RaveCrusader

I took my two redcats out this weekend with my son for some backyard bashing. He has the shockwave which has worked great until this weekend. For some reason after warmup about halfway through a tank of gas the engine will to the best of my description "bog" down and lose almost all power to the point it can barely make it back to us. If we turn it off and then immediatly restart it will be fine for a few more minutes then do the same thing. I have tried tuning, but it does not seem to have an effect this issue. Anyone have any ideas..we have had them a few months and ran through maybe 10 tanks of gas through it.

nitrosportsandrunner

hard to tell if its a mid-tank lean....

when you turn it of and then restart it, do you add fuel to the tank?

Dads like rc too

Also if this only happens when the engine warms up it may be a compression issue.

RaveCrusader

I did add fuel to it to top the tank off..it was about half full. My son also noticed when he would turn the rpm's would start to rise and the engine would regain some power then when he would go straight again the same thing would occur.

RC Hobby Starter

Had the same issue with some customers it was a mystery to myself and to Redcat it absolutely is a compression issue! The guys that had the trouble were running them in very dusty conditions which we chalked it down to the cause of the issue.

Try removing the ring under the head it may add more compression but I honestly think your engine is pooched, you can try doin a compression test as well.

Redcat will replace the motor for half the cost of buying brand new through the replacement plan.

RaveCrusader

thanks for the feedback, I enjoy this community is so active. Well that stinks..yea, the engine replacement program is not bad..and we mostly used it in dusty area (a series BMX ramps near our house, completly off road).

nitrosportsandrunner

hard to say for sure, but if refilling the tank solves the problem then its the "mid tank lean"

I cant say I know for sure what causes that, but Ive seen it with models Ive had before. A good tune at the start becomes lean as the fuel in the tank hits 1/2 to 1/4.

With any nitro issue, I always look for leaks to start with. A bad tank lid gasket, carb seal, exhaust gasket or any other gasket for that matter can affect the motor's ability to suck in fuel.

Truely, a small thing like a poor gasket on the tank cap can cause issues.

If the motor can be refired after refueling...and the power is always good the 1st 1/2 tank, then Id think the motor is sound, and the issue is elsewhere.

How does it feel to pull the motor over? If compression is low and causing the issue, you can feel it just by pulling the motor over.

RC Hobby Starter

I absolutely agree to check for leaks before jumping to conclusions! The issues my customers had were not mid tank lean or leaks but certainly check before!  like nitrosportsandrunner suggested you can do a compression test by simply turning over the engine and feeling if there is compression, or if you want to be absolutely sure you can go into more detail by actually opening the motor and pulling out the pinch and piston. you shouldn't be able to push the piston all the way to the top of the sleeve! if you can the motor has no compression. I only suggest doing this as a last resort and if you have experience tearing down motors.

Dads like rc too

Also to clarify my compression post, what I meant is a loss of compression when the engine heats up. This happens to nitro engines when they're on the way to the nitro junkyard in the sky. What happens is as the engine heats up, the sleave expands and compression is lost. The engine will typically start up fine and run fine for a minute or two until the sleave starts expanding. The expansion happens in any engine, but an engine that is worn will not tolerate it. The engine will begin to bog down under higher rpm. At low rpm it will seem to run fine, but as you increase the rpm and accelerate the engine will sound like it just ran out of fuel. This is what's called "falling flat on it's face". When the engine is cold it will have a decent amount of compression when turning the flywheel by hand, but compare it to a good engine and you can tell the bad engine has moderately less push through the stroke.

RaveCrusader

well I took it out yesterday and ran through a tank of gas on the pavement, no dirt, dust, etc. It ran perfect through an entire tank of gas. No issues and I could not be happier. I guess I will keep an eye on it and self diagnose if it happens again. I tried the wd40 trick to check for leaks by spraying around the engine after warm up, nothing. The only thing I can think of is it may be the gas tank seal my not be seating properly.  I will be back if it continues to happen.

RC Hobby Starter

Well i'm glad it wasn't the same situation that Iexperienced we tried everything to get these engines to run properly but we had no luck!
Cheers