Member postings for Roger B

I think that the radiator, fan and finger guard were bought separately. The fan and guard probably came from Conrad and the radiator from Amazon Germany (I live in Switzerland). This allowed me to choose the size and voltage. I am using an 80mm radiator which is borderline. You should probably think about a 120mm one.

I made the water pump for this engine, it is built into the distributor drive. I have used a pump like this with a 5V supply as a fuel feed for another of my engines. At 12V it should supply more than enough.

bedienungsanleitung-207894-modelcraft-modelcraft-kraftstoff-getriebepumpe-benzinfest-foerdermenge-06-lmin.pdf (conrad.com)

I fixed a small filler/breather to the top of the radiator but otherwise I just use the reserve that is there.

Carburettors for small four strokes are a problem. Most commercial ones are designed for high revving two stoke engines. I built a small constant depression (SU type) carb for my twin which worked well. It is now running with mechanical fuel injection.

Computer CPU cooling radiators are cheap and work well along with their electric fans. In this case there is a gear type water pump for circulation.

Excellent

There should be sufficient vacuum unless the throttle is open too far. This is a similar carb and tank set up on my 12cc twin. It needed an initial prime with the air intake blocked. After that the fuel pipe would stay full for a couple of days.

That looks to be a reasonable set up as long as the tank is less than half full.

The system will prime if you choke the air inlet but does not seem to get enough fuel to run. Could there be an air leak between the carb and the cylinder head? Have you checked that the needle moves in and out of the jet and that there are no obstructions.

How high is the fuel level in the tank compared to the carb? It sounds like there is too much fuel being delivered.

Can you post some pictures of the set up?

10-15° before TDC is fairly typical.

I am surprised you are not getting any signs of firing. Normally something should be happening even if it won't make a sustained run. It has run so the basic mechanics should be ok unless significant leakage has developed past the valves or pistons.

One suggestion from another forum was to hold a flame by the exhaust whilst cranking to see if any burnable mixture was getting through. I haven't tried it myself but generally turning the engine over with a drill and gradually opening the needle valve has resulted in a start.

Has the engine ever been running or don't you know? What carburettor has it, the Westbury one?

By a dogbone do you mean the bar and pin that goes into the starting dog?

How good is the compression? The usual description is that it should be 'springy', something like this:

https://youtu.be/1Z3wXPAkC2U

A CDI and coil may trigger differently, the coil will spark when the contact opens a CDI may spark when it closes.

I suggest you make a simple check of the operating sequence. Remove the spark plugs and rest them on top of the engine so you can see when they spark and then slowly turn the engine by hand.

The inlet valve should open at or just before top dead centre and the exhaust valve should be just closing.

The inlet valve should close just after bottom dead centre.

The plug should spark just before top dead centre.

The exhaust valve should open just before bottom dead centre.

The exhaust valve should close at or just after top dead centre and the inlet valve should be just starting to open.

Repeat for the second cylinder.

If you don't get this sequence some deeper investigation of the camshaft and ignition system will be required.

Good luck for your first running trials

Have you tested the injection system yet? Do you get a reasonable spray pattern?

Still following with interest having spent several years playing with small fuel injection systems

Is it possible to make the gearbox output coupling easy to disconnect? Possibly one of those couplings with two chainwheels and a short length of duplex chain, 4 cap heads and a couple of splitpins and you can tow as fast as you like.

Have you asked Alan Keef, unless that's who you are working for

Homepage (alankeef.co.uk)

They have supplied many NG Locos

That looks good

So many tolerances will affect the valve timing. For a slow speed engine the timing is not very critical, with good compression and good ignition it will run.

TECO in the Czech Republic still make the milling machine. They may be able to supply the part you need:

http://www.tecoznojmo.cz/english/vf400.php

I have used stainless steel TIG welding rods. You just need to find a friendly welder unless you want to buy 1kg.

As a quick show and tell I drilled a 0.3mm hole through a piece of 2mm brass using a Proxxon 0.3 mm drill bit at 8 000 rpm. The Rohm chuck held that with no problems but would not hold a 0.2mm bit (I generally used reinforced shank at 0.2mm or less so it is not a real issue.