By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Laser Engines - Technical questions

All Topics | Latest Posts

Search for:  in Thread Title in  
Jon - Laser Engines22/05/2020 23:01:07
5422 forum posts
263 photos

I have used menz wood props without issue. all of my engines over a 180 use wood props.

David Davis23/05/2020 13:56:59
avatar
3687 forum posts
693 photos

Hi Jon,

I have two Laser engines currently installed in models, an old 150V in a WOT 4 XL and a 70 in a Big Guff vintage model which is close to completion. I am currently running the V twin on a fuel supplied by Southern Modelcraft which consists of 75% methanol,10% nitro and 15% oil, of which the oil content is made up 13% synthetic 2% castor which I bought to suit my Japanese and Taiwanese four strokes.

I also have stocks of Southern Modelcraft straight fuel, 85% methanol and 15% oil, again, 13% synthetic 2% castor. I can buy both methanol and nitro from my club. I see that you are recommending the use of 7.5% oil in Laser engines.

If I were to turn up with 5 litres of straight at my club's workshop and bung it into a large clean bucket and add 5 litres of methanol, by my maths I would then have 10 litres of straight fuel with a 7.5% oil content. If I were to add 0.5 litres of nitro I would acheive your favoured Laser fuel mix.

So two questions:

  1. Would you recommend this fuel for the old 150V?
  2. Would the 70 be alright with this fuel? I have run up the engine on the test stand with the 10% nitro mix.

 

 

 

Edited By David Davis on 23/05/2020 13:58:42

Jon - Laser Engines23/05/2020 15:16:12
5422 forum posts
263 photos

On the 150v i would stick to 15% oil. Synthetic is fine but 15% is probably a good idea as they were not built to the same standard or with the same materials as later engines.

On new Lasers 5 nitro and 10 oil is totally fine and we are working on lower oil still

I wouldnt use more than 5 nitro, you just dont need it and it really increases fuel consumption

Ace24/05/2020 09:08:02
311 forum posts
18 photos

Similar question regarding a Laser 100 with the single bolt valve cover and silver TT? carb. Is it ok to use the same fuel as in my new Lasers - S/Modelcraft 10% fully synthetic, 5% nitro? ( I don't mind some risk if its marginal and accept its not a company recommendation and just an informed opinion )

Jon - Laser Engines24/05/2020 09:48:10
5422 forum posts
263 photos

all engines built after 1992 have hardened cranks and should be quite happy with the low oil. Exceptions to this would be corrosion on the crank pin or some other issue but in general it should be fine

Engine Doctor24/05/2020 11:17:53
avatar
2469 forum posts
39 photos

Dave when you have used your existing fuel replace it with the fully synthetic. Even 2% castor makes a mess and cokes parts up . Southern model craft fuel is good honest fuel and Dave will tel you exactly whats in it . Used SMC fuel for years and never had a problem .

Ace24/05/2020 11:33:06
311 forum posts
18 photos

As ED have used it for years and now use S/Modelcraft 5l 10% nitro Hi -Lube (20% fully synthetic) + 5l Methanol = 10l, 10% oil, 5% nitro in my Lasers. I then use std 10 % Hi Lube in all other 2/4 s.

Rocker29/05/2020 09:17:32
348 forum posts

Hi I have a Laser 80 and it is not running right. It OK at full throttle but erratic at mid range .I retune the slow running needle valve like Jon show in he's video ,it is a bit better but just can not get it to run right in the mid range .I then look at the valve clearances and the inlet valve was fine but the exhaust valve had no clearance what's so ever .I have now adjusted the valve clearance on both valve to so the 0.004 feeler gauge goes through and the 0.10 does not .Due to our club field still being closed ( tell me about it ) I can not check it in flight .It seems to run fine on the ground .Would the exhaust valve having no clearance make much difference to the mid range running of the engine or am I just hoping it did ?

ken anderson.29/05/2020 09:26:09
avatar
8637 forum posts
779 photos

hello rocker,Jon is the man...but I think you may have found and solved the problem your self.....if the exhaust valve had no clearance imagine when it was hot it wouldn't be able to function correct(close/seal)….see what the main man says.

ken anderson...ne..1...…. E/V dept.

Jon - Laser Engines29/05/2020 09:55:52
5422 forum posts
263 photos

Hi Rocker

The basics:

What fuel, prop, plug and top end RPM?

Valve clearance can have an impact but usually its small unless they are massively wide. My quick and dirty method of setting valves is to tighten until no clearance and they slacken the screw about 1/8 turn. Its not perfect but works well enough if you are in the field or dont have all the tools to hand. frankly, its accurate enough for our purposes anyway so dont loose too much sleep over a thou or 2 of valve clearance.

bert baker29/05/2020 10:41:17
avatar
1586 forum posts
326 photos

Get a new carb,,

might be unmetered air getting in

Rocker29/05/2020 10:52:13
348 forum posts

Hi Jon,

I have the Laser 80 in a Seagull Fokker C1 ,which is basically a Bowers Flybaby in disguise. The exhaust valve had no clearance what so ever but the inlet was fine .I have now adjusted the valves to 0.004 .I am using Model Tec Laser fuel and I have a 14x7 prop on it . Has I said I have adjusted the slow running needle valve like you showed in the video and it was a lot better but still ran a bit erratic at mid range .Then I discover the exhaust valve had no clearance it was tight up against the rocker so I adjusted it to 0.004 .It seems better but I have not try it in flight yet .Would the tight exhaust valve be the cause of it running a bi erratic at mid range ?

Rocker29/05/2020 10:52:17
348 forum posts

Hi Jon,

I have the Laser 80 in a Seagull Fokker C1 ,which is basically a Bowers Flybaby in disguise. The exhaust valve had no clearance what so ever but the inlet was fine .I have now adjusted the valves to 0.004 .I am using Model Tec Laser fuel and I have a 14x7 prop on it . Has I said I have adjusted the slow running needle valve like you showed in the video and it was a lot better but still ran a bit erratic at mid range .Then I discover the exhaust valve had no clearance it was tight up against the rocker so I adjusted it to 0.004 .It seems better but I have not try it in flight yet .Would the tight exhaust valve be the cause of it running a bit erratic at mid range ?

Edited By Rocker on 29/05/2020 10:53:14

Jon - Laser Engines29/05/2020 11:47:39
5422 forum posts
263 photos
Posted by bert baker on 29/05/2020 10:41:17:

Get a new carb,,

might be unmetered air getting in

Nothing personal but i always see this advice and totally disagree with it. In 25 years i have only ever had to replace 2 carbs. 1 due to crash damage and 1 that was worn out so just replacing the carb as a first port of call is a little premature. Its also not very cost effective as 90% of erratic running problems come down to either poor fuel, poor plug, or bad tuning. While its true air leaks can cause problems its rare that an entire carb need to be replaced in order to fix it.

Rocker, the valve clearance is not critical so i doubt it is the cause of the problem. My suspicions are still plug/tuning.

When you say you set the engine up according to my video, how far did you go leaning off the slow run? In my experience most chicken out early so its possible you have a little more leaning to do.

If in doubt, shoot a video (without the camera in the prop wash!) and upload it you youtube as an unlisted video. You can then post the link here and we can have a listen

cymaz29/05/2020 11:57:38
avatar
9197 forum posts
1186 photos

If I have any run issues with a glow the first thing is to toss the old plug and put on a new one.

Edited By cymaz on 29/05/2020 11:57:58

tigerman29/05/2020 13:06:16
218 forum posts
1 photos

Hi Jon ,

Tried to down load the video but failed .It would not download into my album so I could not post it .It was only a few seconds long .Do not know what went wrong

cymaz29/05/2020 13:11:30
avatar
9197 forum posts
1186 photos

Load it onto youtube then use the YouTube icon above in the icon / menu bar.

P.S. you will need a yt account if you haven’t got one already..

Edited By cymaz on 29/05/2020 13:12:29

bert baker29/05/2020 21:17:21
avatar
1586 forum posts
326 photos

Be quicker to pop the engine in the post

Jon had his fingers on my 180 last year

was quick turn around and very pleased 😀

tigerman02/06/2020 15:25:25
218 forum posts
1 photos

Hi Jon I did what you surgested about leaning the slow running needle more and BINGO .the Laser 80 runs has sweet has a nut again At low rev middle range and at full chat .Thanks

Rocker02/06/2020 18:54:44
348 forum posts

Just a quick qustion .Will the Laser 180 fly the Seagull Hurricane 2083 mm ?

All Topics | Latest Posts

Please login to post a reply.

Latest Forum Posts
Support Our Partners
Slec
CML
electricwingman 2017
Sussex Model Centre
Advertise With Us
Sarik
Latest "For Sale" Ads
Has home isolation prompted you to start trad' building?
Q: The effects of Coronavirus

 Yes - for the first time
 Yes - but Ive bashed balsa before
 No - Ive existing projects on the bench
 No - Im strictly an ARTF person

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E!