APT SmartCarb

Corey said:
Phil, its all about the signal to the metering rod: The thing to remember is a caburetor is a passive device and can only respond as well as the engine it?s attached to; in terms of airflow and overall efficiencies. The shape of theSmatCarb?s venturi does an outstanding job of communicating mass airflow to the metering rod, insomuch that the caburetor becomes fairly indifferent to the metering rod (more specifically the size of the aperature at the needle nozzle interface), and only shows problems if it is way too lean. I think Glenn stated earlier in this forum that what he thought it sounded like ?is that you can go a lot richer and still have efficient atomization? and he is correct, you can run the carburetor very rich and still have decent performance. An interesting side note is conversely if the metering rod is too lean it simply won?t run hard enough past idle settings to hurt the engine, eliminating burned pistons. You don?t have any intermediate circuits to cheat it long enough to run through to the point of overheating the piston.

We do have different sizes and series of metering rods. Most changes are usually related to displacement of the engine only and have little to do with engine modifications. We typically use only one metering rod, from full mods to totally stock and have excellent results.

The ideal way to change the ?preferred characteristics? with a SmartCarb is venturi size. For riders who like a milder hit with a lot of top end we recommend a 40mm for 250-300cc?s, for those who like a lot of torque and a little less top end a 36mm is recommended and for those who like both we offer a taper bore 40/38mm and 38/36mm.

Corey

2011 GasGas EC300
Click to expand...

Seems I forgot to mention: The 38mm SmartCarb is typically the best replacement application for 125-300's that come with a stock 38mm.
 
Jakobi said:
Sometimes I imagine I'm pro! Always riding specific tracks. So what benefits do the taperbores have? How does it change the power delivery? Can you give an example of a benefit/weakness and a track/condition that would highlight this?
Click to expand...

Jakobi,

Our standard size carburetors are already a taperbore in the conventional sense in that we use a highly annular entrance into the venturi. I'm guessing you are certainly aware most slide carburetors have a straight wall section (bell) that leads into the venturi proper, ours does not. We do this to increase laminar airflow along the curved edge leading into the venturi, this diminishes flow turbulence and keeps the air moving straight through the throat of the venturi and under the slide. Based on the curvature of the lead in we are able to "position" the maximum negative value of the signal generated by the low pressure zone around the needle.

The benefit of a taperbore (not to be confused with the keyhole taper others have discussed in this forum, which is top to bottom) is simply to increase the total CFM the carburetor is able to flow. Our "blended" 40/38mm taperbore will pick up roughly 27 CFM, 22% @ 5 inches of water over a straight 38mm SmartCarb.

Where this is valuable is if you run wide open/high gear most of the time or you have a modified engine with a wild exhaust that has moved your power peak up 500 RPM or more. We find that fully modified snowmobiles or PWC's respond best to this type of carburetor. The tradeoff is that the increased airflow (CFM) corresponds to an increase in fuel flow, therefore it requires a full size richer metering rod and fuel efficiency gains are drastically diminished. Gotta feed those ponies.

I don't recommend our taperbores for enduro/woods type racing. Pro open class motocross, open desert racing, snowmobile hillclimbs/drags, yes. Drag bike Lectron replacement, yes. I hope this answers some of your questions. :)

Best Regards,

Corey
 
Sure does. So essentially in laymans terms the taperbore offers similar benefits to a traditonal ovalbore by allowing the benefits of both sizes, albeit it at the expense of some higher fuel consumption when holding it open.
 
Jakobi said:
Sure does. So essentially in laymans terms the taperbore offers similar benefits to a traditonal ovalbore by allowing the benefits of both sizes, albeit it at the expense of some higher fuel consumption when holding it open.
Click to expand...

That's correct, Jakobi.
 
Gasgasman,
Regarding the substantial increase in performance: Are you considering taller gearing to take advantage of the extra power?
 
Well at this point why don't we get a head count of those seriously interested in waiting for the cast production carb. When things firm up on Corey's side as far as production costs and dates, he can give us his best price. Simple.

I for one am in for a straight bore 38mm.
 
Im in for the 38 too , but may be tempted with the bilet version as next year is a long wait , just need a price including shipping ;)
 
Diggs345 said:
Im in for the 38 too , but may be tempted with the bilet version as next year is a long wait , just need a price including shipping ;)
Click to expand...

Diggs,

Please feel free to call me direct at 307-761-1251 Corey
Or Steve 816-835-2505

I think it is important to say that we welcome everyone's interest in the SmartCarb and recognize how vital and important it is to receive endorsement from those who embody our sport and and appreciate and enjoy our products. It is however not our intent to use GasGas forum to market and sell our products. Therefore we appreciate and want to thank GasGas moderators for allowing us to communicate our technologies here and want to encourage interested parties to communicate sales questions directly with us either our website or direct lines.

Respectfully,

Corey
 
GMP,
I'm in for a cast straight 38.
I'm with Diggs: I may be pushed to the billet sooner.
There is an identical thread to this one on "another" Forum and there have been several billet orders over there. With a couple here, we cheapo's sitting on the fence should have lots of irresistible feedback very soon.
 
andoman said:
GMP,
I'm in for a cast straight 38.
I'm with Diggs: I may be pushed to the billet sooner.
There is an identical thread to this one on "another" Forum and there have been several billet orders over there. With a couple here, we cheapo's sitting on the fence should have lots of irresistible feedback very soon.
Click to expand...
Which forum is that ?
 
The orange place no doubt. Easy enough to see whats going on with a search.

Billet vs. cast is not only about cost although that is certainly a major factor, but its also about size, weight and overall refinement.
 
I too am definitely interested in a cast carb when they're available. If I had the money, I don't think I wouldn't just get the already available billet version (Damned medical bills :mad:)!
 
I would like to buy one of these carbs but haven't heard any pricing and/or availability quotes yet from Corey.
 
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