EvilC57

Ah yes. Thanks chaps.

I've recently noticed these marks on my 5m tape measure. A black shield at 16" and every 16" thereafter. A black diamond at just after 193/16" and just after every 193/16" thereafter. A black inverted shield at 40cm and every 40cm therafter. Any ideas as to what they signify please?

That's good to hear Jon .

Another update by OP: Crank pin further cleaned up using some very fine wet & dry with oil as suggested by Jon in an earlier post. Engine reassembled, and then tested by having a tank full of fuel put through it at our field today (both right way up and inverted), as you can see below. On getting it home again, I removed the crankcase lower housing once more, and everything including what I could see of the crank pin appears to be covered in a fine coating of oil - which is good I guess! It’s now back in the model awaiting some more testing on the ground, to rebuild confidence before it takes to the air again. IMG_5335.MP4

I agree with you Jon about the half turn being madness. I’m talking about one or two clicks, that’s all.

Going back to this earlier post. May I just defend myself: By saying that I run engines on the rich side, I'm following the manufacturers instructions; in that as per the instructions for both 2 and 4-strokes, I run them slightly to the rich side of peak RPM when on the ground. I.E. In accordance with the following diagram, which appears in the instruction manuals for a number of OS engines. And also: The instructions for the RCV58-CD which say, "Main needle (high speed) adjustment: The main needle should be adjusted with the engine operating at full throttle. The engine should be leaned out until the RPM peaks, then enritched a small amount. This will allow for the leaning out that normally occurs in flight.". The instructions for an OS MAX-25FSR I also own, which say, (after running in) "After six to ten flights, it should be possible to run the engine continuously on its optimum needle setting. This setting is with the needle valve adjustment 1/4 to 1/2 turn on the rich side of the position at which the engine reaches its very highest speed. Your engine can be said to have completed its running-in period when it holds a steady speed at this optimum setting. Never attempt to gain a few more RPM by running the engine on a lean setting; it will run hotter and may eventually become damaged by over-heating.". I'm just doing what the books say .

Yes I did. I picked off the remains very delicately with a scalpel, and used a small soft wire brush afterwards. I didn't want to attack it with wet & dry and risk reducing the diameter. It looks (under a x7 magnifying glass) and feels completely smooth now. The brass washer from the crankpin was more of a problem. That had some stubborn deposits of aluminium from the old conrod on one side of it. This I cleaned off using very fine wet & dry (used wet) in a circular motion on the end of my finger against a smooth surface. Being careful to remove all the aluminium, but none of the brass. I can only do what I can do to ensure it's perfect during reassembly. If it fails again it'll go in the bin, and I'll turn my attention back to eBay for a replacement engine.

No I'm not sure. The cylinder bearing is running smoothly now, and my understanding of other people's efforts at replacing it leave me a little reluctant to try it unless I have to.

Right, time for an update and some questions. I decided after all that as it seemed only a new conrod was required, I’d go for a careful cleaning of the the engine, followed by an equally careful rebuild. I managed to remove the rotating cylinder with the aid of a heat gun, a small wooden drift and a rubber mallet. The large ball race then being exposed. This felt slightly gritty, and on washing it out I noticed a fair amount of what looked like aluminium swarf in the bottom of the plastic container I used as a bath. The bearing still felt slightly gritty but was perfect after being kindly blown out by a friend with a compressed air line. Fitting the new conrod with the lubrication cutouts at the front, as suggested by Martin Harris and others in the thread suggested by Manish just above, gives the conrod an offset toward the front of the piston (see pic below) - I know the crank pin circlip is not fitted yet. Can this be right if it’s not in the the middle below the piston? It could be argued that there should be another washer forward of the big end, however none was fitted originally, and no washers at all are shown on the manufacturer’s exploded drawing of the engine. Looking at the remains of the old conrod compared with the new, you could almost believe there was no oilway in the big end. Once the rest of the engine is sorted, I might try filing into the remains of the big end to see whether I can see any trace of the hole that should be there.

However, I've just remembered a thread I started here a while ago. Make sure the receiver has the latest software installed.

It would appear so. I took the pictures below while on holiday in Tibet a few years ago, where it is a sacred symbol in the Bön religion (a minority branch of Tibetan Buddhism), and predates its use by Germany by hundreds of years.

Yep, I have several of them in use with my DX8 Gen 1.

Yes, I’ll strip everything down as far as I can and give it all a thorough wash out; presumably in fresh fuel being the best thing. Unless anyone knows better, I can’t get the rotating cylinder valve out, as looking at the exploded diagram here it seems to be retained by a large circlip, which once installed in the upper crankcase casting, can’t be accessed to remove it.

Who knows? That was my thought too. As I said in an earlier post, it is inverted in the model. But the instructions specifically say it can be run inverted (like every other glow motor I’ve come across). I’m careful to run engines on the rich side. I’d rather have the reliability over absolute peak RPM.