Laser Engines - Technical questions

[Artto Ilmanen]

11 minutes ago, Martin Harris - Moderator said:

Has a previous owner suffered from a loose bearing?  It looks like someone has attempted to stake the bearing with a centre punch and I rather doubt that was done at the factory!

who knows what a previous owner had done?

 

This is why I seldom buy any second hand engines. You never know that kind of ”maintenance” the engine has suffered from. These 2 come from friends who left the hobby.  Fortunately the marks do not cause any issues.

[Jon H]

I got my loctite numbers muddled up. 595 is the crankcase sealant, 693 (i think? the green one) is for holding the bearing in. Which you will need as that bearing fit is questionable given those punch marks. 

[Artto Ilmanen]

8 hours ago, Jon - Laser Engines said:

I got my loctite numbers muddled up. 595 is the crankcase sealant, 693 (i think? the green one) is for holding the bearing in. Which you will need as that bearing fit is questionable given those punch marks. 

 

Thanks Jon, this clarifies things. 

Funny thing is, basically most if not  all Loctite stuff to hold bearings in place are green.

 

Anyways, I suppose any retaining compound that holds the bearing in is fine as long as it withstands oil & fuel and works up to 150 degree celsius or so. 

 

I can’t find any Loctite 693 but instead a Loctite 603 might be the stuff you are referring to:

 

https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_6030.html

 

https://cdn-e.soneparcanada.io/PIM_Docs/Docs/STEP_ASSETS_PDF/71628609.pdf

[J D 8]

  The Locktite Stud and Bearing I use on the farm is red, so perhaps do not go on just the colour. Can't read container number as worn off.

[Ron Gray]

Loctite 648 is the high temp retaining compound, 638 the high strength stuff and 603 the general purpose medium strength.

 

I can vouch for the strength of the 638 and would advise against its use here!

Edited April 29, 2023 by Ron Gray

[Artto Ilmanen]

4 minutes ago, Ron Gray said:

Loctite 648 is the high temp retaining compound, 638 the high strength stuff and 603 the general purpose medium strength.

 

Thanks Ron,

 

The link above (selection chart) suggest the 638 for “loose fitting parts” while the 2 other are for “close fitting parts”. But I suppose any of these could work. 

[Jon H]

I will check the number on the bottle when i get back to work on tuesday. Right now, im off flying

[Artto Ilmanen]

10 hours ago, Jon - Laser Engines said:

I got my loctite numbers muddled up. 595 is the crankcase sealant, 693 (i think? the green one) is for holding the bearing in. Which you will need as that bearing fit is questionable given those punch marks. 

 

Fortunately the bearing pocket is intact despite what ever happened. So I assume I should be good with just correct retaining compound and right tools & working method (bench press and support from below to avoid any risk of deforming the crankcase) 

[Ron Gray]

38 minutes ago, Artto Ilmanen said:

suggest the 638 for “loose fitting parts”

@Artto IlmanenI used to use it when I had to make sleeves for fitting bearings after they had rotated and worn their mating surfaces. The sleeves were fixed using 638 then machined out for the bearings, the sleeves never moved!

[Ron Gray]

3 minutes ago, Artto Ilmanen said:

(bench press and support from below to avoid any risk of deforming the crankcase) 

Or warm crankcase and freeze bearings!

[Paul De Tourtoulon]

Digging around, this is all I can find for my .90 nothing on the Laser site, or anywhere else, is it correct ?.

 

Set valve clearance .002" - .004"      .05 - .1 mm. 

[Don Fry]

11 minutes ago, Paul De Tourtoulon said:

Digging around, this is all I can find for my .90 nothing on the Laser site, or anywhere else, is it correct ?.

 

Set valve clearance .002" - .004"      .05 - .1 mm. 

That’s good, new or old, or another way, tighten to just closed, back off 1/8 turn.

[Paul De Tourtoulon]

Thanks Don, I have done it the same as my OS engines, bearings are out,  6001  ( 12 x 28 x 8 )and 6002 15 x 32 x 9 )but the O rings are in a state, inside diameter 8mm outside 11mm but 2 mm wide, so I will order 8 x 10 x 2,,,

 

 A shame nothing on the Laser site,,,

Edited April 29, 2023 by Paul De Tourtoulon

[Artto Ilmanen]

3 hours ago, Ron Gray said:

Or warm crankcase and freeze bearings!

 True! But if a frozen bearing and a heated crankcase, say 100 degree celcius: can you add the retaining compound if warm / cold parts? At least you don’t want to have a crazy hot crankcase to avoid burning your finger upon putting the glue on the bearing pocket..

[Ron Gray]

To be fair, I would only use heat and freeze if it is a tight fit and if it is then you won’t need bearing compound!

[Don Fry]

3 hours ago, Paul De Tourtoulon said:

Thanks Don, I have done it the same as my OS engines, bearings are out,  6001  ( 12 x 28 x 8 )and 6002 15 x 32 x 9 )but the O rings are in a state, inside diameter 8mm outside 11mm but 2 mm wide, so I will order 8 x 10 x 2,,,

 

 A shame nothing on the Laser site,,,

Warning, those rings are imperial. 

[Paul De Tourtoulon]

I have a 7 x 11 x 2mm one, and it does the job thanks,,,

 

 I Just ordered a couple more 7x 11 x 2, 8 x 12 x 2 and the bearings,,,

Edited April 29, 2023 by Paul De Tourtoulon

[Artto Ilmanen]

2 hours ago, Ron Gray said:

To be fair, I would only use heat and freeze if it is a tight fit and if it is then you won’t need bearing compound!

well, ”orders are orders” 🤗. Jon recommended the retaining compond so who am I to know better?

 

It os a tight fit, though. You can’t push the bearing in with fingers

Edited April 29, 2023 by Artto Ilmanen

[Ron Gray]

Fair enough.

[Artto Ilmanen]

5 minutes ago, Ron Gray said:

Fair enough.

😆👍

[Simon Bulk]

Hi Jon,

 

I am the proud owner of a Laser 200V, mounted in a Seagull YAK 11. The engine runs perfectly and swings a Graupner G-Sonic 18x10 at around 7800-8000 rpm if memory serves. Plenty of power and torque at 6,5kg TOW!

 

The Graupner G-Sonic airscrews are a bit on the low load's end in regards of their stated size, so for example in a direct comparison a 18x10 APC is definetely a heavier load. Nonetheless it harmonizes very well. See here.

 

Before that I had a OS GT33 mounted in that airframe and I had my doubts whether the 4-stroke Laser 200Vee can keep up with the OS at same displacement. And, suprisingly, yes! It did very well. The OS GT33 swings the same prop maybe 300-400rpm higher, but that does not really matter because it's definetely a question of sound and emotions...

 

Nevertheless, I got an unemployed Laser 240V is my hangar and it matches with the engine mounts of the 200V. The extra weight would not be any issue. Is there any significant gain I can expect by replacing the 200V by the 240V? I mean the YAK 11 is a racer and it my expectation is that it might harmonize even better with the 240V?

 

Best regards & thanks in advance.

Simon

 

 

[Jon H]

I have a g sonic 18x10 on my 240 at the moment. I cant for the life of me remember the revs though, but i know they were good, around 8500 i think. It has sufficient power for the 80 inch 20lb La7 fighter in my profile pic so i think it might be excessive for the Yak. I flew the La7 last weekend to wish it a happy 13th birthday and even though i have flown it with bigger engines before, it was not short of grunt. 

[Simon Bulk]

Ok Jon, thanks for the prompt reply. 

 

One additional question to the prior topic of engine gaskets / sealings: As far as I know you use loctite / silicone for all engines (at least mine are all sealed with liquid silicone).

 

Is there any particular reason to do so? I would have expected cutted paper, silicone, OILIT, teflon or whatever fuel and heat resistant gaskets.

 

Best regards

Simon

[Jon H]

Not exactly sure why they started using it, i was a baby at the time! I suspect it was due to the simplicity given the very low volume production at the time. Its also cheaper than a paper gasket, easier to replace in the field, and its perfectly adequate at sealing up the engine. As production ramped i guess there was no reason to change it as it did the job. 

[Paul De Tourtoulon]

My old second hand bargain .90 is now in bits I am still cleaning it, I thought a picture is worth a 1.000 words, a funny looking piston, and no hole in the bottom of the con-rod for lubrication, I am tempted to drill a 1.5mm hole on one side of it ( yes the way it turns )what do you think Jon ?.

Edited May 4, 2023 by Paul De Tourtoulon
Forgot the photo,,,