Why does this happen?

[David Davis]

I have been flying model aeroplanes for decades and consider myself to be quite good at setting up engines but this is a good one for the cognoscenti.

I own a red Irvine 46 which I bought second hand, fitted in an ARTF Stick 1500.

The engine runs perfectly, pulls like a train through all of the manoeuvres I am capable of, throttles beautifully and ticks over very reliably. The problem is that it's a pain to start.

Having brought up fuel to the carburettor,attached the igniter to the plug and reset the throttle to a fast idle, I find myself having to grind away on the starter for several minutes before it will fire. Once it has fired and attained operating temperature it's fine.

Any ideas why it won't start easily?

[Jon H]

If its really cold you might struggle. And all the usual ones about how bright is the glowplug, is it a new plug etc etc

One thing you could try is squirting some fuel down the carb directly. The tank is quite low so it might not be getting quite enough fuel for the initial start up. 

That said, a friend had one of these in his trainer and it did exactly the same. We all got so fed up with the stupid thing we dropkicked it into the weeds and stuck a 52 4 stroke in it. That was much better.

Edited By Jon Harper - Laser Engines on 18/01/2017 09:06:40

[Denis Watkins]

Talk about teaching your granny to suck eggs David, we know your depth of knowledge from your writings. OK, any IC motor, correctly fueled, plug and plumbing, will start on IDLE, no amount of high needle required. OK, it doesn't start. These motors are notorious for a leaking front bearing from being fairly new. It is annoying, but a leak of pressure on any 2 stroke leads to tuning problems. Consider that as one reason, is it very oily at the front?

[Peter Christy]

I've always found a decent sized ammeter in the plug leads an excellent starting aid. A 5 amp meter with a decent size scale (think old car battery charger!) will give a good indication of whether an engine is dry or wet.

For example, most of my models use OS No8 plugs, which normally draw around 3 amps. If the engine is flooded, this will rise to 4 or more amps. If the engine is dry, the current will rise slightly when the engine is cranked by a starter, dropping back when you stop cranking.

You need a decent size meter to be able to read these differences, the tiny things on most glow sticks are useless, other than as a "glow - no glow" indicator.

Any IC engine with compression, fuel in the right proportion and ignition of some kind will run. If it isn't running, its because one of these is missing. In the OP's case, I would guess the engine is dry, but an ammeter in the glow lead would quickly confirm this.

--

Pete

[Keith Berriman]

I have had, and still have two Irvine engines and yes on the first start up take a little longer than you would like.

Having tried various plugs the best one I have found for the Irvine engine is the Just Engine no R 4. I use a large

D Cell Nicad and no problems with low tick over . Definately need a blocked open throttle and 6 turns backwards to prime the engine

[ken anderson.]

hello David.............. I have this problem with my small ic engines.....I put it down to old oil left in the carb needle that has congealed etc...once the engine has a good hot run its good as gold...but if left for a few weeks/months I know what to expect...try pinching the fuel line on the last flight run up...to suck all the fuel out.... .... long shot..may help.

ken Anderson..ne.1 ....longshot dept.

[Engine Doctor]

The post by Dennis Watkins has probably nailed the problem. The front bearing as supplied are sheilded and will not hold pressure . As secondary or crankcase compression is more critical in a two stroke than primary or cylinder compression this loss of compression will make the engine hard to start as little fuel air mix will be blown through the transfer ports to the cylinder. As Dennis says this condition is accompanied by an oily front end where unburnt fuel is blown out into the prop wash. The problem is not caused by the bearing but crankshaft to crankcase fit or design as many other two stroke engines use shielded bearings with no problems. Fitting a sealed bearing should cure the problem . You can remove the inner rubber seal if you wish but on these engines I leave both seals in place and have had no problems after many hours of use. The bearings are similar to those used in car alternators that last for years with considerable pressure on them from the drive belt with only the factory lubricant fitted with no problems. Try changing it and let us know the outcome.

[David Davis]

Thank you everyone. I haven't noticed it leaking oil from the front bearing but will get round to changing it when I get a minute. Any idea of suitable suppliers?

[Keith Berriman]

Hello David. Look up Model fixings. But check the bearing size first as there are various for the Irvine engines

[GONZO]

I vote for the front bearing being the problem. A sealed bearing from modelfixings or simplybearings will get it sorted. Increasing the crankshaft to crankcase clearance is a way to improve performance by reducing the drag. But, go too far and it gives problems.

[Peter Beeney]

David,

Once upon a time I flew a Chippahawk with a Moki 61 two stroke up front. This was a super engine, very much suited to the equally super Skyways model. The only problem with it was that through the autumn and winter months it simply just would not start under any circumstances. I tried every trick that I knew, including priming with a drop of Keil Kraft diesel fuel but always to no avail; the best it would ever do was an infrequent pop in the silencer. I soon concluded that there was little wrong with it because it normally ran so well; and having read the stories about the difficulties starting full size in the extreme cold and also previously watched my colleagues starting their diesel lorries early in the morning in the depths of winter during the late fifties and early sixties, they would get the gas blow torch going and warm the inlet manifold up I eventually had a rethink. Part of my work kit was a small Primus gas bottle/torch so as a very last ditch attempt I lit this up and warmed the very reluctant beast up. Lo and behold, one flick and it was away!! So this instantly became the order of the day and it was always a total success, I soon discovered that a few moments concentrating on the crankcase was sufficient, I could only surmise that it possibly helped any neat fuel to vaporise sufficiently to get that first firing stoke in. In those days I was a member of a popular busy club so you can imagine the ribald and fairly derogatory type of remarks that frequently accompanied this procedure; but I usually got my own back because it always started straight away… I even got proficient in doing ‘hot’ refuels, i.e. without stopping the engine; although I have to say this was probably just really just a bit of unnecessary bravado…

Whether this was a one-off Moki or whether they are all the same I do not know…

The model met it’s end in a midair with a small biplane on it’s maiden flight. His prop cut right though one wing near the root and it crashed heavily on a tarmac runway which broke just about everything. The runway was fairly big, but when you consider it as a percentage of all the surrounding acres and acres of grassland… Typically his model was undamaged which was at least one consolation and as with the other two midairs I’ve had there were only two of us on site at the time.

Like many other modellers I’ve owned a number of Irvines over the years, from the first 0.40 with the Dykes ring, but from memory they’ve never been significantly difficult to start…

Hope you manage to fix it without any more delay…

PB

[Don Fry]

David, I take it it's only the first start of the day is the problem.

I have had a couple of these, 46 and 52, all older British built red ones. I too find they are not the best starters on the day's first start. Instant starts thereafter. I find they don't appreciate after-run oil from the last outing. (Tough luck, its good for you). They all need a good squirt of priming fuel, or even 2 squirts, into the Venturi, and then run through the engine before bothering with plug heat. When well wet through, they start.

Can't say I have noticed front bearing problems. The 52 had done a couple of hundred hours when I destroyed it in a disorientation incident. It was nicely run in to my mind and giving no sign of wear.

[Steve Hargreaves - Moderator]

Could it be thatvthe starter is simply spinning it too fast for the throttle opening? If the throttle is set for 2500 rpm but the starter is spinning it at 3500 rpm the fuel mixture will either not be there in sufficient quantity for the engine to run.....try opening the throttle a tad.

Alternatively might the glow be a little weak? Are you using a NiMH cell to power it.....? A good old 2V SLA can often effect a complete cure.....

Or might it simply be short of fuel.....? Some engines do like to be quite wet before they will fire up...

[kevin b]

Short answer to the original question.

Because its British.............and not a Laser.

[Dave Bran]

I have an Irvine 39 that has done the cold start reluctance trick for years. otherwise its perfect and is actually quite reluctant to stop, with a ridiculously low idle it has never ever stalled from.

I have given it no love at all, its never had oil, never even been run out on ceasing flying, cannot remember when I last touched the needle.

It does start faster if well primed and left on idle throttle.

It's bullet proof once that first start is over with, SO I leave well alone!!

[Dave Bran]

Posted by kevin b on 18/01/2017 20:34:17:

Short answer to the original question.

Because its British.............and not a Laser.

Because it's British, and not a (spit) four stroke.

[J D 8]

As a long time Irvine user [70's] I also agree a good squirt of fuel in the venturi and away they go.

[cymaz]

 

 

 

 

I use this method to start my two strokes...have done for years

 

https://www.youtube.com/watch?v=NNFf0OyAdpw

 

Edited By cymaz on 18/01/2017 23:00:35

[cymaz]

Sorry for the lack of short cut...my iPad has decided to throw a hissy fit...

[Former Member]

[This posting has been removed]

[Peter Jenkins]

The Irvine 53 Mk 1 had an O ring between the Carb (black not the Mk 2 silver) and the crankcase. If the 46 is the same have you tried loosening the clamping bolt, re-seating the carb and then re-tightening the bolt while pressing the carb down onto the O ring. Alternatively, replace the O ring and then re-tighten as above. Sometimes, you get an air leak if the O ring has perished or the carb is not seated tightly onto the O ring.

The other problem is old fuel. I've had that problem but then again it won't idle reliably either and as you say it works fine when hot perhaps its not the fuel. Worth considering though.

[onetenor]

In the early days 2 volts from an ex gpo or similar wet cell was the order of the day You could see the glow on top of the wet piston and hear the sizzle too .This may burn out modern plugs but 1.2 volts seems a little low for my liking and Nimh cells only seem to produce a red glow on plugs I have tested.A good dry cell is somewhat better but nowhere near as good as a wet call.There are gel cells now at 2 v and I recommend one of these .My MDS an d Irvine 61's both start easily with 2 volts as do do my Cox's and other motors I have I modded the Coxs to accept seperate p lugs

[Peter Beeney]

One trick that’s been tried many times when winding up a reluctant motor is to just place a finger momentarily over the silencer outlet to increase the tank pressure and force more fuel into the spray bar; however, this needs plenty of caution at the same time because it could result in the crankcase quickly becoming over flooded; generally it’s a very brief affair, say for only up to a second, at least initially; an overly flooded crankcase and a energetic starter motor might not really be the ideal combination with which to start the day…
Having now said all that, this simple little strategy more often than not results in an instantly reassuring burbling exhaust…

I like to see a nice bright glowing orange plug, I’ve always thought this does help with starting so I’ve always used a 2V lead acid cell as the power driver. For some time now my source has been an 8Ah Cyclon cell, this is very portable but it will maintain it’s 2V output for a long time and in dire conditions. Mine is often borrowed to help out when items such as power panels are suffering from voltage drop and other ailments, particularly in the winter. Which bring me to the next point, I always tend to try to impress on beginners the importance of keeping all their batteries fully charged, especially during the cold weather because this will soon expose the laggards; it’s very discouraging to spend a long time trying to start an engine and then finding the plug is rather dimmer than yesteryears proverbial Toc H lamp… …and I suspect that it helps to be of a certain advanced age to fully appreciate that remark, too…

I’ve found that a short time spent giving the engine a little bit of help in the starting blocks usually pays dividends, then it mostly becomes a first or second flick jobby.. but there are exceptions, such as the Moki, (a few posts above). One or two modellers I’ve noticed seem to be quite content to just connect the glow and then continue to crank it on the starter until it eventually fires…or doesn’t… This is a bit too much like hard work for me…

In a case like David’s I think I’d be tempted to concoct a little priming bottle with an extra dollop of castor oil added. This might at least help the piston seal when it’s cold and consequently the compression and the induction; and if it doesn’t do the trick there is no harm done, either. I’ve not used castor fuel for years but I always have a small bottle handy because I add a modicum to the first tank when running in; but even then that’s only really for a bit of insurance perhaps…

PB

[Former Member]

[This posting has been removed]

[Peter Beeney]

Tom,

If I remember correctly the Fox plugs that I favoured way back were 1.5V, I still used the 2 volt cell though, I just adjusted the length of the lead until they were nice and hot! I think most of todays plugs most be about 2V, I’ve never had any problems with them, at least not as far as the power supply being too fierce. My cell in those days was exactly as onetenor says, a small 2V wet lead acid…

I’ve done a fair bit of tinkering with plugs in the past anyway, such as checking power consumption etc. and in general they are quite hardy creatures, although they do tend to rather take the hump a bit when my colleague has plugged his glow lead into the 12 volt starter outlet on the power panel. I’ve suggested that he should change the connectors on the leads in order to polarise them but so far there’s been little progress.

There might just be a tiny point here. When I attach my glow lead to a loose plug the only form of heat sinking the element has is the body of the plug; and if this is left connected and lit up for a fair period of time it can all get finger blistering hot. But when it’s screwed into the cylinder head that must act like an efficient heat sink, at least under cold starting conditions. So I’m wondering if this might make any difference to the brightness of the glow. When the supply cell is in good nick I suspect most likely not, but when the voltage is beginning to sag a bit and the element is only just about a weak glimmer anyway…

The next time I’ve taken a cyl. head off for any reason I’ll do a bit of tinkering with this theory and see if I can establish exactly what, or if indeed anything, does occur. Certainly a soaking with raw cold wet fuel will dampen things down a bit, too, but fortunately electrical principles being what they are, the element’s resistance now goes down and the current flow therefore goes up and thus quickly brings the element back to all it’s illuminated glory… indeed, I’d now consider the same thing probably applies with the plug normally installed, the heat sinking effect just flattens the glow battery a bit quicker…

As I remember too, the first new glow motor I owned was a Veco 19, circa 1959/60, this had a throttle coupled to an exhaust baffle which moved across the open exhaust port as the throttle arm moved. No silencers back then! This covered the port when the throttle was shut, I believe in an effort to try and make the slow running more reliable. This was for R/C use. This also had a 1.5V plug too, because I can remember having to buy one of the large 1.5 volt dry cells of the times; I think those batteries were also used for powering radio sets.

PB