Laser Engines - Technical questions

[Ron Gray]

Just another potential air 'leak' problem. I had exactly that happen to my Wots Wot XL when it had the Laser 160v in it, on take off I kept getting a lean cut which was eventually traced to air getting in through one of the filters. Removed both of them and the problems went away. 

[Frank Skilbeck]

I don't fit fuel filters on the feed and don't usually have a problem, I do have a filter on the fuel pump though. But I think the debris may well have got in the system while the engine was off the plane, that's if it turns out that was the problem.

[Jon H]

On 28/11/2022 at 16:39, Mike Mc said:

Jon, what's your thoughts on fuel tilters? 

I have them on all my airplanes to prevent problems like that.

 

 

Sorry for the late reply. Been occupied with other things.

 

The other guys have mostly covered it. We dont recommend them as they can leak and cause problems with mixture. We recommend fuel is filtered before it makes it on to the model. I use a fairly coarse filter as my fuel pickup from the bottle to get the big stuff, and then the nozzle i use to fill the plane as a very fine mesh filter. This does the trick nicely. 

 

If you have an ancient tank contaminated with castor it can flake off and cause problems. The quickest and simplest option is to change the tank. Then if you wish to rescue the old tank you can do that at your leisure while flying with the new tank. 

[J D 8]

     The only filter I use is in the model box tank. A large [ish] felt clunk which is commonly used in petrol motor mowers, brush cutters ect.  The small jets in these require fine filtering. Depending how much flying you do swap out every couple of years.

[Martin Harris - Moderator]

I’ve used (Sullivan?) sintered clunks quite successfully in several models but they are too big to use in SLEC tanks, unfortunately. 

[J D 8]

2 hours ago, J D 8 said:

     The only filter I use is in the model box tank. A large [ish] felt clunk which is commonly used in petrol motor mowers, brush cutters ect.  The small jets in these require fine filtering. Depending how much flying you do swap out every couple of years.

   Forgot to say I only fly glow or diesel.

[kevin b]

On 01/11/2022 at 20:21, Chris Walby said:

Oh no I have been doing it all wrong for the last 6 years with my non Laser engines! As I never do a nose up test on the Lasers I completely forgot to do it with my OS 2 strokes, strange I don't get many engine problems with them. 

 

Perhaps I need to fiddle with them more, but I prefer the turn up, tune and fly approach Jon advocates. Then again if I put the tank in the wrong position, forget to install the clunk and have a few leaks here and there I could make them unreliable.🤣

 

Not to mention putting them in the boot of the car after a days flight and then just taking them out next time you want to fly.

[Jeremy Scott-hake]

Just a few words about John's low oil fuel.

Earlier this year I bought a Laser 160 flat twin for a 1/4 scale cub project, I decided to remove the Laser 150 single from my Wot 4 XL and run the new twin to learn how to handle it.

At the same time I bought 2 gallons of the new low oil fuel on John's recommendation, having used nearly one and a half gallons over the last few months the air frame has little or no oil on it ! .

I was a bit unsure of the tuning high an low needles having read and followed the instructions it was a 5 minute task hot or cold the engine starts first time after priming, runs with out missing a beat .

I checked the tappets after the first gallon and no adjustments were required.

I can fly for 10 mins on 12 Oz selec tank mixed hooning around.

The engine is a champ I am really pleased with it and it's performance on the low oil fuel.

One or two electric flyers have noticed how fuss free it is, as they enjoy the usual shinanagans of nitro flyers twiddling about. 

Many thanks John for a super engine .

 

 

[Mike Mc]

I agree the FT-160 is an excellent running engine and easier to tune than I expected. I have more than 6 gallons through it. 

 

After a good bit of prop testing, I settled on an XOAR 18x6 PJD Laminated prop. Bottom prop in photo.

 

 

[Nigel R]

15 hours ago, Jeremy Scott-hake said:

I can fly for 10 mins on 12 Oz selec tank mixed hooning around.

 

That's really rather good for something that size.

[Jon H]

Thanks for the FT updates chaps. Do you have any videos of the beasts in action? If you do you could actually pop them in the Laser gallery thread as the various photos of Laser powered models live there so the videos might as well live there as well. 

 

The on the fuel consumption, the low oil fuel helps this as each cc of 'fuel' actually has more actual methanol fuel in it as there is less oil taking up space. As a result you lean off your needles to get back to the correct air/fuel mixture. 

[Artto Ilmanen]

Gents,

 

I need to replace the bearings of a Laser 150. I wonder how to do it? Some hints how to do it? The engine is from the year 2008-2010 if my memory serves me.

 

thanks,

 

Artto

[Artto Ilmanen]

Gents,

 

Some remarks on "top of the tank - middle of the carb" rule;

 

The instructions that came with my 300v (2013) say "..The tank should be as near the engine as possible and on the centreline of the carburettor." Not being a native speaker I misunderstood this means "middle of the tank - middle of the carb" 😔  See picture.

 

Hence, the tanks are now mounted in accordance with "middle of the tank - middle of the carb". I can't lower them further, no space physically available as the fuselage has a foam core.  I could try remounting the engine upright but then the space available enables the tanks to be mounted: "top of the tank is 1 inch lower than middle of the carb"

 

Anyways, i do not have any particular issues and it seems neither of the setup alternatives is optimal. Maybe i should just stick with the current setup? Or is there anything I could gain if I mounted the engine upright?

 

I'm happy with the engine but of course I want to follow the manufacturer instructions to get the most out of my engine in all circumstances. Hence the question.

 

thanks,

 

Artto

[Jon H]

Hi Artto, long time no see. 

 

Changing the bearings on the 150 should be pretty simple. Heat up the front housing in the normal way and tap them out. If you have a bench press this will make installing the new ones so much easier. Use 6001-2rs with rear seal removed for the front bearing and 6002 open race for the rear. If you have to change the pinion drive bearing as well be sure to mark all of the cams and take photos of their positions before you remove them. 

 

On the tank placement thing if the engine is running well then just leave it alone. As we have discussed for many years, if its working there is no reason to fiddle with it. Get one of those fidget spinner things instead if you have nervous fingers 😉 

 

I recommend the top of tank-centre of carb installation as it is guaranteed to work in any model, with any fuel, flown in any way. There is a little wiggle room in there depending on the model, but i cant write 500 sets of instructions to cover every possibility there is and detail all of the various if's and but's. Also why would you not want your installation to be perfect anyway? Its one less thing to worry about if its all by the numbers. I did start making an addition instruction sheet to detail tank placement but i never got around to finishing for some reason. I might have to look into it again. 

 

 

[Andy Stephenson]

Jon,

Is it possible to get the timing of a Laser engine 360° out, as a full cycle of a 4 stroke is 720°.

[Jon H]

7 minutes ago, Andy Stephenson said:

Jon,

Is it possible to get the timing of a Laser engine 360° out, as a full cycle of a 4 stroke is 720°.

 

No the geometry of the engine means its got a 270 degree firing interval and then a big gap before it fires again. A 360 inline would fire 360 degrees apart just as the smaller ones do provided i build it as a parallel twin, which i will. If i didnt it would be 180 degrees and then a gap like the FT series engines. 

[Artto Ilmanen]

1 hour ago, Jon - Laser Engines said:

Hi Artto, long time no see. 

 

Changing the bearings on the 150 should be pretty simple. Heat up the front housing in the normal way and tap them out. If you have a bench press this will make installing the new ones so much easier. Use 6001-2rs with rear seal removed for the front bearing and 6002 open race for the rear. If you have to change the pinion drive bearing as well be sure to mark all of the cams and take photos of their positions before you remove them. 

 

 

 

 

Thanks Jon!

 

I take Laser engines seriously - that's why I asked about the tank installation 🤗

 

bearing change: 

 

I do not have a bench press so I either can try heating the front housing in oven (like at 200° C for some time ?) or maybe I can find an engine workshop to help with installing the new ones.

 

Anyways,

 

-so I pull the drive flange out carefully by using normal puller? 

- when reinstalling the drive flange and taper collet: shall I check the gap between the front housing and drive flange? (is there any specs for this to measure)

-when demounting the front housing: does the engine need to be at TDC? (or does it matter at all)

 

Is there any hint or a recommended practice to check the pinion drive bearing condition with minimal dismantling?

 

 

[Jon H]

I have never used heat to get our bearings out as i have a press and a special tool here at work. I cant say exactly how hot you need to get it so some experimentation will be needed im afraid. 

 

The prop driver comes off with a puller as normal and there is nothing to check when you put it all back together. I recommend you try and put the parts back together the way they were. You will see a witness mark in the propdriver showing where the collet was so pop it all back exactly like that. 

 

I would set the engine to TDC of the compression stroke before taking it to bits as this can aid reassembly although to be honest i would just remove the whole top end of the engine as...

 

The pinion drive bearing can only be truly inspected by complete removal of all the cams. However if the pinion drive rotates smoothly when spun by hand with everything assembled, and there is no gritty feeling then it is probably ok. You will have to remove the head and cylinder barrel to check this though as the conrod will be in the way and the cams still under pressure from the pushrods.  

[Artto Ilmanen]

23 minutes ago, Jon - Laser Engines said:

I have never used heat to get our bearings out as i have a press and a special tool here at work. I cant say exactly how hot you need to get it so some experimentation will be needed im afraid. 

 

The prop driver comes off with a puller as normal and there is nothing to check when you put it all back together. I recommend you try and put the parts back together the way they were. You will see a witness mark in the propdriver showing where the collet was so pop it all back exactly like that. 

 

I would set the engine to TDC of the compression stroke before taking it to bits as this can aid reassembly although to be honest i would just remove the whole top end of the engine as...

 

The pinion drive bearing can only be truly inspected by complete removal of all the cams. However if the pinion drive rotates smoothly when spun by hand with everything assembled, and there is no gritty feeling then it is probably ok. You will have to remove the head and cylinder barrel to check this though as the conrod will be in the way and the cams still under pressure from the pushrods.  

 

Thanks Jon  this is all clear. It seems I'd better to remove the head and cylinder barrel to make it right - as you write to check the pinion drive bearing, too.

 

If my memory serves me, I do not need to change any gaskets upon reinstalling the cylinder barrel and head? Is this correct?

 

 

 

[Andy Stephenson]

1 hour ago, Jon - Laser Engines said:

 

No the geometry of the engine means its got a 270 degree firing interval and then a big gap before it fires again. A 360 inline would fire 360 degrees apart just as the smaller ones do provided i build it as a parallel twin, which i will. If i didnt it would be 180 degrees and then a gap like the FT series engines. 

Jon, I meant can you get a single cylinder Laser engine 360° out on the timing, I understand about the twin cylinder Vee engines and leave that to the experts as recommended.

[Jon H]

59 minutes ago, Artto Ilmanen said:

 

Thanks Jon  this is all clear. It seems I'd better to remove the head and cylinder barrel to make it right - as you write to check the pinion drive bearing, too.

 

If my memory serves me, I do not need to change any gaskets upon reinstalling the cylinder barrel and head? Is this correct?

 

 

 

 

Nope no gaskets, just a smear of silicone round the front housing before you assemble it. 

[Jon H]

4 minutes ago, Andy Stephenson said:

Jon, I meant can you get a single cylinder Laser engine 360° out on the timing

 

Um...im afraid you have lost me. I dont understand what it is you are asking

[Andy Stephenson]

28 minutes ago, Jon - Laser Engines said:

 

Um...im afraid you have lost me. I dont understand what it is you are asking

I'm not sure if I am either, I'll have a think if there is a different way of asking this question.

[Chris Walby]

Surly its timed correctly or not?

Either its timed as per the manufacturers recommendation and settings (correctly) or its wrong. Wrong can be any number of permutations apart from one... and that when its correct.   Simples

 

Now for other applications like race engines there are many settings depending on what you want to achieve, but that's off topic so off to the shed for me!

[Kim Taylor]

38 minutes ago, Chris Walby said:

Surly its timed correctly or not?

Either its timed as per the manufacturers recommendation and settings (correctly) or its wrong. Wrong can be any number of permutations apart from one... and that when its correct.   Simples

 

Now for other applications like race engines there are many settings depending on what you want to achieve, but that's off topic so off to the shed for me!

I think that the confusion may be that IF the motor had timed ignition, then it would be possible to get it 1 full turn out. With a glow plug, or 'wasted spark' (spark plug sparks every turn of the crank) then not so much!!

Kim