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Member postings for Jon - Laser Engines

Here is a list of all the postings Jon - Laser Engines has made in our forums. Click on a thread name to jump to the thread.

Thread: Laser Engines - Technical questions
17/09/2019 16:08:32

I always recommend messing with the setting as there is no way i can set it right from the factory to suit every model.

Good to hear its working though.

17/09/2019 10:41:30

The correct settings on the needle are the settings at which the engine runs correctly. What those settings are for your engine in your model is anyone's guess

To be clear, starting at 2 on the main and 7 on the slow will more or less guarantee the engine will start but it will still need to be tuned up from there.

So much depends on the specific installation you have in the model and then obviously things like prop, plug and fuel all play their part as well.

When i took my 300v out of my La7 and fitted it to my P39 i had to make huge changes to the settings even though both models had the engine inverted and i was using the same prop, plugs and fuel. Just the fuel system setup was different and it made a huge difference to the needle settings as the mains went from only 3/4 open to just about 1.5 turns open. I cant remember what the slow runners did, but they moved a bunch as well.

The fact that your engine was working in the model and now isnt suggests a fuel system problem or a blockage. I have this exact issue with the right cylinder of the 300v in my P39. It keeps going out after about 6 minutes in the air and as the engine has been reliable for years and cleaning the carb has not fixed it then there must be something wrong with the tank or plumbing. Clearly you are in the same boat.

playing with the idle needle is not a problem, in fact many issues can be fixed with a slow run needle adjustment as they can creep over time. If the original settings have been lost it should be a very quick job to fix it as the engine will usually tell you everything you need to know.

If you have compression, glow, and fuel the engine will fire. It might not run, but it has to fire. If it wont fire at all one of those 3 is missing.

If the engine runs for a short time and stops, especially if you prime it before the start, again the engine has told you the problem and is waiting for you to fix it. Simply put, it ran on the prime and then exhausted its supply of fuel. Clearly it needs more fuel at idle, and that is controlled by our good friend the slow run needle. Just open it a bit and try again. If that isnt enough, keep going until it works!

I keep meaning to try and shoot a video showing how to diagnose this sort of thing but its both difficult to shoot and i am too cowardly to stand in front of a camera blush

Thread: Thinking aloud about Spits...
12/09/2019 17:23:11
Posted by Foxfan on 12/09/2019 15:36:06:

No, for me, the big ones are less attractive, much more expensive to make and power (and cover). They are pigs to transport in an ordinary small car and even more of a pain to store. The day I spend anywhere near a grand on a toy 'plane is the day you take me off to the funny farm.

It stands to reason they're easier/better to fly. I just don't much like them. Never have. I grew up with 4 footers and that's my limit with the exception of the 2 (removable winged) trainers I have. Even so, they're a pain to store in my little shed, although a bigger shed is coming, but that's no excuse to have bigger models.


I only have a normal vw golf size car. Good enough for 3 models of 80 inches without any trouble. Its just a bit of a game getting them all in! Again storage of 5 80+ inch models is easy enough in my 1.8x1m storage bunker. My 50 inch biplane is much more of a pain to store as i dont take the wings off it.

As for price, a grand on a model is easy these days and i actually had this conversation with a friend a year or so ago. He used to fly foamy's and said at the time that no power on this earth would make him spend more than 500 quid for a model. This came up as he is putting the finishing touches on a £1500 thunderbolt and has 3 other models in the 700-800 category. I suspect we would all wince if we added up the cost of our hangars as 3 cheap foamy's can get you up near 700 quid by the time rx's and batteries are accounted for.

Ultimately, no model will ever make its money back. Its just a matter of how much you are prepared to pay to enjoy the hobby. For me my 9 year old La7 of probably £1200 has been well worth the spend as i have enjoyed flying it over a long time and i feel that it now owes me nothing. My Similarly priced sea fury is not there yet after only 5 years so i would feel i didnt get my moneys worth if i lost it tomorrow.

As i allow myself a 'toys and fun' budget for the year of about £1300 (to cover all model purchases, club fees, airshow visits, pc upgrades etc) a model of that nature is a years worth of work in financial terms. The only reason i have so many isnt because im rich, its only because i do my best not to break them.

12/09/2019 13:13:39
Posted by eflightray on 12/09/2019 10:54:30:

To me bigger planes are so much more enjoyable to fly, (and easier to see), don't necessarily right off going bigger.


Absolutely right.

This is why i have settled in the 70-90 inch warbird bracket as they fly well, look great, can handle the added weight of retracts etc without getting over weight and they are still small enough to transport with a normal car. While more expensive than a 60-65 inch job, they arent that far up there as you could easily blow a grand on a 60 size model so 1200 on an 80 inch job is hardly a disaster...As long as you dont crash it.

The cost is only a concern if you are likely to break it before you stop enjoying it.

12/09/2019 09:23:45
Posted by Denis Watkins on 12/09/2019 09:10:45:

Such fine margins Jon, On spinning in like that, or going off straight

Absolutely practice progressive throttle and correct elevator input on these types

Yup, especially with the big radial he had. All that torque needs careful management.

Most of my warbirds are 50cc class and in the case of my sea fury in particular if i abort a landing after a bounce i cant firewall the throttle as full right rudder and aileron will just barely hold it in a 45 degree left bank which is a super dodgy position. That is why i only use half throttle for aborted landings as any more may spin the model.

Similarly my P39 needs full right rudder applied for the first half of the takeoff roll and i still hold some in on climb out as its not yet up to trimmed speed.

12/09/2019 08:45:09

A bit late to the party here but plenty of the comments are spot on.

Spitfires, and warbirds in general, are not difficult to fly but do not respond well to the type of flying a trainer or sport model will tolerate with a smile. I am always a fan of a steeper approach with a warbird to keep the nose down and prevent the inevitable stall you get with a flat/powered approach hung on the elevators.

I have not actually owned many spitfires but the two i have flown were both a delight. Admittedly they were both 88inch 5th scale jobbies of 20lbs but they were easy to fly and very easy to land, more so in fact than most other warbirds.

In the video below, our unfortunate corsair pilot holds full up elevator more or less all the way through his takeoff. He was so worried about a nose over he forgot all about flying the model. His lack of directional control on the takeoff roll didnt help either as there was a yaw component going before the model even left the ground. If you cant takeoff in a straight line then practice that before getting a warbird of any kind. Once a model is rolling forward at walking pace its rare it will nose over to let the tail up. once there you can wait for as long as the runway is to ease it off the ground. 

Edited By Jon - Laser Engines on 12/09/2019 08:46:14

Thread: Propeller problems perhaps?
11/09/2019 09:32:27

I would say 13x4 is a bit small. I would use 13x5 and not worry. I know ASP52's run well on that and in my experience they perform much like an os48.

Thread: IC or Electric for Ripmax DeHavilland Tiger Moth
10/09/2019 18:47:50

Mine was happy on a 30. It would fly perfectly well at half throttle or less so while the 40 would probably be ok its not a requirement.

dont use a 52 though, way too big.

10/09/2019 14:07:16

If you go for the 30fs then use the biggest prop you can but with a fine pitch. I think i used 11x5 but i cant remember as it was a while ago.

09/09/2019 14:59:54

what is the span/weight? i had a perkins/green air 50 odd inch tiger moth some years ago and it flew really well on a 30 4 stroke. As there are not many 4 strokes that size any more you might have to electrocute it

Thread: YT International anyone had recent experiance
07/09/2019 21:01:25

I have 3 airworthy YT warbirds and 3 more to build. My appraisal is as follows:

The good.

They fly well, look great, are quite robust and (if you dont crash them) last a good number of years. My 3 flying models are 9, 7 and 6 years old if i remember rightly.

The Bad

If you expect to shake the box and have model build itself think again. They need a great deal of tinkering to get things to fit right, fix small defects in manufacture and generally improve the whole deal.

The instructions and some of the supplied hardware leaves a little to be desired.

They can end up a little porky if you are not careful. with the placement of your stuff.

As for availability i think they have stopped producing kits but some ESM (the brand of kit they sold) models are still available from

Thread: OS 40 four stroke, inverted?...
06/09/2019 23:57:07

i would say that the tank in pat's example is in fact too high. I would set it up as cuban suggests and essentially have the top of the tank level with the spray bar. This prevents a change in head as fuel is used.

06/09/2019 19:08:51

i agree with everyone else. Inverted should be no problem as long as the tank is in the right place. Make sure the tank isnt too high as the air bleed carb on the little OS will not tolerate a high tank

Thread: Morris gas conversion experience
06/09/2019 13:53:21

I love their enthusiasm, and as it happens it sounds pretty good. Transition is slow/rich but not like the other video.

Its a hefty old unit bolted on the bottom though. Its like another whole cylinder!

06/09/2019 12:25:06

A perfect example of the problems with these conversions. Flat out they can work, but low throttle is usually a mess. From the sound of the idle its only running on one cylinder and you can hear the other two come in as the throttle is opened up.

05/09/2019 20:41:17
Posted by flight1 on 05/09/2019 20:10:02:

the asp is not noisy like a 2 stroke engine and if you use a baffled silencer on each cylinder you will find the noise to be very amicable. two asp .60 size baffled silencers with suitable manifolds will do nicely or make your own.

as for fuel I don't know what you use down under but 15% fully synth modern oil works fine, once run in and if you like straight fuel and know what you doing a lower oil content can be used

Quite right. What i mean is other multi cylinder engines have a nice sound on straight pipes but from some reason the flat twins i have experience with sound really harsh. One is an OS ft300 and it was unbearable. I bodged up a pair of exhausts with parts from work and it then purred like a kitten.

As for fuel, 5% nitro and 15% synthetic is my starter for 10 on all engines these days. As the conrods are pure bronze in the 160 you would likely be fine with 10% oil and probably even as low as 5%. I have not yet run mine on anything less than 15% but there is loads of oil coming out at 15 so i think i will go for 10% when i finally get around to using it.

05/09/2019 15:35:32
Posted by Ted Khinsoe on 05/09/2019 15:15:52:

It’s slated for a 1/4 scale L4 Grasshopper so as long as it stays running I’ll be happy.

that is what mine was for. A friend and i both had models but his crashed before i built mine. As we wanted to fly them together i abandoned the project but kept the engine.

Piers, if there is interest i will step it up in priority from 'one day it might be fun' to 'something for the winter'

One final gripe about the engine is the sound...its awful, or at least it is on the bench. I have two flat twins (160 and 300) and they both sound extremely harsh when unsilenced. My now sold 3 cylinder saito, my 5 cylinder asp radial and OS flat 4 sound fine on straight pipes but for some reason my two flat twins sound really bad so a pair of silencers is recommended.

05/09/2019 09:01:55

I have an ASP version of this engine and my only gripe is the mismatch between the cylinders when it comes to the tuning. My right cylinder always runs rich vs the left up to half throttle. I have never flown it due to a change of plans, but in all my test running its never dropped out at random so i dont think its going to be a problem.

After i changed projects i did set about modifying my engine so it now has laser twin ring pistons and this has helped the compression somewhat. I needs new rings though, i only had worn ones to play with when i rebuilt it.

If i get time i might convert it to twin carb as that will fix everything

04/09/2019 14:44:54

My experience has been very poor.

Many customers return their engines to me for conversion back to glow as they didnt work following petrol conversion.

My own petrol development has demonstrated clearly that its really not as simple as carb swap and ignition. At least not for the level of performance that i deem acceptable.

Thread: Cambrian Spitfire
04/09/2019 14:40:07

Yea it looks much better in that side shot

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