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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: Help please with Thunder Tiger GP42
10/08/2020 19:41:01
Posted by Paul Marsh on 10/08/2020 15:24:15:
Why would anyone want to lower the compression? The engine works ok as it is, and probably upset the running, unless you want to convert it to petrol.question

The gasket is used to make seal as they should be annealed when new and conforms to both surfaces . Its not for lowering the compression in this case Although many engines from yesteryear gave you a couple of different thickness shims for use with different types of fuel plugs etc.

A new gasket/ shim can easily be cut from a small piece of annealed litho plate or as said earlier some aluminium pie case although it should be a thicker type like a ali baking tray . Use the line for a pattern and a scribe . Cut the center out with a scalpel then cut the outer with a pair of sharp scissors . Not bad engines for their day but took forever for the piston liner to fully run in .

making a head shim using this method has sorted a few four-strokes over the years that kept on throwing props.

I have an Enya 60 4c in a 2x Lady Bird That was unusable as it kep throwing the prop. I tried everything form different fuels to plugs and two washer under the plug etc to no avail . I then cut a shim from litho plate andthe engine is transformed with no loss of power .

10/08/2020 09:20:30

The original head gasket / shim was made from aluminium. Using the softer gaskets may cause head distortion. Are you sure the original is not stuck in the head ? They get pressed in and can look like the casting.

I would suspect that the replacements are thicker ? This would retard ignition and loose some top be power . On the plus side engine will be very docile and have a good idle.

Thread: manual
09/08/2020 10:23:09

What spares do you need ? Things like bearings ,oil seals etc are readily available from any bearing supply specialist. Try " Simply bearings". Carb recon sets , carbs are usually Walbro clones, can be found on eBay . All the other internals and major parts likealike piston and cylinder ,Conrod etc are usually generic parts used in industrial two strokes used in strimmers and the like. Gaskets are easily made from suitable heavy gauge brown paper.

If parts like crank cases are broken then you may have trouble. I have had to repair some cases that have become obsolete in the past .

Advise what parts you need and someone on here can advise.

Thread: LED wiring
08/08/2020 20:10:01

Google Lipo battery balance lead wiring . It should then become clear idea

Thread: WD40
07/08/2020 19:35:05

Best penetrating liquid is /was Plus Gas . Not sure if the new stuff is as potent as the old stuff .

07/08/2020 14:05:27

I vaguely remember when WD 40 first came out that it as featured on the BBC "Tomorrow's World " program . They sprayed the insides of an electric drill then put it under water while running . Usual comment " don't try this at home" were used before the shot. Imagine that being shown on TV today? WD 40 has certainly stood the test of time and seems to be used as a generic name for penetrating maintenance sprays ; like Hoover is used for Vacuum cleaners.

Thread: OS40FS
05/08/2020 11:46:31
Posted by Doctor Chinnery on 05/08/2020 11:15:26:

Shame there don't appear to be Hayes or For Dummies publications on the subject.

That would be a popular publication but with Haynes manuals current quality probably not that good ,JMO.

05/08/2020 11:44:18

The link on piston pin removal is ok providing the pin is not siezed /gummed into the piston. Lots of heat , plus gas etc needed in those cases. Good luck .

PS a soak of all the bits in cellulose thinners will remove any Castor oil . It doesn't dissolve it if its gummed but pickles it a bit like putting cellulose paint on top of enamel and it then brushes off easily.

Thread: Best wet and dry sandpaper?
04/08/2020 13:37:06

Wet dry paper on a roll ? Never heard of that . Always bought quality paper from car paint factors. Sit down before asking the price smiley especially 3M , always way more expensive for all their stuff.

Thread: Futaba R/C set
03/08/2020 19:03:26

You can plug the battery in any free space on the Rx . To use channel seven just use a "Y" lead for the battery and servo. Great Tx and easy to set up.

Thread: Battery connectors
31/07/2020 09:20:47

I used Deans exclusively for years as changing them for XT 60 was a longish job. Then one of the deans connector spring tabs broke and the connector got very hot very quickly. Luckily I spotted it as it could have caused a fire in the model. Since then have been changing over to XT 60 and a few XT 90 . IMO a far superior and safe plug that's easier to grip when pulling apart and the newer versions have a decent cover for the soldered joints.

Thread: build to remember
27/07/2020 11:54:51

The Vic Smeed Mamselle is ideal for the Mills and lightweight 2 channel radio . Planes available on OuterZone as are many other model types . Good luck and let us know what you decide on and some pics of the build ?

Thread: How to post a Wanted Ad
26/07/2020 18:48:46

Please be careful of any replies to your wanted add . The scammers seem to pounce on them .

Thread: Irvine 40
26/07/2020 10:35:24

I have some old irvine carbs in my spares box . Ill check and see if there is a needle valve spigot in there later today . If I have one I'll pm you .


25/07/2020 13:18:20

The little "O" ring should screw inside a tube and make a seal . If you can see it when the needle is a couple of turns out then its either the wrong needle or something is wrong.

Thread: Bending Pipes for Fuel Tank...
25/07/2020 13:15:19
Posted by David Gilder on 06/03/2013 16:30:53:

Melt a candle into the pipe.

When cool, bend. The wax will prevent the pipe collapsing.

When bent, reheat the pipe and the wax melts out.

This is how they bend the pipes for brass musical instuments!!!

Hope that helps!!


Edited By David Gilder on 06/03/2013 16:32:16

Thats a good tip yes

Thread: Swann Morton blades
25/07/2020 12:45:23

26 and 10A do most things .Cant get on with the No 3 or 4 blade as keep cutting finger were the sharp bit goes under the handle . Most used handle is a fixed handle with a bulbous molded plastic grip, Not shown on the Swan Morton website.but was I believe a genuine Swan Morton handle . They now list a stainless steel version instead.

Thread: Masks
25/07/2020 12:31:34

Hi There are plenty of designs available on line . My daughter-in-law made a few . I believe the material should be of a type that will allow moisture to be absorbed so trapping any virus that is airborne on a water droplet/aerosol. Wont give you immunity but if it stops me spluttering droplets when in shops etc then they can only help.

I was amazed yesterday at the number of people in shops etc that were not wearing any mask ! Shop keepers weren't saying anything to them but who can blame them ?

last evening there was an add on the telly selling 50 masks for £13 . Dont know if they are the "specials " in the videos thoughsurprise

Thread: Carb tuning
23/07/2020 16:28:15
Posted by Richard Clark 2 on 23/07/2020 15:59:02:

I like pumped engines but the pump diaphragm is a built in failure mechanism. Particularly so if you use 'after run' oils. (Three in One oil destroyed my fishing reel 'rubberised' handle in seconds.)


If your using Three in one oil as a after-run oil your asking for trouble . Its horrible stuff and best suited for squeaky door hinges . Its acidic/ sets like varnish and will probably destroy any diaphragms or rubber bits by making them go hard or brittle . Use a proper oil designed for after run or Air tool oil . If treated properly diaphragm pumps are not "built in failure mechanism" . They do require replacing occasionally and are a serviceable item

Sorry Charlie . This has gone completely off topic . There are numerous post on carb tuning try the search facility . MDS engines did have a problem with their carbs due to poor fits and some are almost impossible to get right. They were cheap engines but many still run perfectly well providing you dont ask too much of them . High revs and tuned pipes will kill them very quickly . 


Edited By Engine Doctor on 23/07/2020 16:39:19

Thread: OS 48fs problem
21/07/2020 20:14:57

If the glow plug etc doesn't work then it could be over compressed . First try a second copper gasket on the glow plug . If it still does it then it worth taking the head off to check if a head shim/ gasket has been left out . This will cause the problem . I often get engine to sort that have been Stripped by the "Club expert" and the head gasket /shim is missing . Probably thrown away with the cleaning liquid ! I had a few back when they were current and occasionally one would be a so and so with prop throwing. a second head shim always sorted it..

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