mtthem

I just got a new crt .5 and dropped in a .12tz(p). Over the past week ive been breaking in the engine. I havent touched the carb settings from the factory(every needle screw flush), I also left out the carb insert. The engine was a pain to start at first, i had to use 14.4v to get the engine past its pinch (which i hear is normal). Now that the engine has started i ran 1 tank at idle to get up to temp, let it cool down and ran a 2nd tank and putted around a parking lot, not going past 1/4 throttle. On the 3rd and 4th tanks i tried driving with a bit more throttle but once i get to 1/2 throttle the engine cuts out. The engine was blowin a lot of smoke so i figured it was too rich so i leaned it out (high speed needle) a 1/4 turn each time it stalled until i reached 2 full turns. fearing i was going to run too lean on a brand new engine i stopped running the engine to further investigate the situation. also, after each time the engine died a tipped the car to see if there was any oil in the pipe and there was quite a bit every time, ive never had this problem b4. has anyone else?
Is it also nessary to run the carb restrictor? ive run many engines b4 and ive never needed to use the carb restrictor.
Could the shorter pipe on the crt effect the engine?
Should I be adjusting the mixture screw? I never liked messing with the low end or mix screw.
(using a p6 plug and 30% nitro)
Any help is appreciated.

Bax

My Feedback: (11)

First, we'd be very skeptical of your "break-in" method. We NEVER idle an engine more than a few seconds before we start to drive it. Idle it for a tank or more and you'll have a short engine life. You must DRIVE the engine! We run the engine up and down the parking lot, going up to high throttle and back down, gradually leaning the high-speed needle as we go. It all depends upon how the engine sounds and performs. That's the key. Temp is irrelevant until you have the engine properly-tuned. Then temp can tell you if something's going wrong, but it's not a key to tuning. Use temps to tune your engine, get short engine life.

Adjust the needles as necessary. You can't get a good low-end tune until the high-speed needle's properly-adjusted, but you can start to adjust it to help with idle and midrange.

If the engine's quitting at 1/2 throttle, then it's likely much too rich on the high-speed needle and the low-speed needle. The "factory" settings are only very gross starting points, and nowhere near the final adjustment point. That, you have to find while running the engine.

mtthem

Thanks for the reply but i thought that when u get a new engine the cylindar and housing are not perfectly seated properly and if u were to run it at high throttle this would not allow the metals to seat correctly or even worse you could score the cylindar and loose compression. Is this true?

Bax

My Feedback: (11)

Non-ringed engines cannot break in properly unless they get up to full operating temperature. You need to run them up. If you idle the engine, it will never get up to temperature, and you'll never get it properly broken-in. What happens is that the piston gets "rammed" into the taper of the cylinder and eventually gets beaten to a looser fit. Then, when the engine is actually allowed to run up to temperature, the fit will tend to be too loose. Idling a tank or two may be a fast way to "break in" an engine for racers, but it will not last very long. For "Gung Ho" racer types, they don't care if a piston/liner set lasts longer than a few races or a race weekend. The engine did its job. However, for longevity, an engine must be run up to temp and speed.

Use a good-quality fuel with no less than 18% oil content, and you'll find that a properly broken-in engine that's been properly-tuned will last you quite a long time.