Huh,i have the Ultra MBX Pro,with the .26,yeah they can be finniky espessilay if you’re pull starting,be sure your glow ignitor is fully charged,be sure the plug glows cherry red,then remove the body,put your finger over the tip of the pipe (stinger) and pull until you see fuel get right up to the carb,dont have the ignitor on it during this procces,all we want to do is get the fuel to the carb,when it’s there STOP,then put ignitor on and try it,i have a starter box for sale if you’re intrested.Mail me if you have any r/c questions at all phone 607-754-2901 my real name is Joe,i have free long distanse ,so if you mail me your # and live in the US Canada or PurtoRico i can call you and guid you through any probelems,i’m 34 yrs old and been racing since i was 11,i have 6 nitros,Mugen Sekie,on road,MBX,Traxxas nitro 4-tec 3.3 on road,Serpent 710,Hpi ,and a Traxxas Jato 3.3.

the only way is to get it to warm I use those hand heaters that they sell at the check out at wall mart and warp it in them for a little bit just on the head (hot hand’s ) that’s the name we did the annual January 1st flight it was 8 out there and it worked great and after it worker great to for me

Warm up the cylinder head. Leave the car with the body off on the floor of your automobile and run the heater then take an old clean sock and put it over the head.
Once it starts tale the sock off and let the engine heat up on its own, bump the throttle a little. Let it idle for about 3 minutes and if the carb is all tuned in have fun.