APT Smart carb, for CR250.



85 replies to this topic
  • DHS_sponsored

Posted December 27, 2012 - 10:24 AM

#1

Right, alot of us swap out the TMX for PWK's............really common mod.

So, has anyone here, or that you may know, bitten the bullet and tried one of these Smart carbs on a 02-07 CR250.

I have been keeping an eye on a few different forums, specifically the Gas Gas riders one that is 50+ pages, and general consensus appears to be great.

I am set on ordering one (I would love 2 though, one for my 500 build too) to go on to my 06 CR250, but I am opting for the cast version, due, May time, 2013.

  • shrubitup

Posted December 27, 2012 - 10:29 AM

#2

wait for cast model.

  • pieplatesnductape

Posted December 27, 2012 - 01:07 PM

#3

wait for cast model.

+1 looking forward to it.

  • c-slak

Posted December 27, 2012 - 01:13 PM

#4

Once the cast version is out I will be trying one too.

  • DHS_sponsored

Posted December 27, 2012 - 01:18 PM

#5

You can pre-order now, $375 on the powerapt website, they only have the 38mm cast versions available at the moment, but that will suit 90% of mx/woods applications anyway.

  • seanmx57

Posted December 27, 2012 - 05:06 PM

#6

Do you think the 38 is enough for the 500?

  • DHS_sponsored

Posted December 28, 2012 - 03:24 AM

#7

I recon so, they say that these carbs 'flow' as well as a bigger carb at wide throttle openings.

It really depends what you are doing with the 500, there are plenty of people out there running 39+mm carbs, that would be much better off with a 36 on there, and visa versa too.

I think a 38 will be fine for what I am doing, which is purely motocross (In the UK too, where our tracks are normally smaller than yours and alot of hard pack)

  • seanmx57

Posted December 28, 2012 - 02:39 PM

#8

I hear you. I don't need more top end power on the 500 for MX........

The 250 on the other hand, a bit of rock and roll....... Oh yeah I'm getting old, a 38 would be fine. I read thru those 50 pages, looks like next summer will be a good one :)

Do you know if there are options like the taper bore on the cast units on special request?

Edited by seanmx57, December 28, 2012 - 02:41 PM.


  • DHS_sponsored

Posted December 28, 2012 - 03:32 PM

#9

I think its going to be straight 38's initially, with the 36 to follow, then maybe the taper bores after that (if at all).

Hopefully someone from APT will see this discussion and maybe chime in.

I tried a 39.5 on my 250, and hated it, its was 'too much' of a carb for it, i didnt mess long with it though, maybe it could have been better, but i will i dont need more than 38 for it.

I know its not directly related, but the moto gp 125s (pre moto3) used primarily 36mm carbs, they flowed well enough at huge RPMs and 50+ bhp, a 250, or 500, is going to 'suck' harder through that same carb, getting what it needs, hence why anything from a 125, to a 500 can use a 38mm carb.

My CR134 i used to run, with an identical carb to my 250, wanted main jets in the region of 185-190, bigger on a boggy, or sand track. yet my 250 only wants 165-170. i tried that 39.5 on the 134, same case, hated it.

I see that quite alot of people use a bigger than 38mm carb on the 500's, but that is normally for drags, dunes, or ice racing. With stock, or near stock porting, the engine just does not require a bigger carb, if you are going to go to 198 degrees of exhaust duration, with a super duper 'rev' pipe, then a bigger carb may be the ticket.

Now I havent done a great deal of looking, but running an un-modified carb manifold, with anything bigger than 39mm on a 500, doesnt seem worth it, because the manifold is the restriction in the tract. The same applied for my 134 using a rad valve, its x-sectional area i dont think was ample enough to suit the 39.5 carb.

a 38mm carb has a x-sectional area of 1134mm

a 39.5 is 1225, thats 91mm difference. Thats around an 8.5% increase, doesnt seem much really, but it does make a difference. You may gain in top, but lose else where, that may be a good thing though.

My 500 is having the port durations raised a bit, a PC pipe, a 39.5mm PWK plus a programmable CDI unit, head mods, and a Cr250 chassis (or a 38mm smart carb if i can afford another at some point).

My aim is to TAME the power a little, reduce some bottom end/hit but increase the upper a bit. I am like 145lbs, and ride primarily hard pack tracks (and i mean laying rubber on to it hard!!) We dont get many 500's over here in the UK, and I want to pull some holeshots on it, and when given the chance/track, rape every other bike on it, up the hills, just to show people what a 500 is capable of.

I come from 125's, and 250's, I ride a 250 quite hard. I know a 500 doesnt want to be revved hard,which is why I want one, i rev the 250 pretty hard, because, even though I am crap on a bike in the grand scheme of things, i want more of a spread of power, but not a 4 stroke. Its hard to explain, i am a bit 'point and squirt', and find that I clutch the 250, when i feel that i shouldnt be, but when I dont, it doesnt do what I want it to do. It is an awesome motor, and pulls well all over, its far from stock, but not in a 'top end only' manor, it has a far better spread of power than a stocker does, and is really really good on hard pack for a 2 stroke, smooth!

  • seanmx57

Posted December 29, 2012 - 01:30 PM

#10

There is no place for sensibility with CR500's, more power is mandatory.

Do you remember if the length of the smartcarb is going to be the same as a PWK airstriker? like the ones that came on 2000 CR250's.

Edited by seanmx57, December 29, 2012 - 01:51 PM.


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  • houseofthumpers

Posted December 29, 2012 - 08:24 PM

#11

I've been doing alot of research on this carb and I i've found a bit of info on it. Everything i have read said It's great and worth every penny. here's all my sources.

Their website: http://www.powerapt.com/smartcarb.php
Their prices: (They sell out constantly so you have to pre-order) http://store.powerapt.com/
GasGas forum reveiw: http://www.gasgasrid...ead.php?t=13471
Thumpertalk reveiw: (even APT shows up to talk about it) http://www.thumperta...__hl__smartcarb
Dirtbikeworld: http://www.dirtbikew...ead.php?t=96980

  • DHS_sponsored

Posted December 30, 2012 - 02:48 AM

#12

Length wise, i think 93, or 94.5mm long, cant remember, the 2000 PWK is 91, so pretty close.

  • dirtracker

Posted January 06, 2013 - 09:35 AM

#13

Is this carb in existence or a fiction looks like a scam to me!!!! In there website I only see a crude carb made from a billet aluminum in a side view without any data,specs,diagrams.They dont even have pictures of the internals looks like there is a black art or some sort of magic engineering involved.
Even the pre order form is not verified or secured I smell something fishy huh!!!

Edited by dirtracker, January 06, 2013 - 09:50 AM.


  • ben williams

Posted January 06, 2013 - 09:45 AM

#14

There is alot of talk on Cafe Husky too about the Smart Carb. Also the same design wich has been around longer is the Lectron, and is also less expensive.

  • shrubitup

Posted January 06, 2013 - 10:19 AM

#15

Is this carb in existence or a fiction looks like a scam to me!!!! In there website I only see a crude carb made from a billet aluminum in a side view without any data,specs,diagrams.They dont even have pictures of the internals looks like there is a black art or some sort of magic engineering involved.
Even the pre order form is not verified or secured I smell something fishy huh!!!


guy I know has one on his 300KTM so they are real.

  • dirtracker

Posted January 06, 2013 - 10:34 AM

#16

guy I know has one on his 300KTM so they are real.


Still just not convince me to buying one even if he sells it for 200 bucks at his website!!!!

  • mynewcr250

Posted January 06, 2013 - 10:54 AM

#17

take off the tin foil hat dude

  • shrubitup

Posted January 06, 2013 - 11:09 AM

#18

Still just not convince me to buying one even if he sells it for 200 bucks at his website!!!!


Powersports plus dot com has a 10% off sale and free shipping over $149 purchase. Picked up a '00 CR250 Keihin PWK airstryker for $170 shipped. :banana:

Use code get-what-you-wanted thru 17Jan13 only.

  • DirtRider500R

Posted January 06, 2013 - 11:21 AM

#19

The Smart carbs seem to be the "replacement" for the Lectron. I'd definitely wait for the cast version to come out.

This is what I'll be running on my 86 CR585: http://www.lectronfu...carburetor.html

  • dirtracker

Posted January 06, 2013 - 11:24 AM

#20

Powersports plus dot com has a 10% off sale and free shipping over $149 purchase. Picked up a '00 CR250 Keihin PWK airstryker for $170 shipped. :banana:

Use code get-what-you-wanted thru 17Jan13 only.


Yes TNX I have an 03 yz250 carb tps connected on my 05 CR250.





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