Bob Cotsford Posted May 20, 2014 Share Posted May 20, 2014 So I've mounted a Laser 160V V twin on the front of a BlackHorse Macchi 200. To get the exhaust out of the rear of the radial cowl I've added right angle extenders to the Laser exhausts, then Just Engines Quiet extenders on the end to reach the rear of the cowl. Because of the length of the cowl and shape of the fuselage the front of the tanks is about 6cm behind the carbs and the top of the tanks about level with the carbs. The fuel supply is via twin clunk lines. I've fitted OS F plugs and a 16*8 APC prop, the instructions indicate I should get 8-9000 rpm. Starting up at idle was ok, and I followed the running in instructions - 30 secs at 3000 then a minute or so at 5000 rpm. The problem is that 5000 rpm is nearly flat out (max 5300) and adjusting the needles doesn't make a fat lot of difference. As soon as I lift the nose by about 10 or 15 degrees the engine cuts no matter how far out I wind the needles. I suspect I may have two separate problems: 1) the exhaust extensions are too restrictive or a bad length creating destructive harmonics preventing the engine breathing freely. 2) the tank is a bit far back as well as being low. With 1) it's just not able to draw the fuel. 1) I'm addressing by ordering some 11mm bore ali tube to make big bore extensions for the exhausts, 2) I'm think will need a couple of Perry oscillating pumps. Any thoughts? Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 20, 2014 Share Posted May 20, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 20, 2014 Share Posted May 20, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 20, 2014 Author Share Posted May 20, 2014 Andrew, it's got the supplied 'silencers' fitted, the rest is just to extend them out of the cowl. Certainly the next step is to try without the extensions for a comparison. Brian, you may be right but I notice the Perry blurb now states that they are not recommended for opposed twins. It used to just say twins. I live in hope. Even though it's not even started running in I'd hope to get around 8k rpm full bore. These days I think it's Jon who answers emails to Laser, rather than Neil. Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 20, 2014 Share Posted May 20, 2014 If laser still do it get the bendy pipes with the adaptor that extend the exhaust significantly. You probably won't need to fit the supplied mufflers as the volume and resistance of the pipes will slow the gas down so they won't be any noisier than the standard setup imho. Lasers are comparable to dysons in that they will suck up fuel from way down so the height shouldn't be a problem. Few more things,percy nailed it with the extended running in and the other thing baffle the front of the cowl so that air is directed over the cylinders. Ensure the tank vents are pointing directly into the prop wash without bends etc. Lastly ensure the carbs are getting fresh, cool air, if they are using heated air from inside the cowl then the engine efficiency will drop markedly. I used those silicon exhaust diverters tie wrapped to the carb at one end the other outside the cowl. Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 20, 2014 Share Posted May 20, 2014 Sorry, ps to the above, a few years back one of the mags had an article by ken shephard re fitting a laser with a petrol engine carb, the ilet frob the tank was retained and a discharge pipe fitted into the top of the carb. A nipple was fitted to connect to the gas side normally fed by the crancase on a two stroke and this was connected to the crankcase breather on the engine. Positive fuel delivery without the cost of a perry pump. I have one setup on my OS 160 but yet to run though it pumps fine connected to the exhaust pressure nipple on a 91 Fx. Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 21, 2014 Share Posted May 21, 2014 Bob, I know it sounds really daft but are you sure both cylinders were firing and that the throttle was open fully? Your tank position sounds pretty good to be honest as 6cm is not far, unless its significantly lower than the engine I doubt its a problem. One other thing that sounds stupid but is very easy to do, did you plug off the filling pipe and accidentally plug the tank breather in the process? if so there would be a vacuum in the tank and that's never going to work! My suggestion would be to put the engine back to factory spec regarding the exhausts and work from there. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 21, 2014 Author Share Posted May 21, 2014 Jon, it is a possibility that it was running on one as I've not heard it running before, if so it has a beautifully smooth tickover and pickup as a single! I never thought to compare head temperatures. I did check both plugs after running it and maybe they weren't as bright as I'd have liked so I'm not excluding the possibility it was on one. My power panel was showing around 6 or 7 amps but who knows how accurate that is and I do know OS Fs take a lot of current. Throttle fully open - yes Vent blocked - definite No. There are a few options to try this weekend starting with no exhaust extensions and a beefier glow supply. Once it revs correctly I can move on from there with routing the exhaust. Edited By Bob Cotsford on 21/05/2014 09:52:14 Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 21, 2014 Share Posted May 21, 2014 Posted by Braddock, VC on 20/05/2014 17:20:47: Sorry, ps to the above, a few years back one of the mags had an article by ken shephard re fitting a laser with a petrol engine carb, the ilet frob the tank was retained and a discharge pipe fitted into the top of the carb. A nipple was fitted to connect to the gas side normally fed by the crancase on a two stroke and this was connected to the crankcase breather on the engine. Positive fuel delivery without the cost of a perry pump. I have one setup on my OS 160 but yet to run though it pumps fine connected to the exhaust pressure nipple on a 91 Fx. Sorry, I didn't make clear that thepetrol carb was used solely as a pump to supply fuel to the makers carb on the laser. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 21, 2014 Author Share Posted May 21, 2014 I assumed as much BVC, iirc the pump is connected to a T fitting on the breather in these setups. Being a V twin the pump output would then have to supply the carbs via another T fitting. I think someone tried this on a 300V but had trouble balancing the feed between the carbs, it might have been on the RCMF site that I saw it. Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 21, 2014 Share Posted May 21, 2014 Its unlikely that one power panel will be man enough for both plugs. I use a glow stick for each cylinder on my twins and they go very nicely. A T piece in the fuel line wont work as I tried it and one carb tries to rob fuel from the other as its easier to do that that draw it from the tank Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 21, 2014 Share Posted May 21, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 21, 2014 Author Share Posted May 21, 2014 this engine had better run really, really well after all this! Why didn't I just go electric from the start? Now I need to drill dirty great big holes in the cowl to use glow sticks - I see a pair of on-board glows in this things future! Edited By Bob Cotsford on 21/05/2014 16:41:14 Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 21, 2014 Share Posted May 21, 2014 On board glows are a waste of time and not recommended by Laser as they are the cause of so much unreliability. not to mention the weight. For testing just remove the cowling and in the long term some remote glow points could be added somewhere out of the way. I have these installed on my 300v and it works very well. Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 21, 2014 Share Posted May 21, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted May 21, 2014 Share Posted May 21, 2014 Hi Bob, you don,t say if it is new Laser you fitted, I was with a friend at a show,and Mr Laser himself, said regarding A new Laser engine (single cylinder) needed over 3 hours running in at least. Cheers Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 21, 2014 Author Share Posted May 21, 2014 it's a brand new V twin. Most of the problems are because it's going in a big radial cowl so it's totally enclosed except for the tips of the needles, and I'm trying to avoid drilling more holes for plug access and the like. Also we have a rather draconian noise limit hence I'm trying to funnel the exhaust outlets to where they will be masked during testing. Well, regardless of Laser's recommendations it's getting a South Herts dual glow driver as they work well on my other enclosed engines and it saves trying to power two plugs from an external source for starting via a hidden connector with the associated wiring resistance. The weight of an on-board system really is minimal, little more than the sub-C Ni or 1S LiPo cell used for power. I've not found the ones I've used to be unreliable in any way. Ps - the cowl is off and I was using a remote connector. The problem I have with the remote connector is that the power output from the panel seems marginal for two plugs. If I'm going to use a separate 4AHr glow battery then it might as well live inside the model, functional ballast. If need be I can always switch it off after starting. PPS - FB3 - it may well need 3 or more hours to fully run in, but it really should be able to reach close to peak revs. Laser's running in instructions call for 30 secs at 3k, 1 minute at 5k then tune at full throttle. Roll on the weekend for further experimenting. Edited By Bob Cotsford on 21/05/2014 23:32:20 Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 22, 2014 Share Posted May 22, 2014 the south herts glow drivers are not too bad actually as they are the sensing type. Just make sure you switch it off when you set up the slow run needles or it will mess up the setting. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted May 22, 2014 Share Posted May 22, 2014 Bob, while others are commenting on the exhausts, you note that winding the needles right out doesn't make any difference and the engine cuts as you raise the nose, which all points to lean running due to insufficient fuel supply. If it was the exhausts then they would cause the engine to stop in a nose up test or make the needles ineffective. I found with my two lasers that they would actually run lean and it was important to set them up with a tacho to get the best performance (but we are only talking 100's rpm difference not 1000's), I also found with my Vega twin that again using a tacho was important to fine tune both needles. Where have you got the vent pointing, if it's just straight out or backwards then the prop airflow will cause a low pressure in the tank, I secure the vent on my lasers to point towards the prop. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 22, 2014 Author Share Posted May 22, 2014 Posted by Frank Skilbeck on 22/05/2014 08:31:52: Bob, while others are commenting on the exhausts, you note that winding the needles right out doesn't make any difference and the engine cuts as you raise the nose, which all points to lean running due to insufficient fuel supply. If it was the exhausts then they would cause the engine to stop in a nose up test or make the needles ineffective. Sorry Frank, this confused me - are you saying that you think it's inadequate fuel supply or the restricted exhaust? For myself, if it were any other brand of engine I would straight away have blamed the tank position but it seems everyone has faith in the Laser's ability to draw fuel with far from ideal tank locations. Obviously when I set up the exhausts I didn't think it would be very restrictive as I've maintained the silencer outlet size through to the exit out of the cowl. The weather forecast isn't good for garden testing this weekend, the neighbours may have to put up with me testing it in the garage Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 22, 2014 Share Posted May 22, 2014 Frank, he is 4000 rpm down on what he should be getting so at this point there is something more fundamentally wrong. Putting the engine back to factory stock and making sure both cylinders are lit is a good start. From what I can see of the exhausts I do not think they will pose a problem but its worth checking. also the Laser twins are easy to peak without a tacho, I never use one on mine but a lot depends on your specific set up. If in doubt about the needle settings then laser have base settings on their website, but as the engine was test run before it left the factory it is likely to be an installation issue somewhere. Personally I think it was only running on one cylinder, I cant think of another way to loose that many rpm! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 22, 2014 Share Posted May 22, 2014 Bob how are you feeding fuel to the engine? Do you have twin pick ups in the tank or are you feeding off one via a Tee piece? If the latter I wonder if its unable to flow enough fuel ro supply the engine.... Are the holes in the clunk(s) clear? I had one a while back that hadn't been drilled through completely....Oh yes it took me a while to find that one out!!! You often get the hole partially blocked with swarf or plating debris too.... Just a thought....... To avoid using twin glow starts how about wiring the plugs in series back to one remote connection & use a 4V supply... Quote Link to comment Share on other sites More sharing options...
flight1 Posted May 22, 2014 Share Posted May 22, 2014 Hi heres my two pens worth.. 1. You have not mentioned if you have two tanks feeding the carbs or one tank with two seperate clunks fitted?(it wond't go well if you got one clunk off a y join) 2. Are both idle screws tured out the same( I find the needle settings out the box from factury are right and only need a tweek when run in a bit). 3. you are 3000 rpm down sounds like you only running on one cylinder the xhausts set up you'v got are restrictive but not to this extent.( if only one cylider running the xhaust gas one one will be a lot hotter and a simple check with yu finger). 4. Check both barrels in carbs are operating symetrical so when at idle both barrels have the same opening. and check the valve clearances 0.5 mm to 1mm (gap will get bigger as it warms). 5. for starting use one remote glow plug for each cylinder. you can start with one and then swap the glow driver over to get the other going. ( noticed in picture one remote plug lead is frayed culd be shorting so not enough juice to plug0 Hope this helps. one you got this teathing problem out the way you will be happy me thinks Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 22, 2014 Author Share Posted May 22, 2014 Plugs in series with 4v supply Steve? Short of splitting a LiPo pack I don't have a 4v supply, and it would be another item of kit required just for one model - I'll bear it in mind but I'll try the on-board glows first. Flight: 1) It's got a twin clunk tank, I actually pumped fuel into the tank and drained it again through each feed - been caught out before connecting the feed tube to a tank vent. Both sides filled and emptied at a fair old rate. 2) Idle screws were as they came from the factory - I did open them both by 1/8 turn each but the idle was nice and smooth and pickup was pretty good except after extended idling, hence opening by 1/8th turn. 3) That will be the first thing I'll check next time 4) Both barrels opening equally - checked before installation - valve clearances 1/2 to 1mm? Mistype I think! Doesn't sound rattly but that's another item to check. I assume it should be the usual 0.05-0.1 mm, 2-4 thou? 5) Good idea - it's only a fabric shroud that's frayed, the lead is silicon covered wire and not shorting but full power direct from the panel to each plug in turn should make sure both burners are on. It will be interesting to see how it compares starting and running deliberately on one cylinder. Quote Link to comment Share on other sites More sharing options...
flight1 Posted May 22, 2014 Share Posted May 22, 2014 oops a bit of typo with the valve clearances, I shall better check my typing and spelling better next time Quote Link to comment Share on other sites More sharing options...
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