A few things to think about if you havent already tried them.
Check needle settings against CEN's reccomendations http://www.cenracing.com/downloads/E...Doc%20NX26.doc

Have you been using the same glow ignitor the whole time or have you tried different ones? I know I have 5 glow ignitors and I've had times when none of them were charged enough to start my engine and I couldnt figure out what was going on. And I had one with a bad battery that wouldn't fully charge.

After you try starting it with no success, take out the glow plug and turn the car upside down with you hand on the cooling head. Give it a few pulls and see if fuel comes out to see if its flooding or starving.

If it is getting fuel, try removing the air filter and starting it in a clean dust free place(not outside in the wind) And check your exhaust for any blockages. Restricted air flow can easily cause flooding.

Check that your cooling head is tight, its hard to tell if its sealing or not. Take off your carb and check for dirt where it connects to the engine, and check the O ring that should be on there(I think the matrix should have one...). Make sure the carb gets put on sufficiantly tight.

If none of that works and as you've said you've tried different plugs(I'm assuming you've tried hot plugs). Then I guess just play with the needle settings, although im sure you've done that. If its flooding lean it out and vice versa. Probabaly not necessary to tell you that but sometimes things get overlooked when you get frustrated.


I have an OS .18 that had issues and eventually I found that it needed far leaner needle settings than what was reccomended just to get it started until i had about 15 tanks in it.

Good luck!