Mr Cox

Usually there is nothing there, it is not needed as the conrod cannot go anywhere...

the Wasp

My Feedback: (1)

no O-rings !!, but there is a Brass or Bronzes Bushing inside both ends of the Connecting Rod (see photo below), if there is no Bushing in your Rod you need to buy a new Rod, and you should buy a new Wrest Pin too,,

also note in my photo, you will see the Bevel on the large Bushing, that Bevel must butt up against the Flat side of the Crank Shaft (a must),

also note that once the small end of the Rod is installed into the Piston there should be a little back and forth side-play in the Rod.



Jim

Hobbsy

My Feedback: (102)

Do you mean, in here?

andernamen

My Feedback: (3)

Okay, I guess there was nothing there. After pulling the piston out of the anti-freeze, the conrod was stuck and wouldn't move at all. I didn't want to force it and break something. I heated it with a torch and disassembled it. Not sure what would have caused the conrod to freeze up while being heated in anti-freeze???? Anyway, the brass bushings are still there and everything otherwise appears okay. I will put it back together and see what happens. Thanks for all the replies.

the Wasp

My Feedback: (1)

well most likely it was frozen up before you hot tanked it,, but if it was Castor that froze up people say soaking it in fuel should free it up

Jim

dmrcflyr2

My Feedback: (43)

A recent purchase for a VERY good price. Can you say well under $300..... I did a complete disassembly, clean, bearing replacement. This is how it runs right now.

Hobbsy

My Feedback: (102)

That is schweet, well done.

blw

My Feedback: (3)

The antifreeze should have made everything free up. Glow fuel is probably the best thing for dissolving old fuel deposits.

hsukaria

Some questions I have that may have been discussed in the past but not sure where to look. I have 3 OS engines I purchased well used and plan on rebuilding/restoring them. I will replace the bearings, that's not an issue. The question is the compression/pinch.

OS 25FX - Will the Magnum 25 XLS piston/liner set fit on the OS 25 FX? I know that for the 46 size it works out fine.
OS 32SX - Any ABC (chrome) p/l sets out there that fit? I heard that there is a guy who replates OS engine liners with chrome, but I don't have his contact info. Anybody know?
OS 35AX - I would also like to have its liner chrome plated if somebody would do that.

I know that the chrome plating may not be cheap, but the 25FX, 32SX and 35AX are worthy engines. Thanks.
Edit: The reason I want to re-plate is because these engines are well worn and barely have any pinch left, if any at all.

hsukaria

My present OS engines list:
OS 15 LA silver
OS 15 LA blue - BNIB
OS 25 FX - needs rebuild
OS 32 SX - needs rebuild
OS 35 AX - needs rebuild
OS 46 SF ringed
OS 61 FX
OS 70 Surpass II

aspeed

I am pretty sure the XLS would not fit, as it is the newer version. The previous one could maybe. It would be the XL or ASP A or 1 model. Just engines in England would maybe have parts or know about it maybe. I have a .32 SX with a peeled liner and bad bearing too. Hmmm I would be willing to bet the liner chrome plating would cost more than the motors are worth. Some of the dune buggy guys make up a ring to clamp over the sleeve and squeeze the liner a bit to give a bit of compression. I would just run them as is and see how bad they really are, as long as they have not peeled.

hsukaria

I also read somewhere that some guys tap the bottom side of the piston with a metal rod to spread out the piston a bit. Desperate measures I suppose. Maybe I'll use a ton of castor oil and see if that helps.
Peeled liner!!! Never heard of that happening before!!

aspeed

I pick up a couple LA .40s a couple months ago. One was peeled and the backplate fell to pieces. Oh well, another $10 i'll never see again. Extra castor is good. Foxes thrive on it. They wear out pretty fast but keep going for a really long time anyway because of the castor or whatever oil you choose. As long as it is 25 30%.

hsukaria

Yeah, that plastic backplate/needle valve assembly on the OS 15LA has me worried. At least the piston/liner set and the plastic backplate for the OS 15LA is reasonably priced, unlike the others. I will try to make time to bench run the 3 old engines to see if they can be used as is.

aspeed

I just had my first flight of the year Wednesday with my LA .15. Great fun, got the adrenaline going at full throttle. My LA .40 will live again even with the small crater that peeled off. I will make a backplate/motor mount on the lathe and tie wrap the plastic needle valve remnants onto something. If it destroys itself, it will be fun anyway..

hsukaria

Just now first flight?

How will the 40 run with the peeled liner? My 55AX wouldn't run more than a few seconds after it peeled. As soon as it warms up, all compression is lost and quits.

I just don't like the remote needle valve mounting on the backplate, and that goes for all engines, not just the LA series. I prefer the angled back needles like the AX series, Thunder Tigers, and Norvels.

I checked out the 3 engines last night and they don't look so bad. I hope to bench run them today to get a better ideal.

aspeed

Yep, just now. It has been a bit windy lately like usual, and the nice days have been used building a triple garage. It is pretty much done now, roofing done, just need a door, caulking and hydro now. Not such a big rush for a while. There is just a little flea size piece of nickle gone. I mostly got them for control line stunt practise, so they may not last long. I like the rear mount needle, but it often is in the way and hits the back of the motor mount, and they still break off.

hsukaria

Ok, bench ran the 3 OS engines that I acquired used recently. I used 18% nitro and synthetic/castor oil blend (not sure of exact contents). Used APC props, stock muffler, and the same glowplug for all three.

25FX - 9x6 prop: 13,800 rpm
32SX - 9x6 prop: 15,800 rpm
- 9x7 prop: 14,800 rpm
-10x6 prop: 13,400 rpm
35AX-10x6 prop: 13,300 rpm

I'm digging that 32SX!!
All three engines had great throttle response. But a couple of questions:
1. The 25FX had black/grey goo oozing out of the front bearing. Is that because it sat so long without running or does it mean the bearings need replacement?
2. The 35AX had been in a greusome crash from the previous owner and required crankshaft replacment. He replaced the crank but not the bearings. Should they be replaced as a precaution?
Thanks for the help.

aspeed

We use an 8-6 on our .25s so they rev around 16,000 rpm where they are happiest. The .32 should be revving around that speed too. The old loop scavenged motors could take a bigger prop load. If the bearings are not biinding at all, or there is not a lot of end play, I would just use them as is. The crash likely bent the crank tip and needed replacing, I doubt the bearings had too much damage. If they run smooth and the cages are still on. The goo coming out the front is good, it is getting lube. It being black maybe not. Could be just running a bit hot from big props, or prop drive washer rubbing or whatever. Others may have different views. I seldom/never replace bearings, where others replace them twice a year just in case.

hsukaria

I have not sensed any binding or end play in these engines. So I will re-consider replacing the bearings.
My plans for these engines (if I get 'round to it):
-OS 25FX in a Screamin' Demon delta wing. Will use a APC 8x6 as aspeed recommended, maybe a mousse can muffler too.
-OS 32SX in a Sig Kobra without landing gear to keep it light and fast.
-OS 35AX in a World Engines Hawk 460 with foam core wings and fiberglass fuse. No landing gear either.

Jesse Open

I sold my original 120II in May for $175 . Wish I had known you were looking. It had a ton of hours since 1979 but ran great.

Hobbsy

My Feedback: (102)

Should I paint the muffler blue too?


I took 3 pictures of the idle over a couple of minutes, it never wavered.


Max rpm as steady as the idle
I am setting up second LT 25 that was a gift several years ago from cousin who was moving to Fla. He had an LA .25 on so I continued the theme. I have two LA .25's now. I ran mine which has more time on it than his.

LA .25 blue
Prop===Graupner 8 x 6 three blade
Plug===OS A-3
Fuel===Wildcat 10% full synthetic
After a good 20 minute warm up aro purge
Max rpm=11,580
Best idle==2,080 smooth easy purr no burblling.
Very quick on acceleration.

EyeflyRC

My Feedback: (147)

If you cannot find the original retention screw, consider making your own. Buy a screw with the same thread and diameter at the hardware store and use a hand file to reduce 3/16" of the end of the screw to a smooth part like a tooth pick. This is the part of the screw that rides in the groove of the rotating barrel in the carb. I have done this on the carbs some old OS engines and it works fine.

Fast Pilot

I'm running the OS 200 with pump engine. This engine vibrates a lot. Is it only because it is new or it will always behave like this?
Please answer with honesty, not to console me. Is it a very bad engine?
Thanks so much

Hobbsy

My Feedback: (102)

Hopefully you are propping it below 8,000 rpm. The most thrust was generated by the 18x8. PROPWOT RPMIDLE RPMTop Flite Power Point 16X88,6202160
Top Flite Power Point 18X8---7620----2160 idle
Top Flite Power Point 18X10 6,890---2040
Top Flite Power Point 18X12---6270---2040
Top Flite Power Point 20X6-10---5660--2010
Top Flite Power Point 20X8---6300---1920

PS, there is a chart for the pumped version that supercedes that one, it starts at 16x12 and ends at 20x8.