Just setting up the topic.Trying to sort a few bits out.Update soon.

Good!!! Another Madman to join us!!!

Looking forward to seeing what you are doing.

regards

ralph

First mockup on a bit of paxoline as a base.
Started very well and ran quite smooth.I was very pleased and surprised.
Other bits should be here soon and I can continue.Got to run it in now.

First run

It's good when they run as sweet as that first time. You can see why they are popular little engines.

Doesn't sound too noisy either with that aero looking silencer.

I love the GX12...but i have found this tiny nitro engine called the Xray NT18, out of a 1/18 scale nitro car

http://www.ebay.co.uk/itm/NEW-XRAY-NT18-1-18-0-8cc-NITRO-ENGINE-w-CARB-GLOW-PLUG-/400233616218?pt=UK_ToysGames_RadioControlled_JN&hash=item5d2fc8535a#ht_500wt_715



Although it says 18, the actual physical size of the engine means it could be mounted in smaller trains then 32mm, and its a nitro engine, not diesel, as i know you can get very small diesels.

Have you already got a chassis in mind or even built one, and if not what kind of loco are you going to be building?

A quick update.
Three modifications today.
1...Raised the fuel tank higher to get a bit of gravity feed as well as pressure.
2...Fitted fuel filter after seeing the gunk in the tank
3...Fitted OS No10 Cold Glow Plug.

Ran through a whole tank of fuel with perfect results.
This is great fun.Will keep running the engine in whilst wainting for further parts.
Also got hold of a good syringe for fueling up.

....anther really good tip.
Clutch.
If you're bored,don't use your finger to see when the clutch 'bites' and how strong it is.
By the time the pain receptors in your finger have caught up....your fingerprint has melted
Not going to admit this to Wifey .

Be very careful...remember my thumb...I do.

BTW why have you used an OS no.10 plug when no.8s are usually okay.

I remember it well.(although you probably still have the scar )

I was having a bit of a problem with the engine cutting out after a while.I thought this might be the plug so I bought a few different types and tried them out.
The problem turned out to be a fuel problem,hence my raising the fuel tank up a bit and shortening all of the fuel feeds and breathers.
I added radio control today (another sharp learning curve) and apart from a scary partial heat siezure,everything is going well.
Although I've scanned the other posts for parts I've not actually read through them all.I wanted to learn the hard way (but still use proven hardware).
Hence the model I'm building will hopefully be a bit different from the others.
I'd never even seen a nitro engine work until I saw the monster,and apart from my steam engine (which was pre-wired) I'd never really bothered with radio control.
Now I have a radio controlled polluting menace
I raise my glass..cheers.

2 stroke nitro engines are very sensitive to the slightest bit of air in the fuel.
That's really the main cause of poor running.

They don't always like running at low revs on rich fuel as there isn't always sufficient pressure to pump the fuel through.

However too much fuel and they will flood easily.
On the green monster I raised the tank above the carb level so there was a gravity assist all the time and I kept the glow plug electrically energised. This allowed me to run the fuel pretty much as rich as I liked. Low revs, lots of smoke and less whiney noise, buts it's messy!

What was this 'partial heat seizure' you had?
Was that you or the engine?......
Why or how did it happen?

The low pressure must have been the problem I think.I have no trouble running a t low revs.I can quite happily get through a tank of fuel on tickover as long as I give it a bit of a rev every few minutes.
The heat siezure could be an inherited problem.Although the ebay listing said 'new' the starter spring had gone and it had a slight hesitation at the top of the stroke if you turned it over by hand.This isn't really a problem for me as this is the test bed for the project.Have got a bit attached to the 'menace' as it's called by the reat of the family
On stopping the engine (anther good question...how do you stop the bloody thing ) it decided to lock up.Stripped the whole lot down (much easier than the Harley I hasten to add) freed it up with some duck oil and a bit of love and care and it seems to be OK.

Radio Control

Must seem hilarious to you.I'm about 3 years behind everyone else

to stop the engine you can do any ONE of the three... 1) put finger over the carb. 2) cover the exhaust outlet. 3) pinch the fuel line and wait a few seconds. I usually cover up the carb as its the quickest and easiest way on shunt.

That engine was definitely listed as new as remember seeing it. And it's usually obvious if an engine has been used even a couple of times. The starter springs will go if one pulls on them too much. Don't pull out more than about 3/4.

Have you replaced the spring?

It seems to run fine from the video.

They get better/looser as they are run in.

Hi troy. Sounds like an interesting project. The siezing might just be a new engine running tight. From my RC aircraft days I remember that we ran engines very rich when new. Not only does the oil lubricate the engine but it actually cools it too. As has been noted above, the exhaust produces gunk, more so if you run it rich - this gunk is very hot and it has taken that heat away from the engine.

Using a rich mixture helps cool any internal combustion engine. This is mostly due to the vaporization of the fuel and the incomplete combustion resulting from the rich mixture. Fighter pilots used this trick when their cooling systems were damaged. Unfortunately, in a 4 cycle engine, it also washes away most of the lubricants from the cylinder walls, ruining the engine . But sometimes it got you home .

Since the nitro fuel has oil in it, rich mixtures don't cause wear problems.