Love my bme 50, but the idle is rough, and somewhat inconsistent. Manual says I should get a steady 1000-1500 rpm. I can get a steady 2000, or shaky 1500 (cuts out with prolonged idle). I cant imagine 1000rpm.

Motor has 1 gallon through it. Leaning out the bottom end helps, and its out only 1 turn now. If I lean it out further, I cant hand start the motor. It just starts, runs for a second, and dies... Idle is slightly rough, but not bad...prop is wood 22/8.

Will it just take more time?? Input???

Open the low end back up about a half turn and idle it about 2k then run a few few gallons through before you try tweeking it any.

Those figures may come true AFTER break in.

how many gallons do you believe break in may require??? My weedwacker trimmer idled well after one tank...I guess Im impatient

5 gallons

No matter what you do with a BME, you're gonna end up with some pretty bad shake...that's the way they are designed. There is alot of metal that is ground off in a BME that is needed in other engines...things like counterweight, bearing spacing (there is none), amoung others that by design make them shake. Some (very little) of the vvvvibes will go away with tuning, but even the best (if you can call them that) will still shake a plane apart in short order. Just a word to the wise...

flyin_hot

You have no idea what you are talking about and reading your post suggest that you dont know anything about the engine.



Keith
BME

OK Mr. BME,
We'll take this once cause of shake at a time...Care to list your bearing spacing for your BME 50? Care to exapand on what you know about dampening? Oh wait! there is no dampening...that's why this guy is having so much trouble to begin with...I know I know...the lightest weight is everything...gotta have some sales pitch...right? Airplanes need to stay together though...

I have a BME 50 on a Great planes extra (PW). It's fairly new and doesn't have 5 gallons through it yet.

I don't think mine shakes any more than my good and heavy 3W.
I don't have a concern that my airframe is going to be destroyed, the engine runs great.

There is a post on RCU about a DA 50 shaking badly, what is the bearing spacing on it,???

bpu699, Don,t worry about the shakes until the motor is broke in, all single cyl. engines are going to shake a little. We have to remember we are putting 50cc of engine on 13 to 16lb air frames and at idle there is not enough weight and mass to hold these little hot rods still. If you mnt. one of these in a 30lb+ war bird you be here praising how smooth your BME is. BME is a fine engine and if you take your time breaking it in and adjusting it you will be rewarded with and strong long lasting engine. Adjusting gas motors for optimum running is a long process and should be done slowly until you learn the motor, I have several brands and they all have there on personality as far as the carburetor adjustments, set it to the factory settings for a few gallons and then start the adjustment process 1/16 turn at a time. The low speed adjustment will be a compromise between smooth idle and good running and starting habits. To lean gives very nice idle but may be difficult to start cold and maybe a engine stall at the worst of moments. Most problems I have had in the past seem to all ways be related to lean low speed adjustments.

Good Luck and be patient.

I don't know what bearing spacing can possibly have to do with vibration..Fore and aft spacing or up and down spacing ? Care to enlighten us ? The outside diameter of the crank bearings is such that the bearings are held tightly in the case..They don't move..The crank may or may not be able to move sideways in the bearings, but that movement has no effect on vibration..No engine is made with loose bearings..Only US engines have roller bearings on the crank, and they are just slightly loose up and down....
I have not seen very many BME engines, but the ones I have seen have no grinding on the counterweights..Balance on a single cylinder engine is a compromise, and some are better than others..The vibration of an engine is determined by the percentage of the piston, rod, pin, bearing, and clips that is counterbalanced by the crank webs, somewhere around 80%....It will not change after the engine is run..A heavy engine will soak up more of the vibration than a light one..
It's impossible to balance a single cylinder engine, unless someone has found a way to change the laws of physics....

Go Keith! I have your BME 50 and its a great engine! I couldn't imagine, having a more user freindly engine, it has run great from the start! I would buy another BME in a heartbeat for my next plane.

Keith, I think there are so many people that will stand by your engines that you should just ignore the fools who don't know what they are talking about. You have been great to work with.

I have been such a fan of BME engines and KEITH since the very first 44 that I bought.......In fact, I am such a fan that I have TWO (2) 55 Xtremes on order........Yea maybe they are late getting out, butI KNOW IT WILL BE WORTH IT.

flyin_hot


I dont mean to personaly attack you but when you talk about bearing spacing, counterweights ect. You are stating things that dont matter or are absolutely not true. I will answer any questions you may have to the best of my ability. As for the BME 50 it has two bearings for and aft the two counterweights just as any zenoah engine is built. We have sold thousands of these engines without any problems other than some ignition sensors quiting. We have never ground the crankshaft or counterweights to reduce weight. We have many of these engines at our local field mostly on hanger9 caps. All are overpowered, run exceptionaly smooth and are hard mounted. As for dampening what would you like to know about the Stewart Warner machine we use for ballancing or our ballance factor number? Its always the guy on the outside looking in that knows more than the manufacturer.


Keith
BME

Im sure the motor will be great once its broken in . In fact, at high throttle, the motor is very smooth and vibration free. I bought this motor mostly based on its excellent reputation, and Im sure that I wont be disappointed... I guess I have to get those 5 gallons through it...

I have to jump in here and maybe I'm out of place but, I really enjoy the amount of information and technical knowledge that comes from the members here at RCU. Why is it that right in the middle of a good thread does someone have to jump in and rip it apart? I have seen a member posting in this thread flame everything except a DA engine (from other threads). I know everyone has opinions, but is this really an opinion? I'll keep reading the good stuff and ignoring people like this. Thanks to all who keep the "GOOD" info coming! Welcome aboard Keith, I'm sure your knowledge will be a great asset to RCU.

I have never owned a BME, but he is right about single engines, It is physically impossible to perfectly balance them. You can help some with counter weights on the crankshaft, but that is only a bandaid. The engine wouldn't last very long. Size and weight of the engine and airplane, motorcycle, lawnmower, etc only seem to muffle some of the vibration that they all have.

mine vibrates quite a bit @ idle too...but - ive only got 2-3 tanks of gas thru it so far (nothing really)...but above idle shes as smooth as silk...

im just working out a severe rf problem with my setup...

everyone says PCM...PCM...but - this weekend i met a guy @ the field who has a 35% staudacher with an FM HITEC reciever - NO NOISE TRAPS...and better still - NO PROBLEMS!!

so - ive got some work to do - but THE ENGINE IS SOLID...a breeze to start and THANKS KEITH for the easy linkage setup...

my dad just got a 3w24 for his supercub...and hes not a happy camper...the carb is in the back...and the carb/choke linkage is a little screwy...very messy.

so THANKS again KEITH!!!
(oh - and i sent my ignition back to the guys @ C&H...they took great care of me and turned it around in 24 hours...VERY COOL!!)

Keith are you going to be at Toledo this year? If so I am looking forward to meeting you, and chatting about engines.

What is the horsepower rating of the BME 50 and 55?

I haven't been able to locate information on the net about these engines.