alaflyer

My Feedback: (14)

I recently aquired used OS SF61 ABC with the PD-02 pump and the Type 86 carb. The engine starts and runs good. It will turn a 11-7 1/2 RevUp at 12,500 and a 12-10 APC at 10,400 on the stock mufler. I am having difficulty getting a reliable idle. The engine surges and eventually dies if I try to idle below 5,000 rpms. I have all the original manuals and have tried to adjust the Mixture Control Screw (very slight amounts at a time), but with no success.

All the fuel lines are hooked up correctly and there does not appear to be any leaks. The needle valve tunes normally at the top end, but it just won't idle. Any suggestions? I want to use this engine with a tuned pipe in a 70's pattern plane I am restoring (Phoenix 6), but I need to get a reliable idle before I start tuning the pipe.

Atlanta 60

My Feedback: (18)

I'd suggest replacing the all the carburetor o-rings...I'll try and get you the breakdown which will also have the o-ring part #'s you need...They are available from Tower...It's not hard to do and the o-rings get brittle over time...

Atlanta 60

My Feedback: (18)

OK..Here is a PDF copy of the OS Type 86 carb manual (see attachment)...

Order yourself a pack each of these part numbers (click on the number to go to the webpage)
[link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=27881800&search=Go]27881800[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=27881810&search=Go]27881810[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=27881820&search=Go]27881820[/link]
[link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=29015019&search=Go]29015019[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=24981837]24981837[/link]

Optional but I'd probably recommend a needle assembly also:
[link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=27681900&search=Go]27681970[/link]

********** Also..Don't forget...No Petroleum based products around your SF-P as it will damage those silicone o-rings!! ***********

Have Fun...

Chuck

alaflyer

My Feedback: (14)

Thanks, I'll get those ordered.

dhal22

Good timing, as I need to start an SF of mine and get it running.

Atlanta 60

My Feedback: (18)

So Sorry...I forgot to include the needle valve o-ring (24981837)...I added it to the list above...It wouldn't really be necessary if you ordered the complete needle valve assembly but if your like me you'll want to have spares laying around anyhow... [8D]

JRgraham

My Feedback: (1)

What kind of fuel are you running through that thing?

alaflyer

My Feedback: (14)

I am running Cool Power 15% with a #8 glo plug. No extra oil in the fuel.

JRgraham

My Feedback: (1)

Hmm, yeah that fuel should be just fine, if its a correct mix (there is a rare case of incorrect mixture's from factory).

Id try another batch of fuel, similar to that mix just to verify its not the Fuel..
Also, try a plug with an idle bar on it. I dont think the OS #8 has one.

We use to run these motors for years, but its been a long while now. Being your running a stock muffler, that should be Okay.. but Iwouldnt rule out the muffler causing conflict either, at idle speeds. Although thats a long shot too, like bad fuel.

At least that would help rule out a couple things, before you go tearing it down to replace o-rings and gaskets.

Another note on these engines, they are HARDon bearings.. We use to have to replace the main bearings sometimes once a month, front bearings would be replaced about every other time, or so. The ABC piston and sleeve make a higher compression, and pound on bearings. Even loading after run only delay's the replacements.

alaflyer

My Feedback: (14)

OK, here is where we are: Fuel seems to be OK since it was the same container I have been using with other engines without problems, however I switched to a new gallon I had - no improvement. The #8 plug is a "short" plug with no idle bar. I do not have any short plugs that have idle bars. The #8 is what the manual recommends, but I did try a new A3. The A3 is the same length as the #8, but with a different heat range. Anyway, that did not help.

I have the engine on my test stand with an APC 12-10 prop. The engine starts very easily and responds well to needle valve adjustments at WOT, but refuses to run below about 6,000 rpms. I am turning about 10,200 with that prop. I did notice that around 6,000 air bubbles appear in the line from the pump to the carb. At higher rpms there are no bubbles. There are no bubbles in the line from the tank to the pump at all.

I had one of these engines several years ago in the Phoenix 6 that I am restoring, I just don't remember having any problems with it. Of course this is a used engine and my memory is not what it used to be! Who knows what "adjustments" have been made to this particular engine over the years. I hope no one has played with the pump adjustments, but I have no way of knowing. Unfortunately, spare parts for these old engines are not easy to find, especially when it comes to carb, pump or piston/liner sets.

I would really like to get this engine running for "old time sake".

I ordered the O-rings and we'll see if that helps.

JRgraham

My Feedback: (1)

Have you tried running the motor a little bit with the glow driver still connected and powering the glow plug? This sometimes makes the difference, and can narrow down problems. If it runs smoothly with the driver still connected and 'ON' the plug isnt glowing correctly.. Im assuming you have tried this..

One other thought, if your running smooth at high RPM's but struggles and dies at the low end, being it has sat for years, there could just be some crud in the pump from sitting, that just wont 'clear out' when running. High RPM's there is enough fuel being pumped/forced to pass, but low end is trickle fuel, not able to pass easy to the needle valve...

I'd carefully tear down the pump and clean it out with some fresh fuel, since you are planning on rebuilding it anyways with new O-rings soon.

Also, might be worth inspecting any gaskets in line with the fuel system.. back plate, etc. We are talking about the pump thats mounted to the backplate of the motor, right?Not the Perry style ossolating pumps.. If its a perry.. bypass that thing for a bit, and run the motor off the muffler's presure for a test.

Also.. seriously inspect your fuel lines for any pinhole's ornicks. easy to not notice them, and can get nick'd easy when installing the tank. they can be damn near invisible.

Atlanta 60

My Feedback: (18)

I'd personally advise against taking the PA-102 pump apart this early in the program...There would probably be no benefit from disassembling it except for cleaning and your flushing it just by running it...There are no replacement parts and no replacement PA-102 pumps if it gets messed up...It's not that complicated to take apart if you're very careful but a little tricky to get back together...Not worth the risk if the pump is working...There are other things to do first...(My Opinion)

I'm not saying don't ever take the pump apart, just right not now...I'd go through the engine thoroughly first and disassemble the pump as a last resort...I don't mean to sound like an expert as I've only taken one apart myself (for curiosity's sake...he he), it worked afterwards so it can be done...

I've purchased quite a few of these engines (the RF-P version) over the last 5 years or so most of them used...My standard procedure is each one gets taken apart, inspected, carb re-built and new bearings and gasket before running...I have yet to have a bad pump with any of my RF-P or RF-P Hanno engines so far...

It bugs me that you say there are bubbles in the pump/carb line at the lower rpm's...I don't ever remember noticing that with any of my engines...Something doesn't seem right that's for sure...

There should be "tamper proof" paint on the pump screws...If it's broken the screws have moved...

I'm using OS#8 or K&B 1L plugs here...


****Another note****

There are two different rear bearing sizes used on the SF & RF engines over the years...It's handy to know which one you have before ordering new bearings (Trust Me...he he)

The earlier engines have a 30mm rear bearing...They are suppose to be a little tougher on rear bearings but still excellent engines!!

The later generation SF & RF engines have a 35mm rear bearing which is the same size as the Hanno...

As I understand it; Back in the day OS was having some complaints from the pattern community about the rear bearing holding up on the SF/RF engines ...When they designed the engine for Hanno Prettner they put a Super Nice 35mm Stainless Steel bearing in the "Hanno Special" engine...Apparently they also started making all the standard SF/RF engines with a 35mm rear bearing (not stainless though)...

**photo courtesy of raindave**

8178

My Feedback: (17)

The carb supply line should not have bubbles but they are OK in the return lines. Are you sure you have all the lines connected to the correct fittings?

tony0707

HI
I have endless experience running the OS 61 sf engine with no pump on 15 % morgan omega fuel
my first thought is the diaphragm in the pump has dried up and gone bad as they will over time-,try to get a stock , no pump back plate if you can-,no parts are available for the pump if you need a pump you can run an external perry pump off the stock back plate with a pressure fitting
the bearings in these engines will last for many years using the fuel i suggested if you run the engine correctly-not lean ! the engine is extremely user friendly
the air in the fuel line appears to be from the pump so my recommendation above
be very sure that all gasket surfaces are clean an no air is getting into the crankcase anywhere
the engine will run hot if air is getting in
do not attempt to adjust the needle valves when the engine is hot it must cool completely down before each run then start tune over
i run a 12/6 or a 13/6 apc on my engines i have three and been running a 61 SF for 20 years that i s when they first came out
if you run a glo engine lean on a full syn fuel you will fry the engine -, castor oil breaks down over 100 degrees higher then of that of a syn fuel and bond to the metal parts at this time just when you need the protection
running a glo engine lean at some time is a given although never intended it happens to the best of us and must be identified as quickly as is possible and corrected
just my two cents
BEST REGARDS TONY

tony0707

HI
all due respect -, you bearing wear is very extreme you should not be going through bearings that quickly i have bearings in one for 18 years flying it a good deal over the years do not use cool power they need some castor oil in the fuel-when i used cool power ( cruel power ) the first few years of flying i to had bearing problems all bearing issues went away with MORGAN OMEGA FUEL i have not replaced any bearings in my 25 different glo engines for many many yearsi fly a lot
BEST REGARDS TONY

tony0707

rccrasher65

My Feedback: (35)

Sorry to say but, but someone did mess with the pump adjustments, I would go and change all of the Orings as suggested but I had one doing the same thing and a nice motor mechanic told me how to readjust the pump, even though your not supposed to touch the factory settings. It's been so long ago and have since sold the engine but, I hate to say your problem is with the pump, it needs reajusted to get the correct idle. George

JRgraham

My Feedback: (1)

Yeah, it was extreme Ithink too. I'm sure some was how we ran the engines, but O.S. replacement bearings were just fair quality too. There use to be a nice aftermarket replacement for those motors back in the 90's that would last longer, and was real smooth.

Also we ran tuned pipes almost always on them.

There is also a difference not mentioned yet here with this motor group/erra, some had ABC piston/sleeves, where others had the standard nickle whatever. Though not anything related to a fuel issue..

Ican tell you though, we were not the only people that 'were hard on' bearings.


Yeah, id try running it with a stock backplate too, with muffler pressure. cant hurt while your waiting for parts.

TestPilot-101

My Feedback: (4)

I had similar problem with my OS .60 w/pump. To really find out if it's a pump problem, try this first. Clean out the carb. ( Keep your fuel line attached to the pump and take the output line and have it discharge in to another fuel tank so you can observe the fuel output). Then using a separate tank, hook it directly to the carb with your fuel line.Fill both tanks with fresh fuel. ( Set your tank level or above the carb, with or without  muffler preasure.) And adjust the carb as if it were a non-pump engine. While the engine is running now you can observe the fuel flow at all speeds. If it runs ok, the problem could be between fuel tank to the pump.

Twinhydro

My Feedback: (6)

Lose the pump and make sure you have LARGEtubing from tank to carb . Richen the low end mix and let it idle for 5 mins and then check the transitions through the throttle range and adjust accordingly. Happy Trails !

Atlanta 60

My Feedback: (18)

I've attached a couple more manuals which you may or may not have...Just in case someone can use them here ya go...

crankpin

My Feedback: (15)

Thanks !
Crank

alaflyer

My Feedback: (14)

I really appreciate all the advice and suggestions. The "O" rings are on order. The "How to Adjust the Carb" info is especially good. More info there than is in the regualar manuals. I tried a new tank and lines and bypassed the pump as per Test Pilot 101. I could get it to idle a little better, but not as good as it should. With the "In" line hooked to a separate tank and the "Out" line that normally runs to the carb into a separate container, the pump will drain that separate tank faster than i can fill it! If that is any indication the pump is probably OK.

When I get the Tower order I will repace O rings and clean the Carb. I am determined to get this thing running right. When I do I post what I found. Thanks again.

crankpin

My Feedback: (15)

Not an expert here, and usually rely on other's with experience. I had been using Omega 15% in my 61SF's. I use ProPattern 20% in the YS110 & 115. I decided to try the 20% in the SF's, to just keep one type of fuel for both.

First time the 20% in the 61SF's, excellent run all around. I did not tach it, but can only say, pulling down to idle, and transition, best yet with the 20%, IMO, better then 15%.

Crank

Atlanta 60

My Feedback: (18)

Now with the same arrengement above:
empty the "out" line so there is no fuel in it...Then turn the prop over by hand one compression stroke at a time...You should see the fuel move in the tube **approxamatley** 1/4" per stroke...

Note: it may take a couple of strokes for the pump to prime it's self and get rid of any air ect....After the 4th or 5th compression stroke it should be pretty consistant in "moving" the fuel...

Have Fun...

Chuck