hi

this is my quote from an os forum

'MY os 140 quits(hunts and quits) at 1/4 throttle in flight it seems that the engine has fuel starvation at this piont,because when I prime the engine it take a couple of flicks to prime it .I did test the engine on ground (pointing the model vertical at full throttle and back to idle then full throttle . idle reliability-left the engine running at idle for one min and to full throttle (didn’t miss a beat)).My set up apc 17x10N home brew fuel semsynt 18%oil 15% nitro glow type F os carbon pipe. I have also read that after 30 flights the engine needs to be cleaned. Can I inject methanol in to the pump by a hand pump with out removing the engine and pipe but leaving the pipe attached to the main needle (also removed) and disconnect the 2nd pipe ?'

Well I did clean the pump and found a lot of gum,althoug I think it did help becasue the flight duration was longer but still the engine is hunting even when my funtana 140 is flying stright and level at 1/4 thottelThe engine quits at TDC.Should i install a hopper tank ?I did flly with the glow on.Should i adjust the slow end needle ?


Alan

Alan, are you sure that you don't have a bad throttle servo (hunting)?

You should not leave your onboard ignition on when the engine is running peaked out. It is hard on the glow plug and it doesn't do the engine any favors.

Why are you accumulating goo in the carb at thirty flights? I'd investigate that issue (dirty fuel) before I changed anything on the engine. The OS 1.40RX is intended to be used at a competition engine. I can't imagine any pattern flyer putting up with an engine that needed to be disassembled every thirty flights. Many pros put more flights than that on their model in a week. That would consume a lot of their time. I suspect there were certain qualifications to that 30 flight period that we have missed.

Good luck. You have a great engine.


Ed Cregger

Ed

on the manual says that one has to clean the pump after 30 flights.Gum is normal on glow engines beacuse the menthnol avporats leaving the oil.i will check the servo aswell.Does it have anything to do if the pipe lenght is not right?
Alan

Ed

on the manual says that one has to clean the pump after 30 flights.Gum is normal on glow engines beacuse the methanol evaporates leaving oil with turns in to crystals(the engine is filltered which i cleanned) .i will check the servo aswell.Does it have anything to do if the pipe lenght is not right?
Alan

...

have you tried running on store bought fuel

Do not remove the pump!!!!!!!!!!!!! while it looks easy with four bolts the backing plate is the back of the pump. if you remove it you may never get it back together again. 160.00 mistake that may well be.

Yes you can inject straight methonal into the pump at the inlet i use a regular syringe like for filling up a control line plane. i just go slow with it. I have run these engines for over a thousand flights. the only time i ever flush the pump is at the end of the year. I run a sullivan crap trap filter from the tank to the pump. and of course a filter in my fuel can.

I do not run onboard glow and the engine is mounted inverted also. I normally use powermaster 15/16 mixed 50/50 with powermaster 15% mean and green. I have also used coolpower 25%. S&W 22.5% Wildcat 15%Helimix and Wildcat 15% all with straight synthetics. My favorite fuel for it is 15/16 which is a 15% nitro with 16% synthetic. just can't get it anymore. I do not take the carb apart to clean it when i flush the pump it goes out the carb.

Also at the end of the day i do not run my engine dry i just drain the fuel. and put the plane away.
The most important thing to remember about the 140RX is the rear bearing. usually the stock bearing will go bad in about four gallons of fuel or 40 flights that will most definately affect the midrange and idle qualities. I replace my stock rear bearing using the OS140CFI bearing as soon as i get the engine i do not use the stock bearing.
I use a OS header on one engine with a ES carbon pipe
A mac header on one engine with a carbon pipe
a OS header with the stock OS aluminum pipe on the other engine.

And yes it will matter on the pipe length but probably not with your symptoms I leave the header at the stock length and start by putting the pipe about 3/8" 10mm or so away and then flying it. then i will try pulling the pipe farther away from the header. till it gets to peaky where it jumps on the pipe. then i start bring it back in.

The motor is a excellent engine. Except for the stock rear bearing. Which as i said in a previous post i use the OS140CFI bearing. Also a 3M mintor dual plug cylinder head will fit on the engine. I have used them before with excellent success also using a OSF plug with a K&B1L plug also. Not sure if you can get K&B plugs but the 1L plug is a excellent plug for this engine also.

what about the hopper tank?

I think it is unusual to use a hopper tank with a pumped engine like yours. Are you trying to cure some problem like fuel foaming?

What kind of oil are you mixing to make your fuel? I like castor in fuel, but if it is getting sticky, you might need some pure synthetic oiled fuel(after run fuel?) to run through before you put it up at the end of the day; that and run the engine dry. The 30 run clean up sounds like lawyer talk for i dont want to fix it.

I've never used a hopper tank with my 140RX's. Don't think it is necessay. If you bought this engine new it should come with two needle valves. one the tip is kind of stubby, the other one is the narrow one that is the same as the 61FX that is the needle valve i run. It makes the needle a little less sensitive.

d bodary, it sounds like you have a good bit of experience with the 140 rx. i plan on buying this engine for a pattern plane i'm building now. feel free to keep posting your knowledge here. thx.