needle setting OS15FP max rc

getback Fri Jul 11, 2014 2:12 pm

I AM HAVEING A LITTLE TROUBLE GETTING THIS ENGINE TO START//Had it running once needle was about 4 rounds I think and throttled it back no idle or idle bar plug , then it just want come out of flood I guess ? I even used air to blow out the cly/ exhaust / carb. with the needle shut off , after it would pop but not start even if I shot some 30% nitro in it want hit. I am using 20% fuel an 0s plug I think and around 3 amps on my meter.....I got this at swap meet good comp. but did not tear it down as I don't have replacement gaskets and wanted to see if it would run without going into it Laughing

any suggestions ? Thanks Getback

pkrankow Fri Jul 11, 2014 3:07 pm

It is a .15, so 15% nitro is probably what it wants ("big" engines are 0% to 15% nitro typically) It should still run on the higher 20% nitro content. Added head gaskets might be needed though for best operation.

It is a RC engine of dubious storage so I would suspect plugging of passages in the air bleed portion of the carb. Soak the engine a couple days in denatured alcohol or fuel if tear down is not possible. Soaking the carb is recommended before attempting tear down, as it is often all that is needed. Don't mess with any screws, just the needle. Blow it out when done, flush the needle seat without needle.

The engine should idle at about 1/4 throw. Less than that should shut the engine off. The RC setup is usually neutral to about 1/2 "up" trim for idle, trim "down" for engine cut.

(The engine might be fine, just too far throttled back on the bench)

On the bench you need a "servo" either for manual or radio operation, or a wire with a friction stop on it for manual operation (trap the control rod wire in a clip or something). Engine vibration will move the throttle settings if they are not wired down. Of course using soft wire and wiring in wide open throttle (WOT) is an option too.

Phil

getback Fri Jul 11, 2014 8:42 pm

ok Phil Thanks , Ill take it off the bench and clean the carb , make sure the fuel feed holes are cleared and run it again ?? that's what I guess got me the first time I tried it cranked up ...............But What would you start with as a norm. start for the needle ? Thanks Eric

pkrankow Fri Jul 11, 2014 9:39 pm

If it started at 4 turns, WOT, then that seems reasonable as a starting point. Adjust to a nice "song" or steady peak tach at WOT, then go rich 1/8 turn or so for the first bench run. It "should" restart at that setting.

My fox 35 is some 7 turns out to start, blubbery rich, then 2 turns in for running (not really broke in yet) I started at one setting (prolly 3 turns) and ran on prime, adjusting by quarter turns till it stayed running off prime. This isn't the first engine I have done this with either.

The 15 FA owners manual is not listed on the OS website. The 15rx, a car engine with a similar carb, says 2 1/2 turns out. The LA use remote needles...

http://www.osengines.com/manuals/index.html

Phil

getback Tue Jul 22, 2014 7:35 am

well Phil , I ended up taking the carb off so I could ck. the o-ring , removed the needle , head , back plate. the piston did not get removed but it needed a cleaning , soaked it a day in alcohol , blew it all out good the back plate gasket tore so I sealed it with copper coat gasket compound . It did not have a head gasket Huh...

Anyway set needle on 3.5 turns primed it up good and vala--- got two good runs started like a champ found my tack second run 15.4 with 7x6 gray prop on 15% ...Then on what was going to be the last run after cooling off it would start but only very short run 10 seconds like it was running out of fuel but fuel was there , tried flushing and blowing needle assy. out ,but no better so I have got it back off the stand and will soak the carb. again. I have a question about the needle / venture set up sence it only goes 1/2 way into the thought does it feed through the end or have a bleed hole for the fuel ? hope you can understand what I am saying if not i'll snap a pic. Thanks as always Eric

GallopingGhostler Wed Jul 23, 2014 10:54 pm

getback wrote:well Phil , I ended up taking the carb off so I could ck. the o-ring , removed the needle , head , back plate. the piston did not get removed but it needed a cleaning , soaked it a day in alcohol , blew it all out good the back plate gasket tore so I sealed it with copper coat gasket compound . It did not have a head gasket Anyway set needle on 3.5 turns primed it up good and vala--- got two good runs started like a champ found my tack second run 15.4 with 7x6 gray prop on 15% ...Then on what was going to be the last run after cooling off it would start but only very short run 10 seconds like it was running out of fuel but fuel was there , tried flushing and blowing needle assy. out ,but no better so I have got it back off the stand and will soak the carb. again. I have a question about the needle / venture set up since it only goes 1/2 way into the thought does it feed through the end or have a bleed hole for the fuel ? hope you can understand what I am saying if not i'll snap a pic. Thanks as always Eric

Could be a glow plug going bad. It may glow red, but could be coating is going bad. I'd try a new plug to see that that corrects the problem. Tired w/ Coffee Read

Surfer_kris Sun Jul 27, 2014 6:45 am

getback wrote: I have a question about the needle / venture set up sence it only goes 1/2 way into the thought does it feed through the end or have a bleed hole for the fuel ?

The fuel comes out at the end, so put it in the center or a little further out for a small gain at high revs.

what fuel are you using?
To me it is important to have 20-25% all castor oil in the fuel for the old-school engines. This helps to maintain a good seal between piston and cylinder. The old-school engines should never be fully leaned out either.

It is hard to tell/hear from the movie but run it on the rich side and with lots of castor and it should be fine.

Surfer_kris Sun Jul 27, 2014 6:52 am

Just realized that it might be the FP model (there was never any FA model as far as I know)?
Then it is an ABN construction, you still need at least 20% all castor though as these are prone to loosing their nickel plating. Also, try using the muffler with baffle and tank pressure line, as originally designed.

GallopingGhostler Sun Jul 27, 2014 7:36 am

Just looking at the engine from your YouTube video, getback, it looks like it may be the old baffle piston OS Max 15R/C. Could you provide a few photos of the engine left and ride sides? Does it have an ABC type liner (aluminum piston in a chrome or nickel plated brass sleeve) or is it Mehanite iron piston with a steel sleeve? Is it a flat head piston or got a ridge tab on the top (baffle)?

The old school iron piston with steel sleeve engines required at least a half hour to hour of fuel through them, to break them in to the point where one could break them in further in flight. I'd also go to a larger diameter mild pitched prop to break them in, like an 8x4.

Your description almost reminds me of an old school engine that isn't quite broke in yet.

getback Sun Jul 27, 2014 2:25 pm

Ok Been tied up with some other things ...

.. the Fuel is 15% castor how much/?? the engine 1707 stamped in the rear

andit is a FP

the piston is alum. and flat on top....I am thinking of mixing some of my 30% sig fuel with this fuel + some castor to and giving it another shot when I get the time!!! The engine may not be broken in it has a lot of compression , I think it did have a liner in the cyl. for the piston wouldn't come out with out being . Thanks guys I will check back alitttle later, Getback

Surfer_kris Sun Jul 27, 2014 2:58 pm

That fuel is mainly meant for four-stroke engines?
It is a little low in terms of oil content (17% in total, and only 30% of that being castor).

You don't really need more than 10% nitro (especially without the head gasket) so you could easily add some castor oil to improve the oil content. I would suggest using full castor oil instead though, as these engines are prone to shedding their nickel layer from the cylinder walls...

Also check the brand of your glow plug, the long reach ones are too long, you need a medium reach one like the OS#8.

Do you have the muffler? I think you'll need it and its tank pressure feed to get the engine to run right. The bolt spacing is the same as most other .10-15 engines, so you shouldn't have any problems finding one if it is missing.

**RknRusty** Sun Jul 27, 2014 5:35 pm

The first couple of times I took the head off my Thunder Tiger 25, an OS knockoff and probably similar to your 15, I thought it didn't have a head gasket too, but it turned out to just be stuck in place and was the same color as the head.

pkrankow Sun Jul 27, 2014 9:28 pm

Get out a powerful magnet an see! A rare-earth magnet like what is found on a name tag will generally go through the case and stick if it is a iron/steel engine, and not stick if ABN (OS doesn't chrome, they use nickel, slightly less durable than chrome so piston and cylinder need replaced as a set.)

Phil

GallopingGhostler Sun Jul 27, 2014 10:05 pm

getback wrote:Ok Been tied up with some other things .... the Fuel is 15% castor how much/?? the engine 1707 stamped in the rear andit is a FP the piston is alum. and flat on top....I am thinking of mixing some of my 30% sig fuel with this fuel + some castor to and giving it another shot when I get the time!!! The engine may not be broken in it has a lot of compression , I think it did have a liner in the cyl. for the piston wouldn't come out with out being . Thanks guys I will check back a little later, Getback

Getback, your engine is an OS Max .15FP. It looks exactly like my FP. Instructions may be found at: http://www.dieselrc.com/download/osfpseries.pdf

Recommended is 10% nitro, but I've used 15% on mine without problems. OS recommended 20% Castor oil, but that was 25 years ago. I'd stick with the 20% oil due to its plain bearings, some synth doesn't hurt to keep down excessive Castor oil varnishing.

Anyway, the OS 15FP is a jewel of an engine, I really like it.

**Cribbs74** Sun Jul 27, 2014 10:17 pm

It really is a good running engine. Smooth as silk.

getback Mon Jul 28, 2014 1:42 pm

Phil , It is ABN no magnetism inside at piston . Kris I have the muffler for it but I could nt get it no the test stand ...I will look at that again, and see if I can come up with another prop,She was smooth as silk when it ran Ron, Thanks for the pdf info. file there GallopingGhostler ........ Does anyone here use OPS plugs I have a few RC 300 I blew one out in this engine tring to get it started , Don't know what plug is in it one that came with the engine , hopefully I will try to run it again this afternoon , Getback Very Happy

getback Mon Aug 04, 2014 10:06 am

Ok I did nothing to the engine but mount back on stand ( I think I may have overheated the engine before ) got her fired up and did several runs on the engine 1/2 throttle /wide open very rich/ idle and so on about 8 Oz or so of the same fuel . I carefully checked the head/cyl. for too much heat. The needle setting is yet to be desired ?At needle adjust it would not change rpm until 2-3 rounds were turned ? I am sure this engine just needs to be broken in alittle more and I believe it will be an easy starter and good runner It ran a bit better every time and starting was much easier as I get to know the engine.... now for a plane ! Thanks for all the advice once again. Very Happy

Getback

GallopingGhostler Mon Aug 04, 2014 11:37 am

If you're talking about the high speed needle and not the idle bleed screw, then you may have an air leak around the carburetor base. There should be an O-ring around the carburetor base that seales that joint. If you don't have one, an RTV sealant like Permatex Ultra Gray (used for transmission cases, etc.) will work.

And BTW, this engines does not require a lot of run time to break in. Being ABN, there's no need to run slobbering rich like the old Mehanite iron piston in a steel cylinder sleeve engines. After several runs, it's ready to be mounted in a plane and flown, to further the break in.

Surfer_kris Tue Aug 05, 2014 4:14 am

getback wrote:At needle adjust it would not change rpm until 2-3 rounds were turned ?

How many turns open do you have?

This is a typical scenario/reaction when there is not enough fuel draw from the carb itself. Opening the needle doesn't help, because there is simply not enough fuel draw to pull more fuel. So you do need the muffler pressure for a correct fuel delivery, only then will the main needle be the limiting factor.

getback Tue Aug 05, 2014 7:27 am

There is a O-Ring under the carb. it is alittle flat but has some pressure when installing carb. and I did not have one to replace that would fit.//// Kris I would say 4-6 turns out without it killing the engine from getting to much fuel /// I am going to make a test stand that I can use the muffler / pressure and rerun the engine .. can you tell me the correct size I.D. fuel hose I should be using also ? Please, the hose I am using is tight to fit I am guessing 1/8 ? and I'll get it set up since I don't have a plane to mount on yet and go from there . I have read over the instruction s and don't understand what the air bleed sc. is for ? Thanks Eric Very Happy

pkrankow Tue Aug 05, 2014 7:56 am

"Medium" silicone fuel line

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD728&P=ML
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK129&P=7

3/32 ID

If the o-ring under the carb is intact, undamaged, and supple/soft then it should be OK. There is a tendency to get a nick or split in the o-ring, which is all it takes to cause an air leak.

Phil

GallopingGhostler Tue Aug 05, 2014 8:02 am

getback wrote:There is a O-Ring under the carb. it is alittle flat but has some pressure when installing carb. and I did not have one to replace that would fit.//// Kris I would say 4-6 turns out without it killing the engine from getting to much fuel /// I am going to make a test stand that I can use the muffler / pressure and rerun the engine .. can you tell me the correct size I.D. fuel hose I should be using also ? Please, the hose I am using is tight to fit I am guessing 1/8 ? and I'll get it set up since I don't have a plane to mount on yet and go from there . I have read over the instruction s and don't understand what the air bleed sc. is for ? Thanks Eric

Tank placement is important. You have a very large tank that has considerable vertical displacement. It appears to be lower than the engine. A two to 4 ounce tank has a narrower range. I'd get the tank level when full to be in line with the needle valve.

Fuel line size is okay. It would be better to use a smaller tank and get it closer to the engine. I'd shoot for a couple inches max.

Air bleed adjusts the idle fuel mixture. All it is a screw that tweaks the amount of additional air coming through the bleed hole to get a smooth idle. They describe a procedure to adjust. I've used a screw driver to adjust it live, but a caveat is although more precise, it is very dangerous to do so, hence their procedure. General rule of thumb for a starting point is closing the hole one half with the screw.

Additional comment, 8/5/2014, 7:18 MDT: Here are photos of my test setup with a Testor McCoy .40 Black Head Series 21 engine. Tank is 1 ounce.

needle setting OS15FP max rc McCoy40-BHw-YSMuffler

needle setting OS15FP max rc McCoy40-BHw-YSMuffler

needle setting OS15FP max rc McCoy40-BHw-YSMufflerBack

pkrankow Tue Aug 05, 2014 11:01 am

Air bleed is for idle speed adjustment. At this point keep the throttle more than 1/2 open and don't worry about it.

Once the engine is set for high speed try throttling down, it should shut off at the bottom of the range, but it should run and idle till you get there.

Phil

GallopingGhostler Tue Aug 05, 2014 4:34 pm

pkrankow wrote:Air bleed is for idle speed adjustment. At this point keep the throttle more than 1/2 open and don't worry about it. Once the engine is set for high speed try throttling down, it should shut off at the bottom of the range, but it should run and idle till you get there. Phil

I think this is what you are trying to say, Phil. If not, then let me clarify: There are two screws. The air bleed adjust the idle fuel air mixture. Usually, you adjust this until you have maximum idle speed at the lowest desired idle speed, which means the idle air fuel mixture is optimal. Then there is the idle speed screw. Normally it adjusts the minimum throttle position or speed at idle. Most set the idle speed screw so that the throttle is completely closed. Then adjust the throttle cable, so engine is at the proper idle speed with transmitter trim tab to upper position and thottle stick in minimum position. To turn engine off, transmitter trim tab is moved from maximum (up) to minimum (down) position, which closes the caburetor venturi completely.

pkrankow Tue Aug 05, 2014 5:06 pm

GallopingGhoster, Thank you.

I have never actually needed to adjust an airbleed, or the low speed needle on a properly functioning carb. Since I didn't need to mess, I took the advice to leave it alone too. OS uses screwdriver heads for air bleed and low speed, meaning they expect most people to just leave it alone!

Phil

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cleaned and running , But?

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