I bought an ofna ultra mbx in december and so far i love it it's my first nitro car. While i was running it today i noticed it was running hot so i richened it some and it stayed hot. I shut it down let it cool and reset the carb to factory settings then ran it again but its still hot and i know its not lean because i have fuel spitting out the exhaust. Whats wrong and what should i do?

what do u mean its hot i mean of corse the darn thing is gonna get hot it should be around 250 degrees. Its gonna be hot to the touch.

}{unter

well ive been doint the spit test and the spit is boiling off in a couple seconds from what ive read and been told it should only slowly simmer off

pending on temperature of the air all nitro engine will get hot. the heat sink can onyl do so much. i know when i run my trucks and cars in the freezing cold i can touch them for about 5 seconds without getting burned but in normal temps it will get much hotter. 2 sesoncs sounds like it is runnning hot although some engines are designed to handle more heat. ask around and see what people with the same engine are saying it may be normal

if it takes about 2 to 3 secs its around the right temp just make sure u see smoke out pipe

}{unter

wow my engines must be running very cool. it takes 10 seconds for my spit to sizzle away. either thjat or i just got really heat resistant spit lol

Mine took about 2 seconds to boil-off then about three days later I couldn't get my engine to start. I sent to the factory so they could have a look at it... come to find out I overheated the engine. What % nitro do you run? I would try a nitro fuel with more lubrication. Maybe your not getting enough lubrication and everything is creating more friction than it should. Talk to the guys at your local hobby shop and have them recommend a fuel for you to try. Hope this helped. good luck.

u can buy racing fuel which contains more oil, and will help cool better.

thanks for the info guys iv been running 20% then yesterday i tried 15% with a much higher oil content. i think i have an air leak though i was reading an artical last night on rc car action.com and it described my problem and explained how to check for and fix a leak.

im running 10% with 18% oil. i like my engines to last long. even though i only run 10% the engines still produce lots of power.

yep but not like my 20 %


}{unter

hey well i think i got it fixed. i pulled the motor and pulled it apart and resealed every thing and ran it yesterday. It seemed to be running great for about 45 mins until i through a dog bone on a gnarly crash off an embankment and did about 10 cart wheels!

yeah and i like my 20% too

Also, you could be running to lean on the bottom end. That would cause you to get very hot at mid to low idle and with a rich high end, you would be seeing a lot of smoke and oil in the pipe.

Does that buggy have the .25 force engine? If it does, you wont be able to keep the temps under 300 and still make good power because they use garbage material in their engine manufacturing, why do you think they are so cheap. You probably cant get it started after it dies either huh, they have a bad hot start problem because the fuel boils in the crankcase and carb. All you can do is like you said, seal it up with air seal you buy from the lhs all around the carb and maybe try using a less percentage of nitro. I had the .25 force engine and it ran hot all the time and lost compression after 2 gallons of 20% running rich too, in my opinion the .25 engines suck and they are a ripoff but I hope you have better luck than I did. Dont mean to rip on your buggy just telling it like it is.

hey kyokai2, whats with the nickname...are you into marshall arts...just wondering, cause I study OKINAWA GOJU-RYU KARATE.sorry for getting off subject guys. :stupid:

no its not a force .25 its a .21 and i think i got it back to the right temp. i havent had a chance to really test it though. im almost through the first gallon of fuel so i hope mine lasts a bit longer. if not at least ill have a good excuse to give the ol' lady when i spend the mony for an upgraded motor.