Kiwi Mk2 Engine

[vcutajar]

Hi Gedeon

Thanks for coming by and commenting.

Today I did some more troubleshooting. I increased the sparkplug gap from 0.5mm to 0.6mm and had a closer look at the colour of the spark. It is whitish with blue edges. I need to get a different ignition coil to see if it makes any difference.

Whilst turning the engine with the hand drill to see the spark, I realised something. OMG. I have been turning the engine in the wrong direction . After some unprounoucable phrases I cooled off a bit and put some fuel in and gave it another try. It still did not start but I think at one time I heard an encouraging splutter coming out of the engine.

I am now seriously thinking of getting a commercial carb to replace the one I made. Whilst I decide on which one to get from the UK, I removed the cylinder head and started lapping the valve seats with toothpaste to remove the small leak that they had.

 

[warf]

Impressive work. You might see how much compression it's got. And try fule out of a syring or starting fluid if you suspect the carb.

 

[vcutajar]

Hi warf

Thanks for your comments.

You might see how much compression it's got.

I would love to measurre what compression I have at the moment but from what I understand the commecial compression testers used on car engines do not work well on small model engines. Having said that, if you have a way of doing it, I would love to hear it.

And try fule out of a syring or starting fluid if you suspect the carb.

Can you please explain what you mean by this. Any suggestion is most welcome to get my first engine running.

Vince

 

[Gedeon Spilett]

I suggest that you make a copy of the valve diagram on hard paper, put it between 2 washers on the crankshaft with the correct position of TDC, and turn the shaft (in the right direction!) then check that valves open and close at the designed angle. It is simple to do and reassuring.
You should make a list of everything that works well!
Spark, and spark timing, valve opening, valve seating, compression…what remains after?
I bet that your engine is ready
Cheers

 

[warf]

Starting fluid is used primaraly by notherners to start cold engines, it comes in a spray can at your local auto parts dealer. You squirt it directly into the carb throught. If compression and spark are good and at the right time the engine will fire a couple of times at least. Don't try to run the engine on it for any preiod of time because you cant adjust the mixture like a carb, and a lean condition could damage the engine. Just use it for trouble shooting. If it dose fire "BANG-BANG" then your carb needs help.
If it dose not fire then its compresion or spark timing. Sounds like your spark is sufficent strength are you sure its at the right time? compression could be valve seal or valve timing or ring seal .

 

[Cogsy]

If you tip a small amount of fuel directly into the spark plug hole, then replace the plug and lead and try to start it, it will produce a few fires and maybe even a second of running as well, if everything else is ok.

Compression you can just 'feel' but without a reference you won't know how much it's got. You can try blocking the carb and exhaust and turn it over, seeing what it feels like, then try it only blocking one or the other. If there is a difference between the two it will show you which one of your valves is leaking.

Good luck - I'm sure you'll get it running.

 

[vcutajar]

Thanks guys for the tips.

At the moment I am working again on the valve seating. I just finished the inlet valve and now it will leak a 20" vacuum to near zero in 30 seconds. Next time I will work on the exhaust valve and try to get the same result.

Vince

 

[Charles Lamont]

Well, I'm on the edge of my seat. If I have to stay here too long it is going to get uncomfortable.

 

[vcutajar]

Nice one Charles. I suggest you stand up a liitle because it looks like it's going to take a long time.

Haven't done much lately. Both valves now leak a 20" vacuum in about 30 seconds and I also reduced the gap of the ignition contact point. Sometimes when trying to start it it gives indications that it wants to start and sometimes I also see flames coming out of the exhaust port but that's all.

I am at the moment experimenting with different valve timings.

 

[5mall5nail5]

This is very interesting - I do hope you figure it out. can you setup indiactors and confirm your timing? Flame out the exhaust sounds like too much overlap or too late of total timing.

 

[myrickman]

Vince- I showed up late to this party but after an hour of browsing the posts of your progress, all I can say is WOW. Very impressive build! The carb is a work of art. I picked up a lot of good fixturing tips from your very extensive and complete documentation. I would not sweat having the valves be super leak tight. While they hammer against the seats during running they should tighten up a bit more....? I like the design and the lines. Also like your candor about not starting some bits until you feel the inspiration..... MM

 

[vcutajar]

Thanks guys for having a look and the encouragement. Troubleshooting has been painfully slow. I make a small adjustment give it a try and then give up for the day. For example today, I took off the piston rings cleaned them up with 800 grit sand paper and fitted them back again. It seemed (or it just could be my imagination) that it improved slightly the compression. Still it did not start. It tries to start but is not self-sustaining. During these holidays I am getting an expert (in real engines) to have a look at it to see basically if the spark and the timing are good. There is something else I can try, but I am leaving it as a last resort.

Although I haven't given up yet, every day that passes the reality that this could be a glorified and expensive paperweight is setting in.

Season greetings

Vince

 

[KBC]

Thanks guys for having a look and the encouragement. Troubleshooting has been painfully slow. I make a small adjustment give it a try and then give up for the day. For example today, I took off the piston rings cleaned them up with 800 grit sand paper and fitted them back again. It seemed (or it just could be my imagination) that it improved slightly the compression. Still it did not start. It tries to start but is not self-sustaining. During these holidays I am getting an expert (in real engines) to have a look at it to see basically if the spark and the timing are good. There is something else I can try, but I am leaving it as a last resort.

Although I haven't given up yet, every day that passes the reality that this could be a glorified and expensive paperweight is setting in.

Season greetings

Vince

Vince ,
Don't give up we are all rooting for you, it took me 4 years to get my Flash Steam plant running and installed in a boat, it now is in the 40 mph region and very dangerous running on R/C so it's laid up until I consider what to do with it but not 4 years wasted, so keep at it.

George.

 

[vcutajar]

Merry Christmas to all

Just an update for those following my trials and tribulations.

The engine runs when trying to start with the electric drill but is not self-sustaining. My friend said that the spark and the timing are ok but just needs a bit more compression. When making the crankcase, I left the cylinder platform about 1mm higher to reduce the compression. Westbury suggested that a lower compression would make an easier starting engine.

Well today whilst dismantling the engine to mill off that extra height on the crankcase I had another idea. Why not make a new longer piston. So the plan is to make a new piston from aluminium bar stock. I will make it even tighter with no clearance at the top and make it 1 mm longer to cater for the extra material on the crankcase cylinder platform.

 

[idahoan]

Hi Vince, Good compression well never hurt; as long as your engine is apart how is the wear pattern on the rings? Are they contacting the cylinder fully; are the end gaps reasonable when installed in the cylinder?

If you are not getting a good seal on the rings it may be a simple ascorrecting that. If the rings are seating well; you are probably on the right track.

Keep us posted,

Dave

 

[vcutajar]

Hi Dave. Seasons greetings.

Yes, the wear pattern on the rings is uniform which should indicate that they are seating properly. In an earlier post I had said that I touched the rings with sand paper. This was done as the wear pattern was not uniform. The ring gap is minimal. I had asked a question about how much it should be on this forum and I had set it even less than that.

Today I had second thoughts on the course of action I was going to follow. I will sleep on it and see tomorrow.

Vince

 

[vcutajar]

I haven't given up yet. The recent holidays put a damper on things and had hardly any time to continue troubleshooting. Well since my last post I have milled off the excess metal I had left on the crankcase cylinder platform. Did not make much difference.

Decided to make a new piston from bar stock but had to wait for the holidays to finish to buy the material as my usual supplier was closed. Piston finally finished and it is a tighter fit then the old one. I did not give it the usual clearances and will see what happens.

Photo 1: Milling the slot for the conrod. Used a 4 jaw chuck which was clamped to the mill table.
Photo 2: Reaming the hole for the wrist pin.
Photo 3: Both pistons. The new one is on the left.
Photo 4: Same as above.

Installed the piston in the engine without the cylinder head and using an electric drill ran the engine for a while to give the piston some running in. Put the cylinder head on and there seems to be better compression. Connected the fuel line to the carb and believe it or not my electric drill gave up its ghost.

So now I have to get myself another drill before trying to start the engine. Just my luck.

 

[vcutajar]

Well, today I went out and bought a new electric drill. Hooked it up to a plastic pipe. Filled the pipe with fuel (no tank yet) and gave it a twirl.

OMG it runs. Only for short periods, as it runs out of fuel quickly, but at least now I know that it works. Unbelievable.

Now I can continue and finish it up. Still need to do the exhaust pipe, a base and some sort of fuel tank.

Video of the first run:

[ame]http://www.youtube.com/watch?v=KDr3Ga_CTBA[/ame]

And the second run:

[ame]http://www.youtube.com/watch?v=rbQ_hjSGgZ8[/ame]

I hope this is the correct way to show videos.

 

[Henry]

Nice, nice really nice to hear your engine!!! finally was the compression!

 

[vcutajar]

Thanks Henry. I am over the moon at this time. My first ever model engine coming to life was an undescribale (is this a proper word?) moment.

Yes the problem was not enough compression. The new piston fixed that.

I should make the Kiwi as my avatar now that it is running.

Vince