Lancair-RCU

Im posting this here as most of the OS140 users will be in this forum.
I have a brand new engine, which starts very easily, started first flick the first time I tried. I let it run at about 1/4 throttle for about 1.5/2 min the first time and shut it down. Now Im ready to go fly, I want to make sure I can get full throttle and an idle before flying.
This afternoon a mate and I tried unsuccesfully many times to get to full throttle. It starts very easily using the reverse flick method. At about half throttle maybe a tad more it dies. We tried, with the coarse taper needle set from 1 1/4 turns open to 2.5 turns open and each time the same result. We tried the finer taper needle at 1.5 to 2.5 turns open and same result. We then found some tiny pieces of plastic in the fuel filter, removed them and same result. Removed the fuel filter completely and same result. Tried lengthening the pipe set-up, same result.

My guess is its dieing because its too rich, some splatter of fuel from the carby when it runs and a fair bit of oil from the pipe outlet. I was reluctant to go leaner settings on the needle as I dont want to cook it being brand new. Having said that, there were some small bubbles evident in the line between the pump and carby (but no more than I see every time I fly my OS50SX) so maybe it is dieing lean. When it dies it does sag in RPM before it dies which makes me think rich rather than lean and the splatter from the carb makes me think rich.
This is my first OS140, but between my mate and I, we've succesfully ran engines from 46's through to Moki 180's and four strokes as well and never had so much touble getting full throttle out of an engine before.
Right now Im feeling like a dumb newbie who shouldnt be playing with big boys toys

Any ideas people ?

David Gibbs

Sounds very abnormal for a 140 -- not something I have seen so no definitive answers.

Sounds possible that the low/medium jet is fine (rich at low revs as they tend to come), but leaning out at high revs. One area I have sometimes had problems is with blockages in the carby jet. Blow the needle valve both ways just to make sure if you haven't already. Pull the carby barrel out (remove throttle stop and pull sideways), pull out the jet and blow all that out to. I can't imagine it is the pipe causing that kind of problem (unless you are using something very obscure).

Do others know how to check the pump?

bla bla

PM me your private email address and I'll send you back an article published by Jim Oddin/RCM from an gentleman down under that was having great sucess changing the pump pressure on the RX.
Don't know if'll help your exact problem, but it certainly stopped the buckets of fuel being spat out of the carb at midrange setting on my RX.

Eric.Henderson

Could any of the debris in the fuel line have made it to the pump?

The pump is not that hard to dissassemble and check for crud.

Regards,

Eric.

rodney tanner

Normally the 140 RX pump does not need any ajustment. So I would leave it be for the moment. After you have checked for crud in the places mentioned above, I would try the following:

Make sure you have an OS F plug fitted.
Make sure the low end screw has not been moved and is in the middle, verticle setting.
Try pinching the fuel pipe as you go to wide open and it starts to falter and then close the needle to give constant full revs, then back off 3 clicks.
Sometimes my 140RXs don´t like to transition to full revs straight away on the first start of the day so I end up just pitching the fuel line a tad and then they are fine for the rest of the day.
Take it easy for the first five flights and then set the low end screw lean about an 1/8, as per the manual and set the pipe length, as required. If its the OS Hatori check the manual. I use a Macs header and an ES Pipe that works great right out of the box :-)

Good luck, and keep posting here until you have it right.

ini

Make sure you have healthy fuel with 10 to 15 % nitro. OS 140 RX does not run full throttle with FAI ( 0%) fuel, maybe it will idle.

ini

Chris Moon

My Feedback: (8)

The 140RX likes to have the idle fairly lean in order to transition well. Also, do not try and run it slobbery rich, as the pump will just flood out the motor. You will not burn it up by getting it to run a little leaner, in fact it is probably the only way to get it to run at full throttle. The pump is very strong as set by the factory, but I would not mess with it.

Lancair-RCU

Thanks for the replies guys.
I'll have another go this afternoon after checking for debris in the needle/carby.
I have an OS F plug in it.
Im using the supplied OS/Hatori pipe and the fuel I was using came from another mate who Id just seen use the same fuel running his OS140, if I recall he said it was %15 nitro 20% coolpower. Ill be mixing my own today and make it 15% nitro, 18% coolpower.

ab1

THE 0S 140 IS A FANTASTIC MOTOR. I OWN 2 OF THEM AND THEIR GREAT. I HAVE HOWEVER, COME ACROSS 2 NEW MOTORS THAT DO EXACTLY THAT. IDLE FANTASTIC YET LOAD UP IN THE MID RANGE TO THE POINT WHERE THEY STOP. I THINK YOU'LL FIND IT IS A FAULTY PUMP THAT SHOULD BE RETURNED TO THE DEALER. EASY FIX.. PULL THE BACKPLATE/PUMP OF ANOTHER 140 AND TRY THAT. THE FAULTY PUMPS WERE ON MOTOR'S PURCHASED WITHIN THE LAST 12 MONTHS.

Lancair-RCU

Well, today I shortened the pipe setting to about 240mm effective header length and started with the fine taper needle at 1.5 turns and success. Managed to run a full tank going from rich four stroking to fast two stroking and back every few seconds. The idle was fast and I couldnt go lower on travel settings so stopped it to reset the throttle for a low idle. Refilled and had a b of a time getting it going again, eventually ran out of time, so will now wait until I get to the field and have plenty of time to play and actually fly it.

Lancair-RCU

Just thought Id post here the final results and what worked.
First off, Im running the OS supplied header and pipe (the Hatori #900 2C140 pipe) and was using a 16x12 APC prop.
Today I cut 8mm from the header pipe to get a shorter effective header length and changed to a 17x12APC prop.
Runs fantastically, 7800rpm flat out and an idle of just over 2000rpm (a tad fast I know but until its broken in properly it'll do) I can let it idle for 30 or more secs and go to full throttle with no hestitation or rough running, I can slam the throttle open or closed and no problems.
Seems the pipe was too long for the prop I had and not enough load on it with the smaller prop for it to get on the pipe properly. After flying it I may find I need to shorten the pipe some more to adjust for the unloading of the prop in flight.
The info to get it going came from another local guy who's had exactly the problems I was having.

Lancair-RCU

Well after having it run at home perfectly, I took it to the field this morning for the first flight. Whilst doing and engine running range check it loaded up and died. After several more attempts at getting it to idle or at least hold mid range RPM without loading up I gave up on flying it. I dont want to risk a dead stick on the first flight.
Ive read NOT to touch the low end until it has quite a few flights, but suspect I may need to lean it out some. Today was hotter and more humid (around 70% today) than it was when I had it running well, but not a lot hotter. About 29C (84F) today and 27 when I had it going good.

Rodney, did you mean 1/8 of a turn lean in your post above ?

Right now its near 30+ C, so Ill wait unitl it cools off this afternoon and have a play.

MHester

My Feedback: (1)

yes 1/8 turn lean it needs from factory setting.

I run a different exhaust, OS/hatori and ES pipe. I have never had any trouble whatsoever with this combo, and I also run at least 16x13 to 17x12 prop.

if you run within these parameters and still have trouble, then you may have a rare "bad" OS 140RX.

One note. The factory low end setting is rich, so if it's loading up, then you need to lean it out. This engine likes to be a little lean on the bottom end. Try this: Crank it and run it up to full power. Let it heat up to operating temp, and then drop it to idle. let it idle for about 30 seconds. Then run it up. if it does ok, then you're good to go.

If not: Do the above and drop the engien to idle. Now let it settle for about 15 seconds. With a pair of hemostats or pliers, pich off the fuel line to the carb. The engine should increase SLIGHTLY in RPM and then die. if it dies suddenly, it's lean. if it jumps up really high in RPM, it's rich. Adjust from there.

Try that and see how it goes.

-Mike

klhoard

My Feedback: (10)

OK, this is going to sound really, really strange. . . but here I go. . .

Have you checked the rear bearings?

My OS 1.40 would load up excessively 3 out of 4 times on the ground so bad that fuel would run out of the carb. I tried everything until it finally deadsticked one flight. The rear bearings were rusted to the point they were making noise. I replaced them and it runs like a top ever since.

Don't ask me to explain what the rear bearings have to do with the mixture. . . . I don't know. . .it is just one of those mysteries of life. . .

MHester

My Feedback: (1)

Yep there's that too. How long since you ran it the first time as opposed to how many flights since an overhaul?

if the bearings are bad, the engine is shot. keith is 100% dead on target. So take that in to acct too.

-Mike

Lancair-RCU

Thanks for the replies.
The engine has never left the ground under its own power, so far it has about a total of 2 x 16oz tanks of fuel through it, over 5 or 6 running times. Once only a full tank when I was getting the tuned pipe settings right. It was first started 2 weeks ago. I have read so many conflicting reports re the rear bearings, some have hundreds of flights and they're still good, others just a few flights. Ill look into getting a new bearing on monday. Apparently, from talking to other Aussies about it, a well stocked bearing supplies outlet should have stainless steel sealed bearings the correct size. Hopefully if we dont get a thunderstorm this afternoon /early evening Ill give it another go trying to lean out the low end.

BTW Im running 10% nitro, 15% coolpower homebrew fuel.

steveg_oz

G'day Andrew,

Sorry to hear you're having problems. I was hoping you'd be sorted, so you could sort out mine!! Cyclone is covered, wing bags made (thanks, mum) and first colour coat went on the fuz today. Amazing amount of work just to cover and finish a 2m model. So I hope to start installing gear on Oz day. Dallas is saying that he shortened his header by 15mm.

Did you install a shim?
Are you running low nitro?

That's will help me decide how much to hack off my header. If you went 8mm, I'll try starting with 5mm off.

See you at the field.

Regards,

sTeve

Lancair-RCU

Steve,
I was hoping yours would be finished by now !!

Whats with buying the Excelleron 90 ? To preserve your 2M plane. I wasnt aware they were like good wine and got better with age or I'd have bought Dallas's.

No head shim at this stage. 10% Nitro in an effort to keep costs down and 15% oil, I worried it might be too little oil but there's still heaps being spat out the exhaust and lots of smoke so . . .
Yeah I cut 8mm off, now down to 237mm effective header pipe length.

It "should" fly tomorrow morning at Ballina field, trying for an 8.30am takeoff or thereabouts, its great having no time limits on our flying in Ballina, Ive been airborne as early as 7.15am.

klhoard

My Feedback: (10)

That is exactly where I get my new bearings. I just took the old one into the bearing supply store and threw it on the counter. In less than a minute the guy walked back out with the exact bearing. The didn't have the stainless bearings in stock, but ordered them for me within a week. (About $10 cheaper than Boca)

You can stick your ear down by the spinner (Glow plug disconnected!!) and slowly rotate the prop between compression. If you can hear anything, the bearings are going. You are correct - some guys bearings last hundreds of flights, while others last just a few.

The common thread seems to be heat. Make sure the rear of your engine gets PLENTY of cooling air. I've seen some guys go so far as to create an air scoop surrounding the whole spinner. The hotter that the rear bearing gets, the quicker it rusts.

If you need to know how to change the rear bearings, PM me and I'll let you know how I do it in about 20 minutes.

David Gibbs

FWIW I also have found heat the killer on the main bearing -- hence scoops to ensure it gets continuous air flow over it. For replacements we use NTN 6000 LLU for front and NTN 6904 LLU for main -- both are sealed and available from local bearing suppliers (down here in OZ anyway).

As for changing header pipe lengths -- I am really surprised. I have two in service for the past 4 years, with standard header and pipe, and never had a problem. These things are pretty damn robust. I have flown with stuffed bearings, pipes that have slipped within joiners (neither deliberately!) and even though it has had a minor impact on peak RPM -- nothing that makes them unfliable in the ways discussed here. And there there are at least a dozen other OS 140's in our Club alone with similar history.

While I may have been lucky, when I have had problems like the ones described here it has always been fuel side and my problem, either dirt somewhere it shouldn't be, or a blockage or a leak in the fuel system (one way valves, fuel tube nicked somehow during building/repair). 15% nitro, 20% oil, and an additional shim in the head (unless it is one of the newer ones) seems to be a bullet proof recipe.

This is is no way meant to suggest you may not have other problems -- just to suggest that changing header pipe lengths etc. as part of the standard approach to setting them up sounds a little extreme. They just aren't (usually) that fussy.

Lancair-RCU

Well, it flies.
I leaned the low end 1/8 of a turn and it ran much better, though still loaded up if let sit at slightly lower than mid range for too long, as I found out on the second flight. Luckily our field has lots of over run room, not runway smooth, but smooth enough for emergency landings.
After the first flight, whilst the engine was still hot I noticed some noise in the bearings so will replace them tomorrow. So if someone could post their method of bearing change it would be much appreciated.

rodney tanner

Try a tad leaner - in increments of under an 1/8, just nudge under the width of your screw diver. I can´t believe that the bearing is shot after just a few tanks! Unless it had been lying around the shop for a long time before you bought it and moisture and rust got in there. That has been known to happen.
Keep at it! The OS 140 is a great pattern engine. Both mine have the Mintor 3M 140 twin head, which really helps the mid range transition and lowers the compression slightly, giving a wider sweet spot.

klhoard

My Feedback: (10)

Gather these items:
1) Thick leather gloves
2) Aluminum cookie sheet
3) Hot oven - 350F (Not Celsius!!)

Here's the process:
1) Turn on oven to 350 F
2) Disassemble your engine down to just the crankcase, front and rear bearings, and crankshaft. (Don't lose the little key on the front of the crankshaft!!)
3) Tap on the front of the crankshaft with a block of wood and it will pop out of the back.
4) Put the new rear bearing onto the crankshaft and place this assembly in the freezer
5) Put the crankcase on the cookie sheet, rear of the engine pointing down, then place the cookie sheet in the oven.
6) Listen carefully to the oven, and in about 10-15 minutes you should hear the rear bearing fall out of the engine and hit the cookie sheet.
7) Put on your leather gloves, and grab the freezing cold crankshaft and rear bearing from the freezer.
8) Pick up the engine from the oven, turn it over, and slide the crankshaft w/bearing right into the crankcase.
9) Let the whole thing cool, then re-assemble.

I Hope this helps!!!

Eric.Henderson

One additional tip. To get the con-rod off the shaft you first need to slide the conrod all the way to the back on the wrist-pin. Quite often the wrist pin gets a bit "cruddy". The trick is to clean the wrist pin with a loop of dental floss to allow the conrod to slide more easily.

If you ever take the the con-rod out of the piston you can tell which way it goes back by the chamfer in the p/bronze bushing. The chamfer goes nearest the crankshaft.

Eric.

David Gibbs

A couple of other tips.

I have always taken the liner out first (I am not sure of you can do it without doing this - never tried) -- and is usually easier with a little heat on the cylinder (heat gun etc.).

When you put it back together remember that there is a key in the piston where the join in the piston ring needs to go to stop the piston ring rotating. Given the number of inlets/outlets on the 140 it is not a good idea to have the ring able to rotate and get caught . . .