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Member postings for Engine Doctor

Here is a list of all the postings Engine Doctor has made in our forums. Click on a thread name to jump to the thread.

Thread: Evolution .60 2 stroke help
20/06/2010 11:10:10
Hello Gazza . Air bubbles can also be caused by air being sucked in through the needle valve . Remedy is to fit a new "o" ring. Faults in the fuel pipes in the tank will only become evident when the fuel level get down to about half a tank and the pipes inside the tank are exposed to air. Does youre engine run ok with a completely full tank? If so it is more than likely to be the pipes leaking air.   Provided the fuel lines and pipes are OK check the following .Bubbles in the fuel can also be caused by vibration . This causes the fuel to foam = bubbles = air = weak fuel mix= dead stick. Have you  checked  the prop/ spinner for balance ? If thats ok , Is your tank mounted in foam ? Foam around tank should be firm enough to hold tank in place but soft enough to absorb the majority of vibration ; so reducing fuel foaming . Some fuels include an anti foaming agent . If you cant find out weather or not your fuel contains this then A small spray/few drops  of silicone furniture  polish or silicone dash boards treatment added to your fuel will stop foaming . You may be unlucky and have an unbalanced engine . I have seen these crop up over the years and theres not a lot you can do about that . Hope this pints you to the fault .
Thread: OS FT-120 Gemini twin
19/06/2010 16:25:42
Hello Dave .  Just a note of warning .My Gemini 120 MK1 twin was sechond hand and had been stored for some time  after being run on Castor fuel. The seller assured me it had been oiled up etc before storage . The castor had set like Varnish in the big end oilways and caused them to fail after a couple of minutes running.  Fortunately it didnt damage the crank shaft . The really annoying thing is that Conrods are unavailable for these engines and are totally different from the MK2 engine .t Mr Haytree helped me to rebuild with a couple of  good seconhand rods taken from a breaker he had. If your engine has been run recently then it will probably be ok . If it feel s stiff and gummed up then either strip and check it or fill the case with solvent that will disolve any castor varnish   and oil thoroughly before running . The oil ways are two tiny holes through the walls of the big end and block easily .  I imagine that parts for these engines ( apart from things like NV assemblies common to other models )are now extremely rare . Good luck with it .
ps . conrods made good key ring fob
Thread: RCV 90 SP dismantling
19/06/2010 16:06:41
Hello Mr Tall . I pretty sureits just a collet type prop driver but if you want to confirm then Give weston UK a ring on 01795-522020 . They are the UK distributor now and will be able to give you any info .
Thread: Bad experience with CRRC Pro 45cc
19/06/2010 11:18:26
Hi all . I am wondering if any other readers have had a similar experience with any CRRC pro petrol engines . I have had a CRRC 45cc for some years now . It was bought new at Watford swapmeet and  has always performed very well until recently when after a long flight it refused to start for another sortie. On closer examination the crank shaft had developed a lot of end float . I stripped the engine down and found that the bearings had started to float and rotate  in the crank case . This produced  aluminium patricles that found their way to the piston ring and decided to pick up on the chrome cylinder walls . Bits of chrome then found their way into bearings etc . I have a couple of these engines and this ,being an early model is the only one to show sloppy fits from new. After a thorough strip and clean ( you'd be amazed at the ammount of metalic particles that wash out of an engine) I decide to rebuild it . New bearings from a local bearing supplier where fitted using  Loctite bearing fit . This should hold them firmly in situ and a  steel shim was made up to reduce the end float on the crank to an accepltable level . Falcon Aviation supplied a new cylinder and piston rings (priced very reasonably and delivered very quickly ) .Once assembled it now runs superbly and is much quiter mecanically . I have run it for about half an hour so far on a 25- 1 mix fuel to get  running in started and it feels very smooth compared to it feel from new . I know these are budget chinese engines but beware of the early examples as the machining was obviously very hit and miss . 

Edited By Engine Doctor on 19/06/2010 11:23:00

Thread: help with petrol engine problem please
19/05/2010 10:12:49
Hello Paul . sounds like your add on silencer was causing too much back pressure .  You haven't removed the return spring on the butterfly arm have you? I know a lot of flyers that unhook it as they think its too strong for the servo. If you do this WILL allow the butterfly bearings  to chatter and wear quickly ,this allows air to get through and only remedy is a new carb. I run a DL 50 ( forrunner of DLE55) and its quite happy on 40 to 1 mix and will shortly be going to 50 to 1 . Its had a few hour running now. If you find that the standard muffler is too noisy as I did on the 50cc  then give me a e-mail and I'll show how I modded mine with vrtually no loss in performance to reduce the noise.
Thread: What colour is it?
19/05/2010 09:48:09
Hello David . Iv'e been using Southern Modelcraft fuel for years and as said earlier it changes colour from a dark pink to a dark brown ,as said , just like tea . Apparently it a reaction to UV rays. It doesnt harm it at all and will be fine to use . This colour change happens with various fuels that use Synthetic oil.Pro-synth used to start off a light blue and quickly went a almost black if left in the sun . I think a new dye is used now that is resistant to clou change  Castor will stay a straw colour . Use and enjoy .
Thread: How do you balance a spinner?
22/04/2010 11:14:17
Hello Ian I balance all spinners especially Ali spnners . I use a home made balance consisting of a hard balsa frame with two uprights approx 6 inches high and about 6 inches apart . These have powerful magnets mounted facing each other mounted near the top ( these are available at various model meetings or on the web) The spindle is a piece of 8 gauge piano wire ground to a point at each end . These points need to be pretty central or the shaft itself will be out of balance. This is approx 3mm shorter than the gap between the magnets. The prop or spinner is held on the shaft by tapered tufnol/ nylon sliders . these need to be a tight fit on the shaft. ( you could use a lenght of 4mm studding and make tapered nuts to hold prop etc) Mount the spinner on the shaft and mark the front and backof the spinner  so they always fit together in the same position. Now mout the shaft between the magnets. One end will touch a magnet and the other will float in the air . Let the spiner or prop settle and mark the low spot . You can the either grind alloy off the inside of the spinner or Using a large drill , drill indentations on the back plate removing alloy until yo get a balance . Take small amounts off as you can overdo it and end up with a backplte full of holes . You wont get it exactly right but will improve the balance considerably.
It really makes a world of difference . Hope it helps.
Thread: Fuel tank position too high
20/04/2010 15:12:58
Hello Roberto You could  try fitting a fuel pump / regulator . these work with pressure from the crankase and will only allow fuel through when engine is spun or started. Weston UK in Teynham England sell them under their own bran but there must be other suppliers who can help . Another benefit is that the fuel tank can be moved ont the Cof G so no change in flight characteristics with changing fuel load .
Good Luck
Thread: New CRRC 26cc 2 stroke petrol
15/04/2010 10:37:50
Hello Bruce I see you bought the CRRC engine . I still havent run mine yet but have been flying with a club mate who has a version 1 . This pulls his foker triplane around like theres no tomorrow . . It took a bit of sorting ,mainly electricaland fine tuning the carb , but is now fine and seems to get better and better. My 45cc CRRC was a bit of a so and so to hand start at first but is now a doddle . It seems it has to be primed correctly . To wet and it WILL bite. Not enough and you can flick all day without a pop. What I did find was that when running in I used Synthetic oil to start with and kept on getting an oiled plug as engine is inverted. A freind who maintains comercial two strokes for a living advised using a mineral oil . It  made starting very easy and I have used it ever since . I use the Comma two stroke oil mixed at 40-1 , at about £2-70 a bottle enough for about 5 gallons of fuel . I know someone will say synthetic is better , as I do with glow fuel, but it worked for me.
Thread: Ben Buckle Taylor craft
07/04/2010 22:29:39
Overall impression of kit . Plenty of good quality well cut balsa etc . Quite expensive compared  with what you get in some  ARTF's but good fun to build and a chance to use thos old diesel engines .  Not recomended for a novice builder  as instuctions on plan are a bit vague . Needs a few tweaks here and there to make a neat model . Its easy and a delight to fly , just as well as no throtle control means you flyit till it stops  What it really need is someone to sell coloured rubber bands !


Edited By Engine Doctor on 07/04/2010 22:50:10

07/04/2010 22:23:45
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07/04/2010 22:21:57
Whole model weighs about 1 1/2 lbs .A couple more flying shots
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07/04/2010 22:18:22
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Thanks David . All overlaps of the covering have been given a final coat of Clearcoat before painting the roudels and stripes . These were sprayed using Humbrol Mat and some frisk film for masking . Jump forward to maiden flight . A cold stiff breeze  . Engine set to a medium fast ( thats the beauty of a diesel ) and chocs away .

Edited By Engine Doctor on 07/04/2010 22:19:25

07/04/2010 22:08:56
I used some litho plate to cover the join between the windscreen and side screens . These were made from the tops of Christmas cracker boxes . The only trouble is finding a suitable adhesive . I finally used Bostik extra strong . I would have used Zap-a-dab-a goo .,excellent glue but it seem sthat its not being sold in the UK any more .If anyone knows differently  ,please let me know .
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07/04/2010 21:56:27
Another view
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Edited By Engine Doctor on 07/04/2010 21:59:32

07/04/2010 21:56:15
Airframe is now covered .
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07/04/2010 21:42:51
Once the tank is installed I fitted some lightweight snakes to the rudder and elevator .Then finished covering the airframe .The tail plane  and wings covered . Tail plane and fin have  not been glued on yet .
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Edited By Engine Doctor on 07/04/2010 21:44:36

07/04/2010 21:32:56
Next the Fuel tank. I make my own tanks for diesel fuel .Its really easy as older modelers will know . A good source of tin plate is sweet or biscuit tins . Ive made this tank  to fit the rear of the engine bay and allow the engine to be slotted in or out for any maintainance . Its glue in place with epoxy and gives around 8 min flight times . Not recommended for glow fuel  as tin plate will corrode /rust and mess you engine . Make a mock up of tank using thin card . When happy cut the tin plate with scissors . Top tip ! dont use your wifes scissors !!
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Thread: Super tiger 2000
07/04/2010 14:35:07
Nice model Duane I have similar pics on our club forum . If interested have look at click on the forum  and then "models under construction
Any ideas what it weighs so far ? Mine came out at 21lb 8ozs with the 50cc . Thats dry but with all batts etc only work needed is the roundels and weathering  Is your hurri the built up wing version or foam wing ?
Thread: Ben Buckle Taylor craft
04/04/2010 20:28:15
I have painted area prior to covering and fitting the screens . Ive also given all areas around the engine bay a couple of thin coats of Clearcoat to stop any oil soaking should oil get under the covering. I also apply a thin coat to the inside of the lite span to fix it around the engine bay . This has to be thoroughly dry before fixing and stretcing around cowling .Litespan will stretch well over compound curves with a little help of your hot air gun , it will take a lot of heat before splitting or tearing.
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