factory

The brochure, outline drawings & parts diagram (Model A) for these early engines has now been scanned & added to the manuals thread. That strange piston with three rings is mentioned in both the brochure & shown in the parts diagram/list. David

They remind of the rubber belts used in tape players, but they would probably instantly turn to mush when exposed to gas/oil mix (the ones used in Philips products turned to sticky mush with age, gas/petrol is one thing that could remove the sticky mess left ). I'm sure there must be suitable gas resistant seals like that available. By the way I've been busy tonight converting 360MB of scans of the first O&R Compact Engine literature from August 1960 to a 5MB pdf, which is now available to download from the manuals thread (as it was all together I have left it together). I may add the brochure on it's own to the appropriate section as well. David

The cylinder/exhaust collector gaskets are only found as new-old-stock, I have been making my own using modern gasket sheet and a set of punches.The O-ring cylinder seal can be replaced with a modern one. The end float on the crankshaft is fairly normal for these engines. I've still got to locate a coil, the spares engine the starter came from is missing this and a few other bits. Thanks for the picture showing the serial number, I can confirm the A-139-2 is the correct starter dog, this type was first used with the A-47-10 flywheel after serial number 015997 and for all later flywheels (except for the much later Series 13B & 20A engines). Which points parts do you need? I'm assuming something broke as they normally just need cleaning & the gap re-setting. There is one part no-one has mentioned that I cannot see on your engine (it's also missing from my Chug-A-Saw engine), that is the governor vane, do you need one of those? David

That's a shame about the coil as they rarely fail, I've had the wire break inside the insulation before. For reference, I checked the older style coil on my Chug-A-Saw, it measures approx 2.4kΩ, from memory the later style coils (made by Phelon) measure much higher at around 6kΩ. Here are some pictures of the vertical gas/fuel tank used on the Chug-A-Saw, it is the same size as the oil tank. I was going to suggest making a tank using coffee tins, but they are slightly bigger in diameter and won't fit the space available. David

Could you spare one of each of those? They would be very useful in finding the nearest equivalent in the UK, I have quite a few of the first 6000 engines here, including one that's been in bits for years as they were missing. David.

Not yet, it isn't actually dated but came with a letter dated August 1960, it's going to need adding, but it won't be tonight, it's very late here and I just stuffed up a post I was going to add in another thread. Also I have noticed a problem/error with the 1961 parts diagram, it shows #5-2 & #33-2 pointing at the wrong items (they are swapped). Reading the descriptions below the diagram gives the correct names, the manual that came with the C/Saw has a correct version of the diagram. David

The 1962 price list states items marked with ⃰ must be used on engines with serial number 006072 or under and on (early) engines without a serial number. It also states items marked with a double ⃰ (sorry MS character map lacks correct symbol) must be used on engines with serial number 013072 or under and on (early) engines without a serial number. The exhaust collector gasket (arrowed in your picture) is #5-2 on the parts list, the manual states to "lubricate this gasket generously" to prevent it getting damaged when screwing the cylinder down. I suspect this is a thin section O-ring or square section ring that is slightly larger is diameter than the cylinder O-ring, I can't confirm which unless someone finds some NOS (I would be interested in some if they turn up too). It also confirms two packing band gaskets, part #5-9 are used for both the cylinder seal & feather valve seal. Note: the reed/feather valve assembly changes after serial number 006073 as do a lot of the gaskets & seals. David Edit: added picture from August 1960 parts diagram, which also shows the three piston rings found in CNew's early engine.

There is no exhaust collector spacer used on this engine, the exhaust collector is wider than the newer ones. @Wallfish I will double check the manual with parts lists that came with the C/Saw I bought, it covers 1961/62 and early engines with no serial numbers. David

Is the serial number below #006072? It certainly looks like an early engine, there are two gaskets for the cylinder, one at the top of the exhaust collector part no. #5-2 (I think this maybe a rubber seal but can't confirm), the other below the exhaust collector is part #5-9 this is a rubber seal (exactly the same as the one for the feather valve). David.

Not a silly question at all, many years ago I bought a NOS industrial punch kit (as shown below at the current price) for about a third of the normal price on ePay from a seller that clears stock from closed down companies; Things to note about the above kit, the punches are all metric, it also includes the arm with cutter for other sizes. The filters can be cut in one go, as some of the punches can be used together, this depends how close the two sizes are. David

Thanks @Fishnuts2 that's why I mentioned it, as no one else had complained or mentioned problems with synthetic oil, the only other oil I tried (many years ago) was some crap sold by petrol stations & was intended for mopeds, it was horribly smoky compared with the Stihl oil (it never got near any O&R's). I've just been reading the comments on a Norton motorbike forum, they also have problems with fuel lines getting dissolved by modern fuels, which can be a fire risk if it leaks all over a hot engine. David

Yes that is similar to what I found when I searched for Alkylate pre-mix, the Stihl one also uses synthetic oil (the Ultra one), we had one member complain that their O&R overheated with the synthetic version, it would be interesting to hear if anyone else has had problems using it or not. I've been using the red Stihl HP (mineral version) in my vintage 2-stroke engines, which was recommended to me by someone who uses chainsaws for a living and has a collection of vintage ones too. I'm definitely going to look for a can of the non-mixed Alkylate fuel (advertised for 4-stroke engines) and mix it using the Stihl HP mineral oil at 32:1 for my O&R engines. Most petrol stations in the UK have the pumps marked as having up to 5% ethanol (E5), but this will be increasing to 10% (E10). David

They can really ruin your day if they get sucked in, here are pictures I took a while ago to show how bad they are even if they look in one piece. They usually don't survive long enough for my to get the camera out. Before After There are two pieces of foam to clean out of the double air cleaner, I find one piece of new pre-filter is usually enough in both types (this may vary depending on type of foam you use). David P.S. I find similar disintegrating old foam in the vintage electronics I repair, I had to replace some yesterday in a HP voltmeter from the 1970's (used to either keep circuit boards in place, or prevent vibration being transferred to certain parts, such as some vacuum tubes).

I meant to add these last night but got distracted. Here are parts which look to be for holding the trimmer head on, I'm missing the shaft that goes between the 201254 shaft part and the PTO shaft on the engine. Part 400642 is a cap that fits on the end of this second shaft which has internal spring clips. And here are the parts that make up the air cleaner assembly, the first two parts 87-4 & 122-1 were previously used as exhaust parts, part 200946 is a modified version of the standard air cleaner part without the raised edge (see comparison with standard part) and the last part is a typical fixing rod for the air cleaner assembly (minus nuts & washers). And the last part is the complete trigger cable assembly part 400611, I've no idea if there are different lengths of this for the various models of string trimmers they made, I put the loose parts on the end of the cable, they look to be fitted & soldered during assembly. David P.S. there are a few more small parts, a bronze bearing, various spacers & fixings that I haven't pictured yet, not even sure if they are for these.

Here is another early one that doesn't appear to be painted (not mine). I never took any pictures of mine, it arrived after the recent bereavement, I only had a quick look & pulled out the paperwork. The other Comet tool I bought over winter went very badly, I got scammed, it never arrived and I lost the money as I didn't claim it in time. David

Here is what I said around 12 months ago when someone asked about the value of a Tiny Tiger, along with certain chainsaws they are very common, remember to check recent sold prices/completed listings, but be very careful with "buy-it-now" items as ePay hide the actual lower sold price if "best offer" was used. I'm not sure a refurbished one would sell for more than a nice clean original one, it all depends on the amount of people interested at the time of selling and what they are prepared to pay. David

I should be able to help, is the coil open circuit or just need the perished rubber wires sleeving? I'm fairly certain the vertical fuel tank has the same dimensions as the horizontal versions (oil tank on this tool). The cylinder gaskets will probably leak if re-used, if you need to replace the shafts seals the only option is to use O-rings of the appropriate size. If you strip the engine down it's a good idea to use a large tray to catch any bearing rollers that may escape. Have you done anything with the gearbox, they originally used oil which either dried out or leaked out, they eventually changed to using grease. David

Just a note, the alloy handle used on these (can't see it in the picture) is a weak point , the thin section where it attaches didn't survive shipping on mine. David

I'm not sure about that Alkylate premix stuff, there isn't enough oil in it for my liking, also it uses synthetic oil. But they do have ethanol free fuel on it's own, which I could mix with the Stihl mineral oil at 32:1. David

Welcome Ray, @CNew has new laser cut carb diaphragms, if you haven't already seen it check out the carb rebuild thread at the top of the O&R section. David

It's all pure speculation unless you have pictures showing both the engine type & the model number (61MX3 ?) on the pump and several examples turn up to prove it's not been re-painted. The three rather low-res pictures could be from many years ago, worthlesspoint harvests information from ePay listings, but usually only a couple of the pictures. The muffler certainly doesn't look correct for military use. As for the drone mention that is complete nonsense, people got confused with the large 4 cylinder McCulloch engine re-used in the early Bensen B-8M Gyrocopter (which can have an O&R engine used for the pre-rotator mechanism only). McCulloch made the drone engines. David

That's OK, if you do have any questions about the Tiny Tiger or these engines we will try & help. David

OK thanks for that picture, that is a Motorola 1N3491R diode rated at a maximum of 50 volts at 25 amps (date code week 49 of 1973), the 'R' in the part number indicates the polarity being anode to the case. This seems to have suitable ratings for the Tiny Tiger charger circuit and is the correct polarity. Note: This component is now obsolete, any for sale will either be new-old-stock or relabelled parts. Question is why they are with the Tiny Tigers, could it be possible they were returns that never got repaired? The manual does mention that they can get damaged if the battery is connected the wrong way round. David

@RobertDFW I'm a bit confused as to why you've quoted that post twice but haven't added a comment or question about it. David

The older engines used a ball bearing for the valve under the diaphragm arm, this would often get gummed up with stale gas/oil mix, they even recommend replacing the ball bearing instead of trying to clean it, but at least you can still get ball bearings as they are a standard part. The redesign uses the rubber seal on the diaphragm arm, these seem worse than the ball bearing as they no longer seal due to gas/oil mix and/or ageing badly. Unfortunately the seal was sold with the carb repair kits, same as the brass valve only being available in a new carb diaphragm bowl assembly, I can't help thinking one reason they did this was to generate more parts sales. The diaphragm arms with rubber seal are very difficult to find now, if it's bad you could replace the carb parts with the older versions (i.e. the carb bowl bottom half, a ball bearing & the older diaphragm arm). David P.S. Avoid using any gas that contains ethanol for the fuel mix for these engines, look for ethanol free (non-oxygenated) gas instead, it may be harder to find, but it should cause less problems with stale gas, swelling of rubber seals and corrosion from it attaching moisture.