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New Laser engines. What do you want?

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Percy Verance18/11/2017 08:32:00
6630 forum posts
111 photos

I don't think Jon would want to bother Bert, particularly as anyone who wants to convert can simply buy the conversion from the Mini Motors bloke themselves. There used to be the Jim Shelley conversion too, which I understand worked well.......

Just Engines also offer sets/parts for conversion, but I'm not sure just how successful these are? I've never seen one running.


Edited By Percy Verance on 18/11/2017 08:37:57

Jon - Laser Engines18/11/2017 10:54:34
3826 forum posts
149 photos

Hi Paul, the 75 might be a bit big for the Bristol. I fly similar models on 45-50 4 strokes without any issue. The 75 might be a bit porky for it too. If you want a biplane, something around 70 inch would be ideal for the 75

Bert, we have already discussed it and we will not be offering conversion kits. none of our competitors do it, the cost would prohibitive, I cannot guarantee that a 20 year old engine would take to it without seizing, and I expect I would get at least 50% of the engines back to be fixed.

I think just engines offered engine kits a while back and it didn't end well.

Regarding cost, the required parts to change a 180 glow to petrol are as follows:

Prop driver, prop driver collet, crankshaft, front housing, pinion drive, backplate, fuel pump, pressure regulator, carburettor, cdi unit and spark plug.

I'm sure you can work out the prices in your head looking at that little lot.

Percy, I have repaired customer engines run on the commercially available kits and they don't run well. They run, but there are major compromises and they are pathetic compared to their glow counterparts. Part of the reason its taken me so long to sort our petrol engine out is because I was not prepared to accept such mediocre performance.

Martin Harris18/11/2017 13:02:42
7631 forum posts
189 photos

There seems to be a great regard for petrol engines but to my mind, the "humble" glow has a lot going for it. It's no co-incidence that alcohol fuelled engines are at the "exotic" end of the full sized racing world - they produce far more power per cc of capacity than their petrol engined peers at the expense of using more fuel.

Getting back to "our" engines, the glow plug provides an automatic basic advance/retard function but if the occasional failed plug is unacceptable to some, there's always the option of running them on a spark ignition system. In fact, I suppose if you were a little paranoid here, some thought could be put into revisiting the provision of a second glow plug per cylinder as per the old Mercos etc?

Yes, petrol is cheaper and requires less lubricant, but it seems that Jon is making steady progress towards approving a dramatic lowering of oil content for Lasers (at the least) and in the quantities we use, cost is not a major factor. To me, the benefits of being able to store my models in the house outweigh the advantages of petrol. I do have one petrol powered (Z38) model - it takes up a lot of space in my workshop and even though I store it with the breather firmly blocked, there's always a faint whiff of petrol when I go in there. The cost of non-smelly Aspen would negate much of the benefit of using it and I assume it would still be as volatile as petrol?

Jon - Laser Engines18/11/2017 13:31:46
3826 forum posts
149 photos

The aspen fuel has less tendency to gas off and cause a vapour so it is less volatile in that regard but clearly its still petrol at the end of the day.

For me a spark fired methanol engine is almost the worst of both worlds as you have the complexity of the spark but without the reduced fuel consumption. sure there is less complexity in the plumbing, but I think I would go either petrol or glow and not half way in between.

I will always use the aspen in my engines as its still cheaper than glow fuel, and the stink of petrol makes me sick. the fact that its pre mixed, has a long shelf life and is better for the engine are also in its favour.

Martin Harris18/11/2017 19:18:57
7631 forum posts
189 photos

Aspen is something that I've meant to try - the only problem is that the nearest supplier is a lot further from me than the local petrol station! It does cost a lot more than I currently pay for 10% glow fuel but assuming the consumption is similar to ordinary petrol, a little should go a long way.

The point I was really trying to make is that glow engines are still a very practical power source and if we can indeed reduce oil content dramatically, a technology which should have a future in the hobby.

Cuban818/11/2017 20:42:01
1992 forum posts
3 photos
I'm sure we've been over this before, but why are petrol engines ok on such low oil content, and in four stroke glows, where would reduced oil content have the most detrimental effect?

Edited By Cuban8 on 18/11/2017 20:43:02

John Stainforth18/11/2017 21:10:28
194 forum posts
38 photos


I'm with you regarding glow engines. I just can't see the merit of petrol engines below about 50 cc, and like you and Jon I can't stand the smell of petrol. The main problem I have with glow fuel in the UK is finding adequate time and weather to burn through what I have got!

Geoff Sleath18/11/2017 22:38:33
2662 forum posts
199 photos

Funnily enough (even as an almost exclusively electric flyer) I quite like the smell of petrol. In fact the smell of the really stale petrol that emanated from the fuel tanks of the very old motor cycles I used to buy and restore is one of the fond memories of my youth. The bikes had often been resting in someone's shed for upwards of 30 years so when I say stale I really mean it

My 2 models with petrol engines live in the garage mainly because of the size and are powered by 26 and 30cc 2strokes (Zenoah and Mackay). I don't think either of them has been flown this year for various reasons.


Jon - Laser Engines19/11/2017 00:06:28
3826 forum posts
149 photos
Posted by Cuban8 on 18/11/2017 20:42:01:
I'm sure we've been over this before, but why are petrol engines ok on such low oil content, and in four stroke glows, where would reduced oil content have the most detrimental effect?

Edited By Cuban8 on 18/11/2017 20:43:02

Glows should be fine on the same amount of oil. in a 4 stroke this should be as low as 2%. I tested my 100 for a year on 4% and it was fine.

the snag is, somehow some still manage to seize engines on 20% and we cant quite work out why!

Percy Verance19/11/2017 08:19:05
6630 forum posts
111 photos

Relentless needle twiddlers in their never ending quest for more revs. We've all seen 'em. At least one in every club.

Jon - Laser Engines19/11/2017 10:16:19
3826 forum posts
149 photos
Posted by Percy Verance on 19/11/2017 08:19:05:

Relentless needle twiddlers in their never ending quest for more revs. We've all seen 'em. At least one in every club.

This could cause overheating but should not cause any other issues. I lean off all my engines to the absolute max as I always want maximum performance. As long as the heat is lower than the temperature at which the oil breaks down (some synthetics break down at a low temperature) you will be fine

Ron Gray19/11/2017 10:40:11
886 forum posts
231 photos

I’m with you Geoff, I just love the smell of petrol, not straight from the can but wafting from a model or engine, lovely.

Percy Verance19/11/2017 11:02:38
6630 forum posts
111 photos

I just couldn't cope with the smell of petrol in the car driving home after a flying session. It made me feel quite queesy. The petrol engines had to go.....

Martin Harris19/11/2017 11:25:15
7631 forum posts
189 photos

I'm not sure if it's me or the changes in the additives over the years but I find the smell of petrol quite unpleasant, these days, even to the point of feeling physically unsettled if I'm exposed to too much of the fumes. I certainly don't recall these effects back in the heady days when 5 star was still available and lead-free was just a nasty rumour from the other side of the pond...

ASH.19/11/2017 11:28:19
208 forum posts

I use to work in a petrol station back in 70's when there was no self-service. I had no problem with petrol fumes then. However, I do remember the smell of petrol inside some of the cars we drove with their leaky carburettors - it was horrible! I think in a confined space the smell is nauseating.

Edited By ASH. on 19/11/2017 11:31:22

Percy Verance19/11/2017 11:34:29
6630 forum posts
111 photos

I certainly found it so ASH. I often had to make frequent stops on the way home from a flying session. The aircon did help a bit, but I still found the stink overpowering. The noise was a bit much too, but that's another story.

Needless to say, my petrol engine ownership lasted but a few months........

If I were to buy another petrol engine then it would have to be synthetic petrol (Aspen) for me.......



Edited By Percy Verance on 19/11/2017 11:44:01

ASH.19/11/2017 11:44:59
208 forum posts

That's what worries me Percy.. even with a nice 4 stroke petrol!

Off to the field soon.. it's a gorgeous day for flying. Can't wait to smell the sweet nitro exhaust fumes from my Saito. it's perfume to my nose.

Edited By ASH. on 19/11/2017 11:59:48

Percy Verance19/11/2017 12:58:24
6630 forum posts
111 photos

No flying for me unfortunately. We've just had an extension more or less finished, with just some 2nd fix electrics to complete. The electrician says he'll be back in the latter half of next week to complete, but if a job elsewhere gets cancelled it'll be sooner, so we have to be ready......

Right, must dash.......


Edited By Percy Verance on 19/11/2017 12:59:24

Bob Cotsford19/11/2017 13:04:39
7268 forum posts
415 photos

I don't think it's the smell of nitro Ash, more likely it's the oil used. My clubmates accuse me of running on chipfat (Laser 5%) and they do have a point. Those club members engines still running on fuels with some castor definitely smell sweeter!

I think the additives in modern petrol have changed the smell, I too had to drive home with the windows open after flying petrol motprs whereas a few decades ago petrol had a much less noxious odour.

Ernie19/11/2017 14:33:37
2427 forum posts
7 photos

Hi Guys

Smell? when SWIMBO needs a special favour, she wears CASTOR OIL no 5


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