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Laser Engines - Technical questions


Jon - Laser Engines

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Well, as usual I have found the opposite. My 70 in the Tiggy was a devil to get fuel to the carb from cold until I put it on silencer pressure so that I could block off the exhaust with my finger to force some fuel through, despite an inverted motor and a high tank. When draining after a session I try to draw the fuel back from the carb.

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52 minutes ago, Martin McIntosh said:

Well, as usual I have found the opposite. My 70 in the Tiggy was a devil to get fuel to the carb from cold until I put it on silencer pressure so that I could block off the exhaust with my finger to force some fuel through, despite an inverted motor and a high tank. When draining after a session I try to draw the fuel back from the carb.

 

 

High tank makes the problem worse in many cases. You need to tune the slow run needle very lean due to the gravity assist on the fuel when running and and to stop it dripping fuel when not running. 

 

As this setting is well beyond the operating range of the needle problems are the predictable result. As already mentioned it is likely the carb would draw fuel but not enough to fire the engine when cold. 

 

If the tank was where it was supposed to be the needle would be set within its operating range and it would work much better. 

 

  

 

 

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21 hours ago, Chris Walby said:

 

 

Artto,

 

Would be worth checking to see if the valve clearance is correct before adjusting? 

Rotate crank until piston is at top dead center on the firing/power stroke (both rockers should have some slack/clearance. Check valve clearance and adjust if necessary. I would be quite surprised if they actually needed adjusting in normal operation unless the engine has been in use for many hours.

 

Hi Chris,

 

Thank you - I certainly will check the valve clearance first. It may be just fine and no adjustment is needed. I think I have adjusted the valve clearance once or twice on my 300v. Once after running-in and maybe another time at some point.

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The old 150v that I bought (£50) was stripped down and I could see very little signs of wear on the internals and the bearings felt fine. I redid the timing after chatting to Jon, set the needles to 6 open (low) and 1 1/5 (high) and had the first opportunity to try it out today. The first effort saw it running on one cylinder so I replaced both plugs just to be on the safe side and this video was the second attempt. I did not touch the needles during the test runs.

 

 

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  • 2 weeks later...

150 single cylinder engines are fine and can still be serviced. However, the 150 has been in production since 1992 so the chances of finding an engine that is beyond economical repair is moderately high.  

 

When looking at a 2nd hand engine of ours, especially if bought remotely on ebay or something, assume immediately that it needs a service. That is £100 quid right away. Then consider the possibility it needs a carb and exhaust and that is another £80. Factor in postage and the cost of a new engine and you should not be paying more than £150 for a 2nd hand laser 150 bought without being able to inspect it first. Cover yourself as best you can against the worst case scenario. 

 

The other thing to consider is that our engines are always incorrectly identified so you might not actually be buying a 150. I have seen 80's sold as 150's before, 100's as 120's, and 180's as 150's. This is partly due to them having no size marked on them, a practice i stopped as it was just daft to not have the size on it. That said they all look completely different to me and the photos on the website should help with i/d so i dont quite know how so many folks get it wrong. In any case send me a photo of the engine before you buy as i can identify it and give you an idea of its age. 

 

Hope that helps. 

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42 minutes ago, Phil B said:

Thanks Jon Can you identify it from these or I can take more. 

 

Laser 150. Manufactured 1998 and its carb replaced after 2006. Prop nut seems to have been replaced by an OS locknut missing its locking part. Seems to be missing its carb and exhaust retaining clamps as well but these are cheap and easy to replace. Its got a newer exhaust that it would have shipped with as well. 

 

Looks pretty decent from the outside but its no spring chicken so a service would probably help it out. 

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50 minutes ago, Jon - Laser Engines said:

 

Laser 150. Manufactured 1998 and its carb replaced after 2006. Prop nut seems to have been replaced by an OS locknut missing its locking part. Seems to be missing its carb and exhaust retaining clamps as well but these are cheap and easy to replace. Its got a newer exhaust that it would have shipped with as well. 

 

Looks pretty decent from the outside but its no spring chicken so a service would probably help it out. 

I have all those parts but removed them when I cleaned it. What would you say its resale value would be? 

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I am not really in a position to value individual engines as i cannot recommend a price on something completely unknown to me as i have no idea of its condition. It might not have a piston in it for all i know and yes, i have seen that before. My involvement in any way could/would be interpreted as some sort of guarantee and i would be implicated then if something went wrong or the seller decided to mug some poor punter as i have seen on countless occasions in the past. Honestly some people must have no moral compass at all. 

 

2nd hand sales are between the seller and the buyer so do not involve me or company. 

 

I can offer general buying advice as i did earlier to try and steer people away from buying a nail, but i cannot value or promote 2nd hand items for sale. Providing information on the engine, its support status and so on is the only assistance i can offer. 

 

 

 

 

 

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IMHO, fly it yes, suit it possibly not.

 

If you can build it light and it doesn't mean thrashing the 70 just to keep it airborne + you fly scale it should be ok

 

How about build it for an 80 (bulkhead, bearers etc) and put a 70 in, then try a few different pops and all should be okay. If however it becomes a ground squirrel then its minor mods to get the 80 in. The other thing is the 70 is a bit lighter than the 80 which helps if you are intending on floating about enjoying he sound of a Laser.

 

I have a 62ish in a Ripmax Nova 40 trainer and its as aerobatic as I can ring it out, but looks and sounds best at 1/4 throttle on the buddy lead 😃 

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15 hours ago, David Davis said:

Will a Laser 70 fly a DB Sport & Scale Auster?

 

Yes, provided you are happy with scale performance. 

 

We normally recommend the 80, but in truth i am sure the 70 would be ok. I fly a 72'' Piper Tomahawk of nearly 7lbs using an enya 53 4 stroke and its well over powered for scale with half throttle being more than adequate once in the air. The auster is a bit bigger and a bit heavier so the 70 should do ok. At the end of the day, it will fly with its wings and not its propeller so power only really effects rate of climb and maximum speed. Neither of those things are a big concern in an Auster! 

 

Chris's idea of building with the 80 in mind but fitting the 70 is sound. That way an upgrade can be made if you need it. 

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1 hour ago, Chris Walby said:

IMHO, fly it yes, suit it possibly not.

 

If you can build it light and it doesn't mean thrashing the 70 just to keep it airborne + you fly scale it should be ok

 

How about build it for an 80 (bulkhead, bearers etc) and put a 70 in, then try a few different pops and all should be okay. If however it becomes a ground squirrel then its minor mods to get the 80 in. The other thing is the 70 is a bit lighter than the 80 which helps if you are intending on floating about enjoying he sound of a Laser.

 

I have a 62ish in a Ripmax Nova 40 trainer and its as aerobatic as I can ring it out, but looks and sounds best at 1/4 throttle on the buddy lead 😃 

 

Thank you Chris.

 

I was given my Auster substantially built and covered in white Solartex. All I need to do is to install the radio and engine, make up some struts, paint the cowl, fit the cabin glazing and cover the underside, but you know how it is, other projects, like Bristol Blenheims and Mystics get in the way!

 

My problem is that I only have one Laser 80 but three Laser 70s.  One of the 70s is in the Acrowot and another is in the Big Guff soon to be replaced by my famous 62. That leaves me with two unemployed 70s. Everybody tells me to fit an 80 to the Warbirds Replica Hurricane which I intend to build over the winter, hence my enquiry about fitting a 70 to the Auster. Having said that I have an old but sound Laser 90 and a Thunder Tiger 91FS skulling about doing nothing.

 

I could fit one of those to the Auster.

Auster 1.JPG

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I’d go with the 70 as Jon has confirmed it should be adequate for scale performance. Do you want anything more with an Auster?  
 

Pottering around at scale speed is what this sort of model is all about - at that size it should look great on flypasts, touch and goes etc. and the Laser will sound great and should give good reliability. 

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On 07/08/2021 at 22:49, Jon - Laser Engines said:

 

 

For starting i use a 2.4v battery (a 2v lead acid would probably do) and i put the +ve lead on one plug, and the -ve lead on the other plug so they run in series using the engine to complete the circuit. I do the same with the 4 plugs on my OS Pegasus with them wired 2 in series 2 in parallel. I then run these wires to points on a cowl or similar where two croc leads can grab them.

 

 

 

 

 

Hi Jon,

 

I mounted my 300v back on my Yak 54

 

As I started the engine I had issues originated to poor condition 2v battery. It just failed to deliver more than about 1v when connected. I do think the battery is just done and need to replaced. My setup is: I'm using a remote glow adapter, the -ve lead on one of the nuts securing a silencer and the +ve leads to both plugs. I wonder if there are some benefit of connecting the leads as you do vs. my setup?

 

Another thing, I'm tempted to use a 2,4v NIMH battery to have a bit more power but is there issues reducing glow plug life time (OS F)  due to over voltage?  I'f my memory serves, the glow plugs are designed for 1,5v?

 

I suppose you do not use the 2,4v battery with your single cylinder engines / OS F plugs?

 

 

Edited by Artto Ilmanen
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