Laser Engines - Technical questions

[Paul De Tourtoulon]

Yes, thanks Jon, I have an APC 14 x 6 trimmed on take off,😆

a New Apc 14 x 6 and 14.5 x 6 and a 15 x 6

Graupner 13.5 x 8

Master 15 x 8

And a few that I could steal from other planes hanging up in the Garage, I have got muddled up with the numbers so

tomorrow after today's holiday I will start again from scratch and inform the neighbors of my trials with the Laser 4 stroke symphony😇,,,

[Jon H]

Just for info i tested a used laser 100 just now and saw 9300 from an APC 14x7. 

[Paul De Tourtoulon]

Thanks, Jon, I fitted a Novarossi 9mm carb and an APC 14 x 6 gave me  9300 and Graupner black pro 13 x 7  11000 rpm,

I need a Graupner 14 x 6 to really compare,,,

 

Having lots of fun,

 

 Ps I don't know the English term, but I did run some 1000 wet and dry with some oil down the cylinder to clean it up and hope that it helps to make the old piston ring bed in better, it must have because there is a lot more compression on it now.

 

 

Edited May 10, 2023 by Paul De Tourtoulon
ps

[J D 8]

           The word you are looking for is "Hone" never done a model engine myself but have done several full size car and Land Rover engines. The light scratches help new rings bed in [ may help your old one some] and also retain a thin layer of oil on the bore. Cheers, John.

[Paul De Tourtoulon]

1 hour ago, J D 8 said:

           The word you are looking for is "Hone" never done a model engine myself but have done several full size car and Land Rover engines. The light scratches help new rings bed in [ may help your old one some] and also retain a thin layer of oil on the bore. Cheers, John.

Hone, the magic word that I forgot living in France for 45 years, and it does work on the std steel Laser liner, It went up to 9.500 rpm an hour ago then settled between 9.300/9.400rpm, it does that when throttling up from idle for a few seconds.

 

 

[Scott Edwards 2]

Not a technical question, but a reminder to all Laser fans ! Friday June 2nd, BMFA Buckminster, Laser 40th Anniversary Fly In !

 

 

[Steve Dunne]

I was looking forward to the fly-in, and swapping notes on Laser engines, but sadly due to health problems I won't be able to make it.

Have a great day, everyone!

Steve.

[Andy J]

Jon, was the extension air/fuel mixture intake tube fitted to ST carbs on older style Laser engines a standard item supplied by ST, or did you machine up a suitable tube?

 

The reason I ask is that I would like to purchase a replacement carb body but the ones I have seen don't have the extension.

 

Probably the next question is how was the extension tube secured to the carb body as it appears to be an interference fit.

[Jon H]

The ST carb stub was made by us and it was a pressed fit. Those ST carbs were discontinued by us in 1995 and by ST themselves by the early 2000's i think. You will be very hard pressed to find a spare these days. 

 

Which engine is it from? 

[Andy J]

Believe my engine to be a Laser 70 or possibly a 75 but cant be sure.

 

Found this item but I am guessing if it is the correct body

[Paul De Tourtoulon]

I have been fiddling with carbs on my Laser .90, any carb will work ( for me ) as long as it can be fitted to the pipe, or just make another pipe,,,

[Jon H]

20 minutes ago, Andy J said:

Believe my engine to be a Laser 70 or possibly a 75 but cant be sure.

 

Found this item but I am guessing if it is the correct body

 

pop up a photo of the engine. At least i can id it for you

[Andy J]

As requested Jon. Really need to know what ST carb this engine used and if the carb body spare  I posted earlier is indeed correct.

 

 

[Jon H]

thats a pre 1986 75 and you dont stand a chance of getting a new carb body as they were discontinued in 86. The one you linked looks like its for a 60 2 stroke and will be a good 50% larger than the dinky one we used. Im afraid i havent a clue which one it was as i was only 1 year old at that time! 

 

What is wrong with the current body? it looks alright. 

[Andy J]

Well it was just a thought to replace the carb body as one of the screws that holds the spray bar has sheared off so have secured it in place with epoxy.

 

Did find this carb body on ebay which possibly is for a 60 engine.

[Jon H]

9 hours ago, Jon - Laser Engines said:

The one you linked looks like its for a 60 2 stroke and will be a good 50% larger than the dinky one we used

 

[Robert Cracknell]

Seems to be plenty of Irvine carbs of differing sizes on Fleabay.....can one if these not be used?

[Engine Doctor]

Any decent carb will work on laser providing its of similar bore to the original. I had a carb ftom an old sc 120 fs and it was a loose fit on a 75 inlet stub . Cleaned and abraded lightly then glued it on with Araldite standard it ran superbly and at idle for about 10 min sucked every last drop of fuel from rest tank .

[Jon H]

As ED points out any carb should work as long as its got the right bore. I would shoot for 7.5-8mm for a 75

[Engine Doctor]

On 28/04/2023 at 17:39, Artto Ilmanen said:

Ok, thanks for Jon's kind help I was able to dismantle my both 150s for bearing change. I first tried to remove the prop driver with a 2-claw puller: the result was tears in the eyes as the only thing I was able to achieve was to get some (yet small, fortunately) marks on the prop driver -> so next attempt was to press the crank with a quality press which did the job without any further hassle. I also pressed the pinion drives out with a press. Then I applied some heat to get the pinion drive bearings out - tjios helped and teh bearings came out very easily with just a tine help of a screwdriver and a very slight knock. 

 

Now the next phase will be to remove both front and rear bearings of the front housing. Jon must have some black magic trick to do the job easily but I plan to test to heat the front housing at 200°C and I hope this will help removing the bearings as aluminium is expected to expand more than the steel bearings.

 

Let's see how things proceed.

 

As I side note, on one of the crankcases there are fairly symmetrical marks (not quite, though) around the pinion drive bearing pocket? I wonder if they are a result of earlier bearing change or alternatively they could be some minor marks that came during the casting process?

 

 

@Jon - Laser Engines I believe you said the other day Loctite 638 is the recommended adhesive to secure the pinion drive bearing? (small amount of it is recommended on the bearing pocket)  You also said one could use Loctite 595 for the same job? The latter is more attractive as any future bearing change will be much easier with it as the Loctite 638 is a strong adhesive.

 

So could I skip the Loctite 638 and go for the 595 or did I miss something?

 

 

 

 

LOCTITE Bearing Fit will hold a bearing if it loose in its housing . Staking a bearing is a bodge really but before things like loctite were invented it was a common practice . A proper cure would be to machine for a larger o/d bearing but its just not worth the bother. Bearing Fit is really strong so beware and make sure you only use enough and that none gets into the bearing races. And yes it can be heated to release for bearing changes in future.

Edited June 15, 2023 by Engine Doctor

[Rocker]

My trusty Wots Wot XL suffered a faulty radio switch today and is no more .This leaves me with a Laser 180 but looking the ARTF avaliable today that would be suit my Laser 180 are a bit thin. So I am at a lose has to what to get for my trusty Laser 180 .There does not seem much about .I quite like the Seagull Stuka but that is for a 50 cc motor .There are a lot if models for a 120 4 Strokes  but then it seems to jump to 50cc motors .Might just have to put the Laser 180 in the draw for the time being 

[Paul De Tourtoulon]

Rip, wot's wot, I lost my Mirage 2000 the same way 3 weeks ago, you can't seem to get the good quality Futaba switches any more just cheap rubbish.

 As for the Seagull Stuka, I am sure that your 180 would pull it around the sky nicely, here is one with a petrol 40, probably around the same power output of your Laser, I have the ESM one ( 2.05m ) that was probably put together by a plasterer but my not so powerful Saito  FG-30 is more than enough.

 

 

Edited June 16, 2023 by Paul De Tourtoulon
2.05

[Jon H]

13 hours ago, Rocker said:

My trusty Wots Wot XL suffered a faulty radio switch today and is no more .This leaves me with a Laser 180 but looking the ARTF avaliable today that would be suit my Laser 180 are a bit thin. So I am at a lose has to what to get for my trusty Laser 180 .There does not seem much about .I quite like the Seagull Stuka but that is for a 50 cc motor .There are a lot if models for a 120 4 Strokes  but then it seems to jump to 50cc motors .Might just have to put the Laser 180 in the draw for the time being 

 

How hard did it hit the deck? With the ground baked hard at the moment any frontal impact will seriously shock load the front bearing. it should really be replaced and the crankshaft checked for straightness. 

 

On the Stuka front, i think the 180 would be fine. I mean, its a stuka. Just enough power to haul its fat self up to enough altitude to then fall down hill and drop a bomb before going home (or not). It will not be especially sprightly with a 180 but it should do all the things a Stuka should do.  

[Manish Chandrayan]

Is this the copy from SA or original Laser. Never have seen that box and hence the query. The AGC sales sticker on the box does look genuine

Edited July 1, 2023 by Manish Chandrayan

[Andy Stephenson]

When Neil made them, he used to send them out in plywood boxes. This is how my 75 arrived in 1986. It's definitely an early model possibly a 90 with the original customer's initials punched into the mounting. There were reports of Laser copies but I don't think they had the cheek put "Laser" on them. It looks new and un-run, nice find.