Hi

I need some help. I have a bme 44cc that I can not run properly below 1800 rpms. I have read that I should not expect anything better for the first 4-5 gallons, so I think I can live with it. I adjusted it to fly with an idle around 1900 rpms, but when I set the gas down for landing, it tends to quit, in fact, I have two dead sticks close to the runway. I am getting nervous about this idle. The carburetor opening is inside the cowl, only the back part with the adjusting screws stick out a bit ( no so much). The engine runs great while in the air and on the ground, the problem is only when landing. So I richened the idle a bit, and set the "idle" at a little higher rpms , what else should I do? Is this situation normal during the breaking in of a bme engine ? Also, I set the plug´s gap at max allowed, so I am getting a good transition now, but missing some rpms at high end. ( around 6900 rpms mejzlick 20*10). BTW, I am new to gas, but following everything as per the manual.
THANK YOU.

I would lean the low end mixture, that will increase the idle, then just trim it back down.

Did you go through the instructions as to setting the low end???.

It is in the manual under "Adjust the Carburator low-end for idle and transition"


If that is not in your manual you can get it from http://www.bmeengine.com/BMEdocs/BME_Instructions.pdf

All these engines work pretty much the same, it doesn't matter which brand.

The plug gap is not what will give you good transition, read the tuning section and you will get a better understanding.

Yes, thank you Jemo, it is exactly what I did, they said (manual) that it is good to lean as much as possible the low end and after, back it a bit, but I think It may need more or may need just more breaking in?? As I never have one before, I would like to know if I have to be patient and them the idle and reliability will come or if I am missing something that it is not on the manual. THANKS AGAIN

Redrata,

I think you may just need a little more run time on the engine. Even then, I don't think the idle rpm will get much lower, maybe down to 1600 rpm or so. Good luck!

You may have to wait a while, but you should not have to have dead stick landings, even when it is brand new.

ptgarcia is correct about the rpm.

Ok, I think I was expecting an idle about 1500 or less (acc to manual) but it must be for larger engines only. What it is important, is that the plane does not move while on ground. I will try today with a higher (2100) and richer idle. (I have been trying this before, I think I will do it again but more " aggressively") Thank you

My BME 50 was like that for a while but changed as it broke in. Sounds like you just need more time on it!

Edgeman,

I feel better now, the engine runs great, I like it a lot, but sometimes It presents this tendency to quit while idling. I will try it at higher rpms for a while and a bit richer. This info you (all) are sharing with me is very valuable and appreciated. Thank you.

The lowest available idle is also affected by the weight of the prop & spinner (acting as a flywheel).

One of mine will idle at 1800 with a light wood prop, but will idle at 1200 with a heavy composite prop.

Hi again,

I am using a very light prop and spinner, it must contribute to have that kind of unstable idle !
BTW: I need to reduce the noise of the engine, could anyone tell me if it is worth to buy the pitts style muffler. I have the bme stock muffler, but some people are complaining... If I order the pitts style, should it work better?, or at least, would it sounds any nicer?

My BME 44 settled down nicely after a couple of gallons. Oil mixture affects idle also. Run only 87 low grade gas with Lawnboy ashless oil mixed exactly to 40:1 and this will be the sweetest engine you will ever own. Just be patient! Paul

I am using 92 Oct, we have not lower gasoline in Denmark. I am mixing 50 : 1 acc. to the manual. should I go for 40 : 1 ?
The engine runs great sometimes, but after 3 take off/ landings, start running not so good. Need more adjustments, last time it was not running well at high speed. Plug gap? Leaned the H needle was not enough. Engine sounds erratic at high speed. Dont know how to sove it.

50:1 is good.
Your 92 Oct. is probably the same as our 87.
The pitts style muffler should be quieter than the stock one.

Are you sure the engine is not getting too hot. Whenever you are having doubts about mixture, always go richer at first, you can't hurt you engine that way.

Yes, good advice. I was trying to lean it...but may be better to richen it a bit more, and yes, it was quite hot. Thank you for your patience, you all have been new sometime back, it is clear that you are aware of that, and are willing to help. Thanks a lot!!.
Alex

Stick with 50:1! What prop are you using? Shoud be around a 20x8, Pro Zinger or similar.. I found that an 1/8th or a 1/16th of a turn made a big difference on mixture screws! Seems as though it takes 4 gals. or so till they settle in.

Maybe you should start over again with the factory settings because top end and low end sort of work together. I think its 1 1/4 turns out on low end and 1 1/2 turns out on high end. Set your peak rpm first with high end needle and work with the transition and idle with the low end needle. Make very little turns (1/16 - 1/8) at a time. Always have a fuel filter right before the carb! I think 50:1 should only be used after the engine has at least 15 gallons run thru it. Paul

5 gallons is considered normal breakin time.

I am using a Mejzlick 20*10 max rpms 7060 , but running at 6800- 6900.
The engine is better now, I reset everything and started again as recommended. I gets really hot on the ground after 25 min. of continuous adjustments and it starts to hesitate and run not so good. So I opened a bigger vent. hole in the cowl in order to get more air trough the engine fins, but I do assume that what the engine really needs is to fly, so it will get much more better ventilation up there. I have the feeling that when I fly, the engine is cooler, much cooler than when on the ground and it runs better. I think I am going to richen the H screw even a little more and let the L screw as it is now, kind of lean. I am not flying yet, but I will soon.

According to BME instructions, do not switch to synthetic or run a less oil content till after 15 gallons. I'm going to listen to them even if it takes three or more years to run that much thru it. P.

15 gallons is a lot of fuel for break in

Ok I do need help again.

I adjusted the engine, it ran good for the first two flights then after a while it started to run erratically after mid throttle. It started to malfunction at the top of rpms and then all the way down to mid range. It ran good until mid throttle is achieved, after mid throttle, it can not pick up rpms. No matter what I did to the H screw (richer- leaner), it is the same, does not matter. After a short break, the engine was marginally better, just to fall again under the same situation. So the heat is in the equation, but It did run good idle to mid throttle ?. The spark plug is OK, the ignition is working at least from idle to midrange, but I can not run it after that. Any ideas?
I adjusted the H screw reaching first a peak, then I back it a little, dropping some rpms (200).
The L screw is lean, but not so much.

This is copied directly from the BME Manual: Page #8

BREAK-IN OIL:
We recommend the use of a petroleum-based oil, such as Lawn Boy Ashless or Stihl Chainsaw oil for breaking-in all BME engines. Use the break-in oil until approximately 5 gallons of fuel has been run through the engine. ALWAYS MIX THE OIL ACCORDING TO THE MANUFACTURERS INSTRUCTIONS!
Using the break-in oil will help to ensure the proper seating of the rings to the cylinder walls. This is IMPORTANT if the full potential of the engine is to be realized.

Every other engine manufacturer calls for 5 gallons as break in time BME is no different.

If you think the needles are set and you have enough cooling. How is your ignition battery, you said this started after two flights, have you checked your battery at this time ??.

Has the ignition timing ever been changed from the factory setting ??.

Hi,
not the timming have never been modified (I dont kwon how to do it), but you may have a point.
The ignition battery is 2000 map, after flying it had 5.26 volts and I have been cycling it, so it must be in top condition. BUT the place where it is gets kind of hot (at one side of the firewall box) does it would affect the batt top performance?

I am going to place the ignition battery and kill switch in a cooler place to see what happens(behind the firewall box). It might be that the battery can not cope with the demand of the ignition when the place where it is now, gets hot. The engine has good cooling, but where the battery is, is very close/exposed to the engine. I have not so much place in there. You can see at my gallery, that is the plane...Also I might consider to place a Ni Cad ?, so it would deliver more map to the ignition in a shorter time. I have a Ni M. Sounds ok????