running in tt 39 probs

[troggmaster]

hi guys can anyone give me an idea of which glow fuel to use on my tt39.
the problem ive had is on idle.
it seems to idle ok but the revs will drop suddenly and then pick (almost like a stutter) throttling up is clean and crisp.

the only way around it is to set the idle higher but this engages the clutch slightly ?? any ideas fuel type is model technics contest 10
cheers

[Ade_Law]

the trick to getting an engine to run nicely is;

good engine
quality glow plugs
quality fuel,
quality muffler.

Unfortunately contest 10 can cause some problems, it will run but I consitantly have problems getting engines to run cool, constantly with plenty of power available.

I prefer Enya 3 plugs as I have never had an engine quit in the air due to a old/damaged enya 3, OS 8 work ok too.

Lastly there is the muffler. 2 stroke engines are greatly affected by how the muffler deals with the pressure pulses. Again the stock 2 part mufflers do work ok but for ease of setup and consistancy of running from day to day one of the one piece ali mufflers are a better choice. I prefer the stainless steel Zimmerman mufflers, they are strong, easy to keep clean, quiet and powerful.

it is difficult to tune a motor remotely. The 2 adjustments on the carb interact with eachother which can make life a little difficult.

If you leave to idle for longer does the stutter of of idle get worse? I would say you are likely to be a fraction rich on the idle screw.

but... and this is a big but, on the TT39 the idle screw affects the mixture at the hover point too. It is common for the hover mixture to be a little lean in the hover, this is compensated for by richening the idle screw.

to check the hovering mixture you need to hover it for about 15secs, land and put your finger on the back plate. You need to be able to hold your finger on the backplate of the engine for a minimum of 5 secs without it burning your finger.

I would also check the full power mixture by doing some 15sec climb outs followed by a quick landing and checking the back plate temperature.

running a fuel such as magnum 12 or wildcat 15 will reduce the engine temperature a good amount allowing you to lean it out a little more and getting more power.

so to sum up, your mixture is a compromise between a reliable pickup off of idle and an engine that runs nice in the air. The problem is that an iffy pickup is just a pain, if the mixture is wrong in the air it can quite easily kill the engine in seconds.

Ade