Laser Engines - Technical questions

[Steve Dunne]

I bought 4 a couple of years ago. The first three did not last long, and did not seem to help on starting.

I disposed of the fourth and returned ot OS-F plugs, which work very well for me in Lasers, OS 4strokes and Saito 4strokes.

 

Steve.

[thebluemax]

Thanks Jon and Steve for getting back to me.  I have OS-F and YS #4 plugs on hand and usually use those. The YS #4 plugs are supposed made by OS and the same as the OS-F plugs. I found these Super Cats in my spares box and don't know anything about them.  Since they are made in the UK I thought you guys would know for sure.

Thanks again and stay safe.

Bill 

[Engine Doctor]

Re F problems and complicated starting procedure with YS engines and prop throwing. I Run a few YS engines , great bits of kit , and never had one throw a prop . If the correct starting procedure that YS recomend is used they start quickly and reliably.

Over the years I like many I have had the odd engine throw a prop.

 . One from a OS clone type Magnum 120 put a large dent in my caravan ! That was proven to be incorrect valve timing from an new out of the box engine. Once valve timing was reset it was no problem . Many things can cause a prop to throw, from not being tightened enough or the prop hub crushing and loosening the nut  to incorrect glow plug , dodgy fuel or even bad plumbing installation to fuel setting /tuning and having glow plug switched on while reving the engine.

 

Another issue is engines that have been messed with. I have in the past been asked to look at engines that their owners have had problems with . "It's never been tampered with" I'm often told then once I get into it it's obviously been taken apart and the head shim is missing ! This will often turn a nice running engine into a monster and can severely damage the engine or its operator as the timing is dangerously advanced.

 

The few Lasers I have owned have never been an issue and have had good handling characteristics . I believe this is attributable to the timing set up that Lasers use . They are tuned to run reliably and not tuned to within an inch of their lives to squeeze that last rev. Also every engine is hand built by a person who knows what they are doing ; whereas high production engines like ASP etc are bound to have the odd problem engines.

 

A question for John. Have you ever tried to provoke a Laser to throw a prop ? If so the results would be interesting to those tha seem to have the problem more frequently.

 

[Jon H]

24 minutes ago, Engine Doctor said:

 

 

A question for John. Have you ever tried to provoke a Laser to throw a prop ? If so the results would be interesting to those tha seem to have the problem more frequently.

 

 

Never tried deliberately, but i did accidentally manage it on a 75 once. The carb was a super tigre and the slow runner had been set so lean that it made the main needle ineffective. So i wound the engine up to full power, noted it was lean, and opened the main needle...imagine my surprise when nothing happened. in the time it took for me to unwind the main needle in search of richer mix (so far it nearly fell out) the engine over heated and kicked the prop off. I nailed it back on, fixed the slow run needle, and then it was good as gold. Even so, i have lean cut plenty of our engines over the years while faffing about and none of them have ever thrown a prop so this was an oddball. 

 

The only prop spitting engine i have recently had dealings with was an enya 53 fs. It was a nightmare until i fixed the carb. It originally had a 5mm choke airbleed carb...which was useless, so i bought the enya 53 twin needle carb. This has a choke of 7.2mm if memory serves and it completely ruined the engine. It went very fast at full power, but once you let it cool down and re started it the prop was off before you got past half throttle unless you opened the main needle, warmed it up, got to full power, then leaned off again. Nightmare. So, 5 minutes on the lathe had a 7.2mm O/D x 5mm I/D sleeve made up. Pressed it into the carb barrel, drilled a hole for the slow run needle and put it all back together. Much better, no more chasing props. ? 

[Engine Doctor]

Hello John . I still have an Enya 60 4C I bought years ago . It would throw props all the time . I tried different plugs, washer under the plug to reduce Comp ratio etc . It could be tuned to run full throttle and was fine until you shut the throttle and it would immediately throw it with a loud bang. Similarly tuned for slow running or idle it would idle for long periods and as soon as you opened the throttle it again throw the prop with a loud bang . When I stripped it down to investigate I found the head gasket / shim was missing . Obviously this had cause advanced timing and pre ignition  hence the prop throwing .The pre-ignition had also bent the gudgeon pin and damaged the piston . I re-built it with new piston and gudgeon pin , bearings etc and a new head shim cut from  annealed litho plate  . Its now the easiest starting and great running engine with a reliable  idle.

[David Davis]

I am in the process of rebuilding the fuselage of my Big Guff vintage model to replace the one which was burnt in a LiPo fire. I will be using a Laser 70 in it. I have reached the stage of planning the tank and radio installation. I would like flights of 10-15 minutes with this model.

 

Like most traditional aeromodellers, I have a good selelection of serviceable fuel tanks!

 

What size fuel tank would you recommend in this installation?

 

 

[Frank Skilbeck]

I think my Majestic Major has a 6 oz tank and on it's Laser 62 easily does 18 mins.

[Nigel R]

whatever you have lying around, 6oz - 10oz... you don't have to fill the bigger tank all the way up

 

 

[Jon H]

I use 8oz on the 70's in my twin. I get 10 minutes of mostly flat out running as its a sport model and i tend to thrash it!

 

Model like yours, you could fit a gallon bucket as you have all the space, the weight wont matter, and you dont have to use it all. Just come down when you feel its time for refreshments. 

[Rocker]

Can anyone tell me if the Laser 80 will fly the Seagull Grasshopper OK 

[Jon H]

50 minutes ago, Rocker said:

Can anyone tell me if the Laser 80 will fly the Seagull Grasshopper OK 

 

 

This one?

 

http://seagullmodels.com/gas-power-scale/l-4-grasshopper-90-inches-371.html

 

If so yes. I flew a customers 92 inch black horse cub using a 100 and it was effortless at half throttle or less. Another friend had a 150 in a similar cub and it was over powered for sure. 

 

Mount the engine on its side, fit a 15x6 prop (perhaps 16x5 if you can find one) and run with it. The model will not be over powered but its a Cub, they fly with their wings, not their propellers! 

[Rocker]

Thanks  Jon  Can anyone tell me if the Laser 80 will fly the Seagull Grasshopper OK 

[Rocker]

19 minutes ago, Rocker said:

Thanks  Jon  Can anyone tell me if the Laser 80 will fly the Seagull Grasshopper OK 

Thanks Jon

[thebluemax]

Hi Jon,

I have a Laser 160V that needs a home in a plane.  I can't find any specs on the 160V so I was wondering if it would be a good match for the H9 Ultra Stick 30cc?  I am not looking to do 3D with it but some aerobatics would be nice.  I do have a 300V twin but I am putting that in a Platt FW-190.

thanks,

Bill

 

Hangar 9 Ultra Stick 30cc ARF, 81" | Horizon Hobby

[Jon H]

it would be fine in there. Mount it upright for fuel tank placement though, andyou may need to make  little tank bulge in the top of the fuselage to get the tank exactly in the right spot ? 

[thebluemax]

That great!!!  Thanks Jon.

Bill

 

I was thinking about trying one of these or maybe need 2 on the firewall to feed the carbs.  Supposedly it constantly holds 1/4 of an ounce of fuel.

QuikFire - Fuel Balancer and Filter - JL Power Products (jlproducts.net)

FlyingRC.net - QuickFire Fuel Balancer and Filter

https://youtu.be/1FreGdLMTUc

 

 

 

Edited April 17, 2021 by thebluemax

[J D 8]

              Interesting but says for petrol engines only in the instructions.

[thebluemax]

You can use it for glow too.  I used it on an OS-91FX and it worked fine.   It says it on the package for glow and gas.  

Edited April 17, 2021 by thebluemax
added picture

[Jon H]

Never tried one but im not a fan. Its just another thing to go wrong and if the tank placement is correct, which should be easy enough, its not going to serve much of a purpose anyway. 

 

The problem is over the years we have seen all kinds of things added to fuel systems and they never work reliably. One person might have no trouble, another will have nothing but. For this reason we just recommend getting the tank in the right place as this is always guaranteed to give the best result. 

 

Its also free ? 

[Gary Manuel]

12 hours ago, Jon - Laser Engines said:

it would be fine in there. Mount it upright for fuel tank placement though, andyou may need to make  little tank bulge in the top of the fuselage to get the tank exactly in the right spot ? 

Hi Jon.

 

Are Laser engines really that sensitive to tank placement that the fuselage of ARTFs need to modified to add a "bulge" for the tank and also to mount the engine upright rather than sideways as intended? 

 

Is this a unique problem associated with Laser engines or do other engines have the same issues?

 

Personally I've never had problems sticking a Saito 150 into this type of model without modification.

[Andy May 2]

Would someone be good enough to post a side-on view diagram  ( or post a link to one that already exists ) of the ideal height relationship between the Laser carb and the fuel tank. ?  There are many written descriptions and photos of installations. The photos and videos all suffer from a degree of parallax error and the written sometimes vary in the landmarks used as reference points.

 

This would help this easily confused brain of mine.  Thanks heaps

Edited April 18, 2021 by Andy May 2

[thebluemax]

5 hours ago, Jon - Laser Engines said:

Never tried one but im not a fan. Its just another thing to go wrong and if the tank placement is correct, which should be easy enough, its not going to serve much of a purpose anyway. 

 

The problem is over the years we have seen all kinds of things added to fuel systems and they never work reliably. One person might have no trouble, another will have nothing but. For this reason we just recommend getting the tank in the right place as this is always guaranteed to give the best result. 

 

Its also free ? 

Roger that.  I have always gone with Jon's advice and never had an issue.  Just thought I would ask if this was a good possible solution to a low tank==> carb issue.

[Ron Gray]

9 hours ago, Gary Manuel said:

 

Personally I've never had problems sticking a Saito 150 into this type of model without modification.

Is that because the Saito spray bar is a lot closer to the engine C/L?

[Jon H]

9 hours ago, Gary Manuel said:

Hi Jon.

 

Are Laser engines really that sensitive to tank placement that the fuselage of ARTFs need to modified to add a "bulge" for the tank and also to mount the engine upright rather than sideways as intended? 

 

Is this a unique problem associated with Laser engines or do other engines have the same issues?

 

Personally I've never had problems sticking a Saito 150 into this type of model without modification.

 

side mounted would be fine if it were a single, but the question was about a 160v twin and they only mount upright or inverted. a inverted is a non starter its upright all the way. It might be possible to get the tank right without mods, but equally, it might need mods so i mentioned it. 

[Jon H]

6 hours ago, Andy May 2 said:

Would someone be good enough to post a side-on view diagram  ( or post a link to one that already exists ) of the ideal height relationship between the Laser carb and the fuel tank. ?  There are many written descriptions and photos of installations. The photos and videos all suffer from a degree of parallax error and the written sometimes vary in the landmarks used as reference points.

 

This would help this easily confused brain of mine.  Thanks heaps

 

 

Top of the tank in line with centre of carb. Its really that simple. There is wiggle room around that figure, but the amount of wiggle room depends on the model being flown and i cant give 20 different recommendations so i give what always works. Top of tank, middle of carb. 

 

Edit, you also minimise fuel head change with this setup as all of the fuel is always below the carb and this helps tuning stability. 

Edited April 18, 2021 by Jon - Laser Engines