APT SmartCarb

[flyingbob]

The new billet carbs will have a overflow drain. I understand it's only a problem if your bike is upside down for a while ; it can flood. They are going to send the revised parts for the one's they have already sold.

Very short while, and the bike doesn't need to be upside down!Those tubes flow a lot of gas. That is the only issue that isn't operator related in my opinion. When it's corrected the carb is golden! I ordered another one...

 

[Idacurt]

Are they going to offer a cast 36mm?

 

[lankydoug]

Add in that it is altitude adjusting which is huge for me.

I put once adjusted it's not temperamental since there was feedback that it could be ridden through extreme altitude changes without adjustment. I didn't find any proof that after extreme changes of altitude that the air fuel mixture was still ideal. To me this is a minor point because according to feedback one or two clicks of the knob could solve this. I was being careful not to overstate the benefits.

From my perspective this carb will solve many 2t carb issues and save me from buying an oversized fuel tank that all reports claim fits poorly. If I can ride in MO to the CO mountains without bringing jets and messing with the bike it is worth the money on that alone. Add to that an increase in throttle response, top end power and 20% better fuel economy ie. 10 more miles to a tank, buying a SC is a no brainer.

 

[wallybean]

I agree Doug and altitude adjustment is more than being tempermental. When a ride has more than 6-7000' in altitude change any traditional carb is not going to handle that without jetting changes or living with a poor running motor at some point. Apt has based much of their research and development around the Pike's Peak hill climb with outstanding results and that is what I base my assumptions around. It is about the most important factor for me. I do very few rides with less than 4000' of elevation change. All the rest of your points are icing on the cake and have me slathering at the mouth.

 

[Gotlabs]

Just saw on FB that they are taking orders for the cast version for $375.

 

[huskybear]

Well, mine wasn't as 'plug and play' as yours! I had to remove the subframe to get the APT carb into position. The outside to outside measurement of the spigots (engine to air boot) is 75mm for the Mikuni and 94.5 for the APT. The body width of the carbs (end of carb rubber to end of air boot) is 53mm for the Mikuni & 67mm for the APT. Once I got the carb positioned in the intake boot and the air boot, I had to force the subframe into position while the air boot flexed in a bit. There aren't any noticeable bulges or compression wrinkles in the air boot. My throttle cable housing is a tad short so I will see about rerouting that tomorrow. I get rpm creep at full right turn.

The bike fired right up cold without the enrichment circuit opened up. Idled high so I backed it down and went for a little spin. Pulled really well but I didn't hammer it, dark was fast approaching! Seemed kind of lean so I took john01's que and turned the adjustment 3 clicks rich. While I was in the process of getting the needle engaged in the adjuster (you have to open the throttle wide open while turning the external screw to get internal components to 'mate'), the slide or spring released out of a 'bind' and subsequently my idle fell to nothing when I restarted the bike after the adjustment. The bike ran much better after the adjustment but I didn't give it much of a test in the dark!

I rode the bike prior to switching the carbs so I could get an immediate seat of the pants comparison but I was banking on that 15 minute swap! Oh well, I'll fill everyone in tomorrow! It did seem to pull harder ( with more authority ) through the gears as well as at lower rpm in a higher gear. More to come.

Did you have any issues with the airboot rubbing on the shock spring after installing your smart carb? I am wondering if I will have to get creative with a heat gun when I get mine for my wr144.

 

[flyingbob]

Did you have any issues with the airboot rubbing on the shock spring after installing your smart carb? I am wondering if I will have to get creative with a heat gun when I get mine for my wr144.

No issue there!

 

[Phoenix]

Question for the APT guys, how much shorter in overall length do you think you can make the cast version as opposed to the existing billet ones?
I'd like to preorder but I'd like to know that it will be relatively close in length to my TMXX. Longer carbs cause the air boot to rub on the shock spring and that's not good.

Thanks!

Saw this over on the Gas Gas forum in regards to the dimensions. I'm really thinking about one of the cast versions for the new Gasser.

Currently the billet SC dimensions for the 36-40mm top pull SmartCarbs are; 3.75" (95.25mm) venturi end to end and 7.025" (178.4mm) top to bottom, same width as a Keihin or Mikuni.

There are several features of the SC that are critical to it's performance. The area under the slide is necessary for signal stability to the metering rod and fuel lift. The SC venturi features are operative both top to bottom and end to end; signal strength for the former, laminar flow and signal projection from the latter. As such, form decidedly follows function in this case and until further research can be attained we have little wiggle room to alter dimensions, especially venturi end to end.

So....we are trying to shorten the flange sections a little on the cast carbs (these are yet fully proven as we are just receiving our first samples) by a half an inch, which will put them within a quarter inch of a PWK striker. The other dimensions will remain the same as the billets (same as keihin and mikuni's more or less). If they perform as good or better then that's likely where we will wind up. They will also be a pound or more lighter. Realistically though we are finding little resistance from oem's on dimensions, they are only interested in performance and emissions. Possibly new bikes may be more accepting of the SC's added length.

 

[Blair7]

The new billet carbs will have a overflow drain. I understand it's only a problem if your bike is upside down for a while ; it can flood. They are going to send the revised parts for the one's they have already sold.

Does this mean we should expect a package in the post or do you have to approach them about it? Where did you hear this if you dont mind me asking?

 

[john01]

I read it over on the GasGas site. I think they will be asking us to send the carb in so they can do one part of ther upgrade. I'm just going to wait until they get the parts and call them about it.

 

[TROFFER88]

Apt a asking people to post results on Cafe Husky over on the Gasgas forum so he can avoid paying a sponsor fee is complete BULLSHIT. Hey Corey if you have no problem asking $775 -$875 for a dirt bike carb then you should have no problem paying for advertising like everyone else


If there is someone on here who also posts on the Cafe Husky forum, could you please post this response to a similar question on the husky site. Glenn will no longer allow me to post without buying a sponsorship

 

[firebolter]

Here's a list I created from reading the SC thread on the GasGas and CH forum.

List of benefits;
No jetting required only external adjustment
Better throttle response with no circuit transition dead spots
No external vents to suck trash & water in to the bowl
Once adjusted it's not tempermental
Increased performance claim 10% across the board
Increased mileage 10-20% (making my 2.6 gal WR250 tank seem like a 3 gal.)


Down side;
Throttle cable is tricky to hook up
Can flood engine when inverted (check valve update is supposed to fix this)
Longer carb body is tight fit in air box designed for Mikuni carb dementions


I can edit my list if anyone comes up with other points. I kept the list to performance issues only because cost is subjective and a personal choice.

A conventional carb can also flood the engine when inverted and I've often wondered how much fuel is dribbled out of the vent tube and wasted while riding in rough terrain.

And temperature changes are compensated for as well.

 

[Motosportz]

Very short while, and the bike doesn't need to be upside down!Those tubes flow a lot of gas. That is the only issue that isn't operator related in my opinion. When it's corrected the carb is golden! I ordered another one...

I flipped my bike upside down going off a trail first day I tried the APT, no issues. No flooding and started right up.

 

[Motosportz]

BTW did another 53 miles in the gnar yesterday. This area has it all, tight nasty single track going straight up and straight down and some more open quad trails for connectors. This is on my newly installed 165 kit and KTM 200 Doma pipe. Best motor ever for me, period. Gobs of liquid power everywhere. I am in love.

 

[Motosportz]

So as reported IMHO the APT carb is the real deal and does in fact bring many cool things to the table.

- Far better throttle response
- increased HP across the board especially bottom and top.
- EZ "jetting" changes

I did find the choke circuit seems to rich for my needs. Will not start without it cold but seems to need some throttle to start it with the choke on and then needs turned off real quick. I also do not like the throttle cable retainer, had many issues with that.

I am done testing and going back to the stock carb for the next ride to see the difference on the frankenmotored 165 (FBF ported cylinder bored to WB165, Domes KTM 200 pipe, reeds on "low" setting).

Vinduro has been kind enough to offer me his new Lectron car to test so when that gets here i will evaluate that and see whats up. Then we will have 165 results for the stock carb, APT and Lectron. Fun stuff.

Thanks all.

 

[john01]

Great job Kelly and I look forward to your stock carb and Lectron carb. Ok Walt your turn .

 

[flyingbob]

Here's my quick fix for the throttle cable retainer position. I wouldn't have thought that it would rotate under the spring pressure, but it does. There is a threaded hole to receive a screw, but that is not supplied, and maybe not a good idea anyway. I reshaped the top of a cotter pin. No worries now!

 

[wallybean]

So as reported IMHO the APT carb is the real deal and does in fact bring many cool things to the table.

- Far better throttle response
- increased HP across the board especially bottom and top.
- EZ "jetting" changes

I did find the choke circuit seems to rich for my needs. Will not start without it cold but seems to need some throttle to start it with the choke on and then needs turned off real quick. I also do not like the throttle cable retainer, had many issues with that.

I am done testing and going back to the stock carb for the next ride to see the difference on the frankenmotored 165 (FBF ported cylinder bored to WB165, Domes KTM 200 pipe, reeds on "low" setting).

Vinduro has been kind enough to offer me his new Lectron car to test so when that gets here i will evaluate that and see whats up. Then we will have 165 results for the stock carb, APT and Lectron. Fun stuff.

Thanks all.

Ok Kelly, great stuff and now we all have to wait for ours to get here....... I guess I do want to try it so I can compare it with the two pipes I have. Send it if you can although my riding will be strictly around the place unless it warms up over in Butte at Pipestone.

 

[Motosportz]

Ok Kelly, great stuff and now we all have to wait for ours to get here....... I guess I do want to try it so I can compare it with the two pipes I have. Send it if you can although my riding will be strictly around the place unless it warms up over in Butte at Pipestone.

Will send sometime this week. Was going to send to Motomarc36 as i thought a pure MX test would be good and did not think you wanted to try it but will send to you ASAP.

 

[Motosportz]

BTW i did find out what the mysterious white smokeout was on my bike. When i get on my bike like on a big hill it smoked a white smoke like crazy, had a weird smell and would fog up the whole area. Turns out it was the older notoil filter oil coming off my filter in large quantities and gooing up the carb and going through the motor. Bike still ran perfect but was a fog machine. Problem identified.