Naluboy

I have two MR 12 3port motors. One runs super the other just the opposite. I know that my setting are on the rich side but the motor still runs very hot 256* to 285* and this is with the body off. I need some neede tuning advice... Thanks!

mtx3racer

is sounds like you might have an air leak

Naluboy

Air leak huh, okay seal the carb back plate fuel fittings, do I also seal the head somehow? Is there anything else or some tricks to getting it right? thanks...

Demetris Taylor

Sealing the Carb and the back plate should eliminate any air leaks if you have them.

Did you break these two engines in the same way? And with the same fuel?

sook

There are many more variables you left out:
What kind of car are the motors in?
Are the cooling fins with the cut through the center getting air flow through it?
Is your two speed shifting? Do you have a two speed?
What plug are you running with what fuel?
Where are you located? (high altitude, low altitude?)
Let people know more about your settings and they should be able to assist you in a more precise answer.

Naluboy

ok, here goes:

Car: V-One RR Evolution
Fuel: Mugen Seiki 20%
Glow Plug: O'donnell 77
Exhaust: RD Logics 1 piece outlaw pipe
Current needle settings: high speed needle 4 3/4 out
low speed needle 3 3/4 out
midrange stock settting (did not adjust)


Characteristics: starts ok with good priming, at full throttle speed is fairly good, transmission is shifting, at idle engine loads up in a very short period and engine dies out, at low speed throttle is very rich sputters alot, temp ranges at this setting from 207*at idle to 285+ after running for at speed for less than 3 minutes. Need more info? I can't figure it out... Any advice will be greatly appreciated. Thanks!

Fisher890

Sounds rich on the low and a bit lean on the Hi maybe an1/8th to 1/4 richer on the Hi but I'd definatly go leaner on the low first. Also what is the length on your fuel pressure line? If you have one that runs good leave that one alone. Sometimes 2 identical motors need a bit differant adj. Get the idle to run good without loading up then adj Hi accordingly.The shorter the fuel pressure line the faster the throttle responce.Don't get too freaked out on temp either some motors need to run hotter then others. Hope this helps

ziggy12345

Deffinatly rich on the low side and lean on the high

If the low end is rich the motor will idle ok and there will be a large volume of mixture in the crank. This takes time to clear into the cylinder, about 2-3 secs so as you apply the gas the mixture in the cylinder will get leaner and leaner.

To adjust your low end let the car sit at idle and apply full gas for 2 secs and release. If the engine returns to fast idle then drops to slow idle the low end is to rich.

Lean out the bottom end then try again until the engine returns to fast idle and stays there. Adjust the idle screw to reduce the idle revs down.

You now need to richen up the top end. Open 1/4 turn and try again

Another cause of overheating is to low a compression ratio. check the head clearance.

Cheers

Naluboy

Hey all thanks alot for all the advice. I'll definitely try those suggestions. So far I sealed the carb and the back plate tried running it but still only so so results. It doesn't run those high temps anymore but definitely need to be fine tuned. Once again thanks for your responses. As we say in Hawaii~ MAHALO(THANK YOU)!!!