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  • Gender Male
  • Location Cheshire UK
  • Interests Stationary engines and vintage electronics
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  1. Octura and du-bro nitro fuel

    Very few O&R's that have been used for RC models seem to have been converted for glow, the adaptor/bushing for using 1/4" glow plugs in the 10mm or 14mm cylinders aren't very easy to find, seems people either have to machine one to fit or find somewhere selling them. I did however find one place that has some ready made adaptors/bushings that may or may not be suitable; http://www.thunderboltrc.com/index.php?main_page=index&cPath=100_183 As these Helicopters aren't exactly common (working ones even less common) it may be a good idea to contact the owner of this one on youtube for advise, reading the comments it seems they aren't a big fan of O&R engines though. There is also an RC airplane that someone on youtube has built using an O&R chainsaw engine, it runs with the original carb & magneto ignition too. I do have a couple of O&R's with different carbs that were used in model boats, maybe I should add some pictures if anyone is interested, one is a K&B and the other maybe a Waltron, both are standard spark ignition & air-cooled. There was also a heavily modified O&R with an Irvine carb sold recently on ePay. I now have (thanks to Webhead) a Tillotson HU carb that O&R/AEP used on a weed wacker, I plan to adapt one of my spare engines to fit this carb and will update the thread here with my progress; David
  2. I've done some resistance measurements of the stator windings of two 110V Tiger Tigers & the 230V Tiny Tor I have. The readings confirm the high/low voltage windings are connected together & everything is centre-tapped from the + output terminal. For the 110V Tiger Tigers the total resistance of all the windings (measured across the 110V outlet) was approx 5.7ohms, measuring from each side of the 110V outlet to the + terminal gave readings of approx 2.7ohms for each half. For the 230V Tiny Tor the total resistance of all the windings was approx 28.5ohms and the measurement for each half wasn't the same (14.7 & 15.2ohms), I don't have another to check the readings against as I had problems with the 230V output being low last time I tried it. I suspect it has a bad connection somewhere. I opened the Tiny Tor to measure the low voltage windings as the diodes prevent measurement from the outside, readings for each half were approx 0.3ohms after deducting the test lead resistance. All the measurements were taken using the lowest resistance range on a quality US made multimeter, which I check against a lab-grade decade resistor box periodically. I used to have a cheap chinese multimeter which was totally useless for low resistance measurements, you got different readings every time using the lowest ranges as the switch contacts are very poor quality. Better readings for the low voltage windings could be obtained using a low-ohmmeter as the measurements are at the bottom end of the lowest resistance range on the multimeter. I do have a nice vintage one but it's currently on the round-tuit pile as it doesn't work. Here is a DaveCAD diagram for the internal wiring of the 110V Tiny Tiger; There isn't much space for the wiring inside, I soldered the wires to the diodes on the Tiger I repaired as I didn't think there was enough room for connector blocks. David
  3. Yes if wiring was reversed, the exposed battery charging terminals would have 110V across them, the diodes are probably only rated for low voltage (so could end up short circuited). David
  4. The wiring for the AC 110V outlet has plastic insulation (probably supplied with the bought in 110V outlet) which rarely goes bad in vintage electrical/electronics, rubber insulation on the other hand always seems to eventually turn to either dust or a gooey mess as you've found. We even had a modern rubber cable fail on a 2007ish Weller soldering iron at work, the inner cores crumbled to dust causing a short circuit & blew the fuse. The two items in the casing with solid non-insulated wire leads are push fit diodes for rectifying the AC voltage to DC for the low voltage battery charging output. These will be connected to the thicker windings of the stator to provide the higher current required for charging. The ground lead is the wire on it's own on the other side of the stator. The AC 110V outlet will be connected to the thinner windings of the stator, be careful not to snap these, you may want to re-secure the cables into the windings with lacing cord as they were before. Thinner cable from a scrap mains lead would have been fine for connecting up these, as the maximum current drawn will be much lower. As for the the thin wires connected to the thicker winding, I've suspected they were as I got strange resistance readings when measuring mine. I will post a diagram of how I think it's all connected up when I've done some more measurements on mine as I didn't make any notes at the time. David
  5. Octura and du-bro nitro fuel

    Not sure I can help much as I don't have any O&R's with either of those carbs, a few years ago I nearly got a glow converted engine with the Octura carb, but the seller messed me about (and presumably several others as their ebay account soon got terminated). I've only seen two O&R boat engines with the Octura carb so they must be quite rare. Likewise the O&R with the Du-Bro carb is just as rare. Presumably a similar mixing ratio for glow fuel would be required, what do the modern glow engines of similar size use? Just be aware of early O&R compact engines with the plastic bearing housings as they could potentially react badly with some fuels/oils. The only O&R's that I aware of having problems with glow conversion & nitro fuel were the much older & smaller Ohlsson model engines that were commonly used in model planes, broken con-rods & cylinder head failure being two problems with these engines. David
  6. The generator stator windings do look more of a mess than usual, the rubber insulation of the wires always seems to disintegrate when disturbed, did the wires snap from corrosion too? If you can identify the high & low voltage windings, it should be possible to connect up new wires, if you can find some good condition wiring to connect up to of course. Be careful to not damage the insulation on the stator windings. You will probably need to clean the wire ends of corrosion for easier soldering, I recommend using a lead alloy based flux cored solder (not that modern unleaded solder rubbish, which requires more heat & has known reliability problems, it corrodes very easily too). Tin the ends of the wires with solder before joining together and sleeve any joints with heat-shrink tubing to prevent shorts. Here are some pictures from the restoration of my Tiny Tiger, it required the crumbling rubber wiring repairing, I took lots of pictures before disconnecting the wires and used different colour heat-shrink sleeving for identifying the low & high voltage windings. David
  7. There are two windings in the magneto coil, a low resistance primary winding with a low amount of turns of thick wire and a higher resistance secondary winding with many turns of very fine wire. The two wires connected together are one end of each winding, these are grounded via the metal core of the coil, as they are not insulated they may still be connected together inside. The thin insulated wire is other end of the primary winding and goes to the insulated bolt for the contact breaker compartment, the stop switch & capacitor wire are also connected here. The high voltage end of the secondary goes to the spark-plug, the insulation of this wire looks damaged (heat-shrink sleeving can be used to repair this) and the plug cap is also missing. I would check the resistance of both the primary & secondary windings if you have a multimeter and post the results here. Not sure how easy it would be the open the casing around the two ground wires, you don't want to damage the insulated wire if you try or break the very fine secondary wire. I used to open and repair small potted transformers (which were unavailable/obsolete) at work, the plastic casing could be broken off around the faulty area, gentle use of a small electric heat-gun to soften the potting compound, which could then be scrapped out in small bits to reveal the connections for re-soldering, araldite was used to replace the potting compound to complete the repair. I don't have most of the equipment to do this type of repair at home. The number 151 stamped on to one of the crankcase flanges is the engine type, it represents the engine specification & options, I have a Tiny Tor (same as Tiny Tiger) that also has a type B151 engine. The letters were used on early engines, B is a tank mount engine. There were letters or numbers used for many standard engine types with different options of tanks, various gearboxes, clutch and mounting types. Diagrams & parts lists for the standard types are usually in the master service manual, many manufacturers of tools & equipment with these engines would have ordered a custom specification engine. David
  8. I've also got some parts on the way, it's taken about 4 days to get from the US to the ParcelFarce depot in Stoke which seems quick, it will probably them another two weeks to move the parcel the last few miles knowing my bad luck with them . From experience it can take an extra week or two for international shipping between Black Friday and the new year. David
  9. I don't know what sort of Mylar was used, but they are usually re-usable, I found a good used one yesterday, also Wallfish had some new ones made as I mentioned before. Here are two pictures of the earlier rubber type check valve, I think it's obvious why I now consider this type a "replace on sight" part, sometimes the valve flap is missing or detached. I've been cutting my own gaskets, but do have some originals, I also bought new O-ring seals for the cylinder in the nearest available metric size, took me two attempts to buy O-rings of the right thickness. See this thread for more on that; I would be surprised if Webhead doesn't have new old stock exhaust gaskets too. David
  10. Yes the check valve is the transparent blue plastic sheet gasket shown on top of the diaphragm in the picture (they were fitted to my Tiny Tiger 400), the originals are usually clear (early ones are made from the same black rubber as the diaphragm), some have probably fallen out un-noticed when previous owners have tried to get them working. Sometimes they seem to be stuck to the thicker gasket (both items are part #6 on the diagram I posted. David
  11. How hard to find are the diaphragm arm & spring to obtain? I seem to recall from a thread last year that Webhead had no stock of the spring. Most of my damaged/spares carbs are missing these or have the wrong type of arm, I expect to find more missing carb parts when restoring other engine & tools in my collection in the future. I'm going to order some new check ball bearings on ebay as I've found I don't have any of the correct size for O&R carbs in my spares. I will have to make a roller, it should be possible to make the later style of disc (the smaller one that was stuck to the diaphragm). Please can you confirm if the other parts I mentioned in the last post are missing from your carb. David
  12. OR dynamite 410

    Have a look at the Newbury show thread, the Dyna-Mite generator can be seen in some of the pictures from Paul's O&R display there. David
  13. A have a few damaged carbs, I will have a look tomorrow to see if they still have the parts needed inside, any of the small parts inside can occasionally be missing if someone has been in there before. Looks like the check ball for the valve will be the larger of the two types used, most are 3/32" diameter except for early ones which are 1/16". An O&R service bulletin recommended fitting a new one during repair, as they had problems with them sticking even after cleaning. Stainless & chrome steel balls for bearings are still available in imperial sizes. I can't see the small roller that sits under the end of the diaphragm arm spring, the size is 0.062" diameter, I did make one for my first engine from a piece of rod salvaged from a broken cassette player. Also I can't see the clear plastic check valve gasket, early carbs had one made from the same black rubber material as the diaphragm. See the picture below showing a laser cut replica, thanks to Wallfish for providing me with some of these. You may want to change the exhaust gaskets, as they tend to leak when reused, not something you want when you've cleaned everything up, I found out the hard way with my first restorations. David
  14. Just a go a making some tank lid seals using a couple of offcuts of gasket paper. Nearest hole punch I have in my kit is 26mm and I used 1/16th punch for the vent hole, took a little searching to find a lid without a seal to test fit it with. Anyone know the best thickness of gasket paper to use? I have gasket paper in the following sizes, 0.006" (0.15mm), 0.01" (0.25mm), 0.016" (0.4mm), 0.031" (0.8mm) and 0.063" (1.6mm) I don't really want to damage any originals to find out. David
  15. I suspect if you use ordinary card to make a seal for the tank lid, it will fall apart when it gets wet with fuel and end up in the bottom of the tank. David
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