Kiwi Mk2 Engine

[vcutajar]

Drilled the carb primary air passage (1.6mm).

 

[vcutajar]

Started work on the jet needle valve. Instead of doing it in one piece I decided to do it in two pieces; the needle shaft and the knurled knob.

First attempt at machining the needle shaft ended in a total failure but the second attempt was a success.

Started with a stainless steel 3mm rod and turned the needle taper (10 deg inclusive) (photo 1). Then I needed to reduce the 3mm shaft to 1.2mm and that is where everything went wrong on the first attempt. Second attempt was done by grinding the shaft instead of turning it. Unfortunately I do not have a toolpost grinder so a Dremel was clamped to the toolpost as shown in photo 2. A cutting disk was used for grinding. This method was successful as seen in photo 3.

Next the shaft was threaded 3mm (photo 4). Lenght of the thread was done by trial and error as no dimensions were specified on the plans.

 

[vcutajar]

Yesterday I finished the knurled knob for the needle shaft (photo 1).

Today I superglued the needle shaft to the knob.

Photo 2 displays all the parts of the carb and photos 3 & 4 the completed carb. I hope the carb actually works.

So now all the major parts of the engine are complete. I haven't done the float chamber yet. I will try the engine without it and if it works I might do it. I do not know if this happens to other people but the closer I get to finish the Kiwi the more convinced I am the project will end up as a glorified paper weight.

I still need to pin the gear to the crankshaft, harden and caseharden some parts (is this really required??), lap the valves and check for leakages and build the ignition system. I need to order somethings from the UK to do all these things.

 

[idahoan]

Nice work Vince!

I bet it feels good the have all those little parts nicely fitting together.

Dave

 

[metalmad]

Cool Carby Buddy

 

[vcutajar]

Hi Dave and Pete

Many thanks for the encouragement. Thm:

I needed it.

Vince

 

[ProdEng]

Good job on the carb Vince, a small and awkward bunch of parts to machine.

 

[vcutajar]

Thanks also Jan.

This morning I totally dismantled the engine and will slowly rebuild it putting in the finishing touches as I go along. First thing to do is to pin the gear to the crankshaft.

Vince

 

[vcutajar]

Haven't done much lately on the Kiwi as I am waiting for some items to arrive from abroad.

I did pin the gear to the crankshaft (photo 1). I also got myself a 12V ignition coil and condensor. Today I decided to test the ignition system using the Kiwi contact points and the sparkplug in the cylinder head. Hooked everything up temporarily using hook up wire (looks like spaghetti junction) and connected it to a car battery (photo 2).

Turning the contact point cam by hand, I managed to get a decent spark in the plug. At least now I now that the electrical part of the engine is working.

 

[vcutajar]

Finally back from Munich and in the meantime the things I sent for have arrived.

I got some bits and pieces to make up the high tension lead for the spark plug and some case-hardening compound (Kasenit replacement) from Chronos.

For the HT lead I got two options to connect it to the spark plug. Either a brass clip or a spark plug cap. I noticed that the spark plug cap I got is the resistive type. I am not knowledgeable about these things so could somebody tell me what is the use of having a resistor in the cap? Will this effect the spark? Should I forget the cap and use the brass clip instead?

Also, I wonder if anybody has used the Kasenit replacement compound I got. Any comments on it's effectiveness? Thanks.

 

[vcutajar]

Yesterday I tried case hardening the wrist pin. I am not sure if it made any difference so decided to leave it as is. After all this engine (if it ever runs) will only run for short periods.

Today I made two brass end plates for the wrist pin which were eventually pressed in. Also the two piston rings were fitted on the piston and the piston fitted into the cylinder. It was not difficult to press the piston into the cylinder and the miniature ring compressor I had made was not used.

I think it's normal (remember this is my first engine), the piston with the rings installed, is a bit more stiff to move in the cylinder.

 

[vcutajar]

Did some more reassembly of the Kiwi.

I was going to fit the crankshaft but then I remembered that everytime I needed to untighten either the flywheel nut or the special nut retaining the gear I always had problems because I could not stop the crankshaft from turning. So I milled two flats on both threaded extremities of the crankshaft (photo 1) to lock the shaft from turning with a spanner.

I then fitted the conrod to the crankshaft (photo 2) and then mounted the crankshaft to both halves of the crankcase (photo 3).

Photo 4 is the partially assembled Kiwi back on its mount.

 

[idahoan]

Looking good Vince; thanks for the updates.

I'm still fallowing along here; I'm hoping to get an update to my project sometime this week.

It looks like it won't be long now and we will hear the good news of another engine coming to life.

Dave

 

[vcutajar]

Thanks Dave for hanging in there.

Did some rough timing of the camshaft and also fitted the ignition timing cover with its' associated mechanism (photo 2) and set the ignition cam position.

I also made up the H.T. lead using the NGK resistive spark plug cap.

All that remains to be done is grinding the valve seats.

 

[JaamieG]

Fantastic build and step to step tutorial Thm:
I just read it all and enjoyed every single step. Absolutely fantastic.
Thanks for sharing all the details of the process.
Cheers,
Giacomo
Sweden

 

[vcutajar]

Thanks Giacomo for the kind words. Happy that you enjoyed my journey.

Vince

 

[vcutajar]

Only valve grinding into the head remains but I have been side-tracked by some big-name games for the Xbox that came out this month and I could not resist them.

Shoot away

 

[vcutajar]

Had a break today from the video-gaming world and back to the machining world.

I fitted the valves into the head using 600 grit grinding paste and an MT3 drill chuck. Put the valve in the head and clamped the valve from the end of the valve stem with the drill chuck (photo 1). The inlet valve did not need a lot of work but the exhaust valve needed a fair bit of work.

Used a vacuum hand pamp to check for valve seating (photo 2). The valves leak from 20" vacuum to nearly zero in 15 seconds. Hope this is not too much.

I then gave the head and valves a good cleanup in the ultrasonic cleaner to remove any traces of the grinding paste.

 

[vcutajar]

Today I re-assembled the cylinder head and bolted it to the engine (photo 1 and 2).

So I decided to try and start the engine to see if at least it would make any encouraging noise. I connected a plastic tube to the carb and filled it with fuel (unleaded gasoline) and gave the engine a twirl with the electric drill. Bad news. Not even the slightest indication of combustion in the engine.

Decided that further work on the engine will stop until I troubleshoot what is the problem.

Started off to check if the sparkplug is working. Took the sparkplug out and ran the engine again. Yes there is a spark but the problem is I do not know how a good spark should look like. Replaced the ht lead (which had a resisitive cap) with common wire and tried again. Again same spark (I think). Checked the plug gap and it is set at 0.5mm. Should I change this gap?

 

[Gedeon Spilett]

what a smart thread !
it looks like an engine ready to run, there is no longer any petrol at the pump ?