Member postings for Braddock, VC

I've always had good service from KLMS.

Charlie, one of the staff there is on rcmf.co.uk as a mod, maybe try on there.

Remind me when you came to my flying field and observed my engines running, don't seem to be able to recall that.

I can recall your diagnosis of rc plane flyer's irvine 46 which, to be honest, was wide of the mark.

Now how shall I regard your advice? I think I'll pass.

If you want to use a laser inverted with the tank on the prop centre line with no problems, modify an old strimmer carb or similar e, buy a set of gaskets for it so you have a repair kit if it becomes necessary.

The modification is straightforward, first I will explain the reasoning and then general guidance which any modeller worthy of the name can follow.

The carb as fitted to a petrol two stroke is pumped by crankcase pressure, this oscillates the diaphragm until the pressure on the fuel side equals the pressure on the pump side and the situation will stay like this until the engine is running with no fuel leaking through the carb. When the engine starts running, the vacuum on the upstroke of the piston causes fuel to be drawn through the jets and the pressure on the fuel side of the carb drops, the diaphragm valve is pushed over to allow more fuel into the carb and thence to the engine.

To modify it, we no longer have the crankcase pressure to operate the pump side of the carb, so a nipple must be installed (if the carb is bolted direct to the block with a passageway through to the crankcase) you can install the nipple by tapping that hole, some carbs, like on the range of engines made by evolution, have an adaptor fitted so you won't have to do that.

You no longer need the jets so these can be shut off completely by screwing the H & L needles closed (I prefer to dremel the heads off once this is done to prevent fiddling but it isn't necessary - I also remove the throttle and choke assemblies too).

You now need to fit a nipple into the carb casing on the pressurised fuel side, a 3mm hole and epoxy in a 3mm alloy tube and the most of the work is done.

The old mounting holes can be used to fasten the carb any where convenient, connect up the fuel outlet to your carb and the nipple for the crankcase pressure to preferably your exhaust pressure nipple on the engine or to the crankcase vent on a laser via a T piece, the open end of which you reduce in size, if it's plastic, with a hot soldering iron, if it's metal by crimping.

Choking the engine will draw fuel through and when it's started the pressure pulses from the engine will pump the fuel, the little flap valves in the element will prevent fuel flow when the engine is stopped.

I can assure you it will pull fuel from about 8" away from the engine, I fitted one inverted in a WM midget mustang with a laser 80, that's where I learned to crimp the open end of the T piece.

I also used it on an OS 160 Fx on crankcase pressure at first then on silencer pressure as I was plagued with leaks from the crankcase, using a drilled bolt via one of the backplate mounting screws on through a 1.5 mm hole into the crankcase.

I gave one to my pal at the flying field who had a super tigre 20/23 that was plagued with dead sticks, his tank was about a foot away from the engine and he took the pulses from the silencer, the dead sticks stopped.

You can pick the old carbs up for free if you know the proprietor of a lawnmower repair place, couple of quid if he's tight.

I forgot to say that you leave the fuel inlet nipple where it is, but you knew that anyway, didn't you.

I can't claim responsibility for this idea, it was published in one of the mags from when we had a choice, modelflyer I think and was passed on by the editor Ken somebody or other I think who used it on a laser 150 iirc, but I can't remember if he used crankcase or exh pressure.

As fuel is only supplied on demand it won't drip when stopped, flood the engine etc.

Going back to the OP, what about the OS 200 Surpass?

Just a satisfied customer, the p&p is free too.

simplybearings.co.uk

Go for it and let us know how you get on. I would imagine that any engine designed for UAV operation will be 100% bullet proof as the prime mover for a model.

Have you got it back together yet?

TBH the parts I ordered to repair my 72 aren't with me yet....

Have you got it back together yet?

TBH the parts I ordered to repair my 72 aren't with me yet....

Ideal for throttle servos then .

That link is 9 years old.......still valid though, the size of the output shaft gear teeth will probably have an adverse effect on the resolution of the servo I would have thought.

I also have faith in corona and turnigy servos which have never let me down in service.

Edited By Braddock, VC on 23/05/2019 10:52:31

I know some JR servos are 4.8 volts only, I ditched all of mine as I use 2 cell LiFe batteries exclusively for my rx. I had a couple of jr servos let their smoke out being the reason.

Well done, it reminds me I didn't offer up the one tip that may have helped with that, aerosol carb cleaner, the kind used to clean carbs, this will shift most crud and, if necessary, you can use it to clean the Mass air flowmeter on your petrol car where the results may surprise you.

Percy, a little story. Wife and I went to the pilot at dungeness coinciding with the school run, I watched a boy breakdancing (?) along the pavement in a world of his own. I told my wife I remembered doing something like that one time when my school broke up for summer hols and I walked straight into a gas lamp post that floored me.

Happy days.

As I mentioned, it dates back a quarter of a century, pretty confident that predates Chinese copying techniques.

I generally phone. If it's in Ripmax catalogue online generally it's available so you should be ok. Irvine parts are what's left after they ceased manufacture. You may be ok with the OS made engines as they tend to produce parts for some time.

Removing the Conrod can be difficult, quite important to get the top end of the rod toward the rear of the gudgeon pin then and grasp the rod with an L shaped tool near the big end, it should come off. Remember to mark the rod so it goes back the same way it came off. Some Irvine's have an oil hole drilled into the bronze bearing and this face of the rod should face toward the crank web.

If all else fails grip it with a pliers and pull, it HAS to come out. Any damage caused by the pliers can be dressed with some form of abrasive, as long as it's smooth it should be ok.

Please remember it's your engine and my advice assumes competence, if you damage it in any way it's your responsibility not mine, I'm just telling you how I do it.

Remember anything you read on the web is 99.9999% bull I just may be the odd 0.0001% or I may not 😉

Edited By Braddock, VC on 22/05/2019 23:56:29

I have a great deal of confidence in futaba servos and I was sorting through my servo box tonight to come up with 5 for my soon to be completed Modeltech Cub.

Managed to get 4 S3001s and a handful of s148s and popped them all on the servo tester.

One of the 3001s had a problem with the gears and one of the 148s wouldn't work at all.

Twas the work of 5 minutes to swap the gear trains over and now I have 4 working 3001s and one 148 for the throttle.

I wondered why the 148 that I'd cannibalised had failed and there was no sound from the motor so I pulled the bottom off to test the continuity of the lead when I noticed the signal wire had broken free of the soldering to the pcb.

I could have soldered it back but I cut the lead off completely for future use and dumped it as I hate having 1/2 servos and, as I'd had it since 1994, it didn't owe me anything.

Whilst writing this post I remembered I have a couple more suspect 148s so I pulled it back out of the bin and when I get a moment I'll check out the three of them and see if I can get at least another one working.

To be continued...............

Percy, you and I are in the minority. I have to say that I prefer my kids engrossed in their phones than smoking which was the pastime of the young many years ago.

I also note they don't pick their noses as much as kids in my day .

Wouldn't bother contacting ripmax, sussex model centre will do all that and charge you ripmax prices.

Just engines don't do an aftermarket liner for irvines I think it's safe to say, they used to do one for the OS Fx series but I think they don't do one for the Ax series now, maybe wrong though.

Bottom

PS I'd get the gudgeon pin as well it's peanuts. Delamination usually starts at exhaust side following insertion of something hard enough to crack the plating through the exhaust port whilst jacking out the liner eg when replacing bearings .

Use only wood or plastic.