fast9

I now this is a somewhat common problem, but I'm trying to remember the solutions. I have an inverted mount Magnum .91 4 stroke that will not idle without the glow driver on it. It has a OS F glow plug(tried a new one). The tank is slightly higher than the carb, but not a lot. I've wasted a lot of time chasing the low speed needle(after the high was set), and nothing really helps. It will idle for about 10 seconds at best, then die. Compression seems good, but not positive because this is the first and only four stroke I own and I have nothing to compare to. Will an idle bar glow plug help? Different heat range? Idles great with the glow driver attached.

w8ye

My Feedback: (16)

You have to use an OS "F" plug

On the low speed screw you must move it in small increments or you will chase your tail

TedMo

If It's new it probably isn't broken in. What does it do when you idle then come up quickly to full throttle. if it quits immediatly your idle is set too lean. If it gurgles and slowly comes to idle your too rich. Probably needs more break in time. How does it do upright?

jay2000dakota

If its new give it some more time to break in, four strokes tend to need alot of time. How much nitro are you using? (20% gives a good idle for me) If all else fails try. on board glow. On board glow solved all my problems with idling.

fast9

I bought the motor used, but I am unsure of the run time. Currently running 15% nitro. It' mounted in a plane right now, but I am going to pull it out and put it on a stand to try and figure this out.

w8ye

My Feedback: (16)

Check the intake manifold bolts where it fastens to the head?

st_dysan

My Feedback: (21)

If its not a break in problem and it is a fuel tank level problem, try an Iron Bay regulator. It goes between the fuel tank and carb and, from what I've expienced, reduces the loading up of the carb from siphoning from the higher fuel tank. It has solved my two invert problems on two different 2 strokes. Both mounted in warbirds, p-47, and hellcat). PM if you wanna give one a try, I think I bought like 4, and have only used two.

w8ye

My Feedback: (16)

Iron Bay's Web site doesn't work correctly

Iron Bay Model Co
3301 Chapline St
Wheeling, WV 26003
304-232-7511

bkdavy

My Feedback: (1)

I have two of these engines, one inverted, one sideways. They are difficult to tune. They come with the low speed needle set VERY rich. The way I finally got them tuned properly was to keep leaning out the low needle. I think it actually had close to 3 turns from the factory setting. After each adjustment of the low end, you must retune the high end. If you have turnied the low speed needle in 3-5 turns total and its still not getting better, try the other direction. You want to make the adjustements about 1/4 turn at a time, so it might take a while.

If you can get to the low speed needle with the engine running (its behind the engine, so it can be done), you can adjust it while the engine is running. As you lean it out, the engine should get smoother on the low idle. Don't forget to check the high speed after adjusting the low speed.

Brad

twn

I had a similar problem on my magnum 91. but mine was not inverted. I installed a perry pump. the standard vibration type. Helped a lot. Also with mine if any of the fuel line became pinched (even slightly, so slightly it isn't noticable...) mine would die. Lots of dead sticks for me... Once I routed the lines so there wasn't any sharp turns and put the pump on it was great!!

Rudolph Hart

Yup give me a price please.I'll have the lot,including the one's your're using now if you don't mind