Engine Doctor

Providing you Xtra wot has been built true you shouldn't have any problems, they are a very sorted model. II built one a few years back with a YS 140 in it and it was superb. It was moved on to a club mate who fitted an old Enya 90 fs. He asked me to test it for him as he was worried about the power available. It flew perfectly ,not as fast and no vertical performance compared to the YS but still plenty of power.The CG as per instruction is fine so fit your tail weights and get correct CG. P's hope weather is helpful. Edited By Engine Doctor on 05/09/2015 09:19:00 Edited By Engine Doctor on 05/09/2015 09:21:07

Hi Gonzo . I don't have any problem with my set , it all works fine .Have you got you posts mixed up ?

? That's strange as both my FF9 's are fitted with the pre telemetry modules from early on and no problems ? Just lucky I guess .

You said the model is listed as a 50cc . It was probably designed with thrust lines to accommodate the extra weight of the 50 cc unit . In your case I would suggest a neutral thrust line and trim the model for level flight at the speed you want. Ballooning when powering off is a symptom of too much lift being generated by the wings for the flying speed . Is there any adjustment for wing angle /incidence ? Reducing incidence would be the most effective but if fixed then adjusting trim and thrust lines is the only way forward. Only make one adjustment at a time and test fly . That way you will be able to gradually get it to fly the way you like . Let us know what actions you take and results . Good luck.

Hi Eric . I use Fr-Sky modules and Rx's with my FF9 . I use all sorts of servos and never had a problem . The Fr-Sky link is brilliant . i have also converted a Futaba 6 EX and a Skysport 6 with Hack modules and never ha d a glitch . If your a lone 35 meg flyer then fine but if you have to watch out for other 35 megers then keep the Fr-sky and dump the dodgy servos for care free flying . E.D.

Hi did you checked the ring gap before fitting ? I never trust so called "pre gapped rings" as engines do differ slightly.If a gap is too small and the engine gets hot the ring expands and the ends touch then there is no room left for expansion so it starts to grip the cylinder and engine will stop abruptly. A rule of thumb for ring gaps is 5 thou gap per inch of bore diameter . To check it remove ring from piston and fit into cylinder at the tightest unworn part , suggest the very topabove the rings travel limit as the bore may be slightly tapered. If the the bore/cylinder is parallel then use the very bottom of the cyl. Use the piston to set it square before checking the gap. If it needs adjusting use a needle file . File little and check often to avoid a large gap that will leak badly. A classic example of too small ring gaps were the big SuperTiger engines that frequently cut out unless run in for hours. Gapping the ring sorted the problem and made the engines much more reliable. Letvus know the out come

Ah sorry for doubling up BEB you got in while I was typing .

Hi dont give up It shouldn't be a problem. Do you have a covering iron and hot air gun ? The hot air gun should be a Modelling type and not a DIY type will make covering the tips a lot easier than using a iron on its own DIY hot air guns can be used but be very careful as they area lot hotter and can burn through the covering and you fingers Start with the underside of the wing . Allow plenty of covering to get a good hold of , why ? this will become apparent later . Once you have tacked the straight edge across the wing pull the covering taught to the center of the wing tip and tack in place with your iron set to low now work out from there halving the distance each time until you have it tacked all the way round . Now turn your iron up to medium and tack down the straight edge firmly . Next you will need a covering hot air gun. Get a good hold of the excess covering and as you apply the heat pull around the tip towards the top of the wing . Do this little and often around the tip until you get the tip smooth without any crinkles . Any small crinkles in the corners can usually be shrunk out with the hot air gun. Now trim off the excess and iron down the surfaces firmly with iron set between medium and hot . When happy do the top of the wing the same . When both top and bottom are covered use the hot air gun to finish shrinking .A little practice with some scrap covering will help a lot . Ultracote should be quite easy to use . Solarfilm stretches well but if far less forgiving with heat .Good luck . Edited By Engine Doctor on 25/08/2015 16:21:10

Posted by Rob Tothill on 25/08/2015 08:44:41: ED I was interested in what you said about varnish build up, what is the cause of this? Is there a solution if it occurs? Hi Rob/ Area 51. The main cause of varnish build up is using a castor based fuel and the engine overheating.The Castor oil is vegetable based and cant withstand the heat that modern engines produce. Castor based fuel causes varnish especially when the engine gets hot . It sets like the castor oil skin on paint products . Synthetic based fuel prevents this and keeps an engines internals a lot cleaner. You may find some fuels that have a small percentage of castor oil added to the mix "to give added protection against a lean run " this can still cause gumming or varnish on internals and burnt on oil on the external casings and exhaust and eventual damage to the engine. Castor is fine on old diesel engines and similar that don't produce the power and subsequent heat that modern engine produce . Looking at the pic of the snapped con rod I would suspect that it has been run weak to get every last bit of power as they are not the most powerful of engines and the eventual build up of varnish has cased the piston to be grabbed / siezed by the rotating cylinder and bingo ..................snapped rod . It has obviously been run with a lean mixture and become very hot as the con rod should never get that discoloured with normal running. Only solution to varnish build up is to strip and clean the parts .I use cellulose thinners and a old tooth brush but be careful not to damage piston and liner .Best solution is to not let it build up in the first place . Many engines appear to  have been  run for years on castor fuel without problem but they are run by owners who obviously know how to set the engine a tad rich to prevent overheating . I now only use castor oil in my vintage diesels and cox engines everything else gets synthetic oil with no problems . JMO. I don't want any death threats from Castor oil enthusiasts Edited By Engine Doctor on 25/08/2015 11:51:29 Edited By Engine Doctor on 25/08/2015 11:53:54

Re fuel filters . I only use the sintered bronze metal clunk filters fitted in tanks and in my flight box so fuel is double filtered. They totally filter fuel without chances of air leaks and will draw last remnants of fuel from tank provided they lay in it . They also help prevent the ingress of bubbles from frothing fuel (caused by engine vibration) into the fuel line . If you MUST use a inline filter then make sure the mesh is made of stainless steel as the brass stuff will dissolve and bits of metal will clog the carb jets .

Don't wish to teach you to suck eggs but have you checked all other parts for damage or found the cause of the rod failure ? I would definitely check the cylinder for varnish build up that can cause the piston to grab and twist the conrod causing the failure. The colour of the rod suggest it's got very hot ? Fitting a new rod will only treat the symtom not the cause. Good luck Ps why not fit the other engine and save a tenner and have more power ?

Hi seal the exhaust with some epoxy . Strip and clean first then assemble with some 30 min epoxy .Job done . To diss-assemble just remove from engine and heat . I also use some one hour type Aaldite to seal the exhaust to the engine this works better than any gasket . make sure the screws are well oiled before assembly and again to strip just remove screws and give muffler a sharp tap and it comes off . Dont waste time with gaskets as they always crush and alow exhaust to come loose .

Hi too soon to tell if it helps prevent corrosion . Itdefinitely made for easier starting and smoother running on my garden VAC/ blower. Two planes filled with it also seemed to be easier to start. I have also dosed a gallon of glow fuel with it didn't affect the starting or running of the Saito 50 .

Posted by Braddock, VC on 29/11/2013 17:02:55 Petroil mixture, on the other hand, does not absorb water and actually acts as an insulator thus preserving the metals within the crankcase. It also helps that most 2 stroke oils are designed to be slightly alkaline which helps reduce the possibility of galvanic action. Hi our petrol is now laced with a good dose of ethanol and does absorb moisture from the atmosphere unlike the petrol of some years ago. I srtipped an petrol engine a few months ago and was surprised to see corrosion on the bearings ! I am currently trying fuel fit made by Briggs and Stratton to combat fuel corrosion in their engines. I also noticed that when using petrol to clean engine parts it goes milky due to the absorbed water unlike the older petro of years gone byl.

Yes it will be a shame but think about the manufacurer s point of view. If they can't sell enough then its just not worth their effort. One kit in 20 years doesn't really keep a company afloat . There are very few decent kits around today but DB still do a Se5 I believe . Edited By Engine Doctor on 20/08/2015 09:11:23

Posted by Stevo on 18/08/2015 16:54:50: Loads of advice on here so ask away. Also whereabouts are you? - I'm sure there's a mentor waiting in the wings Blimey Stevo what size model do you think he's making !

Position engine and hold firmly in place. Heat a lenght of piano wire to red and push into mou t through the engine mounting hole. The hole left is a perfect start for your drill.

A couple of modelers I know would still complain if you gave them a gold plated super quiet silencer for free . They would probably complain at the cost of the screws to mount it or a scrap of tube to connect it ! . I am truly amazed at the lengths some modelers will go to to save a quid . Sorry off subject.

Posted by Foxfan on 17/08/2015 11:05:36: Interesting...many model boats with fast brushless power are every bit as noisy as I/C engined models, yet most ponds now say "no IC". Perhaps some light cross bracing in the fuselage which holds the sides a little tighter would help with little or no weight penalty? MrTin Hi Foxfan I think that IC boats may be banned due to the oil discharged. Castoroil used to break down but synthetics ATC just float on the water and polute the pond.

One post mentioned the"air frame ,construction" as part of the problem that is so often overlooked. I have over the last few days spent quite a lot of time sorting a 84 inch Taylor craft fitted with a 26cc engine and a JE Pitts type silencer. Engine was spinning a 17 x 10 wooden prop that is well balanced. It was making 90 plus dB at full throttle measured at 7 metres! I fitted two exhaust pepperpot outlets upped the prop to a 18 x 10 and noise came down to 81/82 dB. So plane was flown . In the air it sounded like a flying drum ! The culprit ,.......... You guessed it was the air frame resonating. Retested it on the ground and if a helper placed their hands on the fuselage sides the noise went down to 79/80 db .The engine prop are as smooth as would be expected without any undue vibration. That problem cant be sorted very easily so model is grounded for the moment .A lot of the very lightly constructed models especially the 3d types suffer from this unless you can fit a silky smooth power source. I even heard a electric model at our field last week that was noisier than the I/C planes flying at the same time .Cause was the out of balance prop. Re noise look at the whole model not just the silencer and keep our flying sites.

I have to agree. But blanket bans are a lazy effort by committees to sort the problem. If the problem is tackled before the complaints start coming in then something can usually be done about it. In the past I have argued with one or two stubborn individuals that they must quieten their models, they were glow. It boiled down to them not wanting to spend some cash for different props. They were eventually told to sort it of fly somewhere else. They did sort it very quickly once they knew the club were serious. Engine suppliers are also to blame in part as they are selling engines with silencers not fit for purpose. They don't seem to realise that eventually they won't be selling any engines if clubs or councils ban them. So let's start a poll that means something ! Who would buy a engine with an effective silencer Etc. Makes more sense than asking about connecting battery chargers to computers !

Hello Roy . Just Engines call their add-on silencer plug a pepper pot outlet. You can see one fitted to a silencer in their NGH engine adverts. If you know anyone wi5h a lathe they are dead easy to make . other manufactures make them for most popular petrol engines.

The supplied silencers are not fit for purpose and only serve to point the exhaust and noise away from the model. You would think that by now petrol engine suppliers would have got to grips with this as its in their interest.The Stinger by JE mentioned earlier do work to a point. I have made my own version with quite good results .A decent Krumschied silencer from Stuart McKay models will silence the exhaust effectively and together with a higher pitch prop should get you nearer the mark . What prop are you using? The manuals tend to give generic running in sizes ,I have found that most petrol engines are capable of turning much higher pitched prop at lower revs than glow engines . The stingers usually drop the max rpm by a couple of hundred but upping the props pitch more than make up for it . Good luck and letus know how you get on.

Posted by Bob Cotsford on 13/08/2015 16:19:18: How about least favourite? Mine would be the Frog 80 diesel, I wore grooves in my finger trying to start that POS. Frog 50 could be the same ! or was it us and a lack of technique ? I have read that some of the early Frogs were not the easiest to start but others were really easy . My friend cant start a diesel to save his life and gets really annoyed when me or another mate get it started in a couple of flicks . I did recently have a go at a frog 50 for a friend and couldn't get a pop out of it . I gave up on that one and suggested a dart or ED baby instead . I remember walking quite a distance to Russ models in Battersea Rise SW London because my Merlin wouldn't start only to see them put it in a test stand and start it in a couple of flicks . Its our turn now to show the young -uns how its done . But they have to show me how to program the phone , tablet, telly etc etc.

120 members and no other users that I am aware of . Although they may just be using an alias that I don't know of .