road. I haven't touched the mixture knob yet at this point.

Observations:
1. throttle response is very crisp
2. Powerband is smoother than before, the initial hit is a little softer more relaxed
3. Engine carries itself well even at low rpms.
4. Over rev is more noticeable. Previously, my other carb would fall on it's face and sound almost like a miss with I would over rev it. Now the engine still pulls in over rev, not a great deal, but       noticeable. And the engine still sounds like it is handling the fuel better.

At this point, some questions you may ask:
Does it have more power than before? Uncertain yet, but I would definitely say it has more usable power
Does it get better fuel mileage like claimed? Don't know, only have ridden it in a small area of woods by my subdivision. Haven't been out to the track yet.

Next I will post up my experience with playing with the mixture clicker. Guys, feel free to ask me any questions you like if I forget something. I don't have a video yet. I will have a race video to post after this weekend.

[rsss396]

In my experiences, slightly more fuel on the bottom end makes good torque and slightly less fuel on the topend makes best power.

Maybe Mr Hall can share his tuning experiences

[rablack21]

First Impressions/Experiences getting to know the Smart Carb:

Ok. So here's my experience thus far after playing with the mixture screw a bit and running it some. Again, bear in mind, all I can tell you is how it "felt" to me. This is my feedback.

I richened the screw 5 clicks and then rode it. The bottom end "hit" came on a little stronger but seemed like at a slightly later rpm. The top end also seemed to be a little stronger.
I richened 5 more clicks and repeated. Again, the bottom end "hit" was just a tad stronger, but about the same rpm as before. But it seemed noticeable that the top end was again pull harder.

I then put it back in the factory set position, and then went 5 clicks to the lean side. The bottom end was very responsive! I would say "violent" but more instant. The "luggability" increased quite a bit. The power band "hit" has been reduced, not quite as strong/pronounced. The top end was also smooth to the point of feeling like it pulled less hard. The engine has also gone to a more solid monotone sound through out the rpm range.

The changes I notice are more pronounced on the idle-midrange than the midrange-WOT, even though it feels like there is a little bleed over.

It's almost like you are tuning the powerband instead of the carb. It really feels interesting how the power changes as you richen/lean the mixture screw. No, I haven't used it enough yet to find the "sweet spot" or my preference, for that matter.

Again, please keep in mind, I have had limited time riding this, so these are my first impressions from experiments.