New GX40 Gasoline engine
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TOPIC: New GX40 Gasoline engine

Re: New GX40 Gasoline engine 6 years, 11 months ago #337

  • whiskey29

I am having a bit problem with the engine. (prop master airscrew S2 11x6)
I have done the break in.
I have also manage to tune the low end needle, up to a point where it wont go leaner any more ( dies when advancing throttle).

How ever I am having problem with the mid range and low range.
At top end, its fine and very strong,
but idles and mid range many times it sputters, like the glow is too cold.

If I put a glow driver, its fine and doesnt sputters.

Should I change the glow ? Or do I need to reduce compression (may be our fuel here is not having high octane) ? I did mix new fuel to no effect. Please note that regular castor is the only thing we have here and what I used.

At this point, this engine is flyable, but not comfortable with middle and lower throttle setting, like landing.

Thanks in advance

Re: New GX40 Gasoline engine 6 years, 11 months ago #338

  • goldenduff
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I am by no means an expert but sometimes ensuring the basics are right is a good start!

Try a new glow plug- might have suffered when the engine was bedding in. If that doesn't solve the problem having a spare glowplug is a sound investment!

Maybe the low end needle is too lean? Try opening it up a little.

I have heard that the oil/petrol mix needs a couple of weeks to mix well.

Do you have a spinner? The additional mass might help low end smoothness.

I have one of these engines waiting for use (2small children so very little time at the moment!) so I will be monitoring this thread with interest. Good luck.

Re: New GX40 Gasoline engine 6 years, 11 months ago #339

  • hllywdb
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How many tanks of gas have you run in it? I run through a couple of tanks on the ground, then break in the rest while flying. I leave the idle high enough to keep running, then each flight it ends up idleing higher by the time I land. I then turn it down then fly again. As they break in the idle and transition gets better and better. Don't try for a perfect idle until it's broken in or you will just get inconsistent running.

Re: New GX40 Gasoline engine 6 years, 11 months ago #340

  • whiskey29
Hey guys. THanks for the replies :)

The low needle was leaned to the point it will die when accelerating, then richen and as long as the glow driver is on, it will transition nicely, but without it, the engine sputters, but did reach the top end.

May be it needs a lot more breaking in, I did ran it for two 8oz tanks on the ground and have only flown it twice since,
I will fly it this coming sunday, its just that since it uses little fuel, the flights become long and boring haha.

But I will try the new glow plug first.

Any way, the neddle is very very sensitive, one or two click would get it rich from peak, and if I give more, it will sputters on full throttle. By saying sputters I meant it seems that the engine did not fire once every a few revolutions. Its like every half a second or so.


Re: New GX40 Gasoline engine 6 years, 11 months ago #341

  • Charley38
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I suspect that you have the low spd needle set too lean; would suggest that you richen the low spd needle a bit & then set the high spd needle for a rich two-stroke at wide open throttle (WOT).

Here's a link to a GX40 thread on RCU:

Last Edit: 6 years, 11 months ago by Charley38.

Re: New GX40 Gasoline engine 6 years, 11 months ago #342

  • whiskey29
Hi CR,
thanks for the suggestion, I have read a lot of post about the norvel on rcgroups :)
Anyway, about the low speed needle,I will try it again. May be you can give me a suggestion where to start based on your engines, like how many turns for the low speed from the closed position at closed trottle.

But say if I set it too lean, the sputters go away if I leave the glow driver on.

I didnt have a chance to ran it last weekend, I have just mixed a new batch of fuel this time with Castrol M. I am also purchasing a maxima castor 927, a castor oil which will arrive next week.
I will try again in a few days

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