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Old Dec 30, 2002, 07:12 PM
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Nearly another 'how to tune my engine' question

Hi all,
I really need some advice on this.
I have 3 Traxxas nitro cars, a Rustler, 4TEC and of course the TMAXX. All
have the TRX 0.15 engine in them.
The Rustler runs great - very fast very powerful - it is also the oldest at
3 years old...
The 4TEC is not bad - but seems to have (and always has had) huge amounts of
compression compared to the other two - once running it tunes in and runs
very well, it is just a bit of a pig to start sometimes.

The TMAXX though is odd. When I first got it (about 9 months ago) I could
run it all day with no problems at all, I would have said it was the best of
the 3.
It now starts very easily and will run quite well for about 5 minutes. It
then starts to sound as though it is running hot (clacking sound, uneven
tickover) and the water drop test suggests that it really might be a bit
hot. To compensate for this I richen the mixture (top end) and obviously it
makes a difference to the power, but does not seem to cool the engine down
and I still have the uneven running at tickover. I have tried adjusting the
bottom end mixture instead and all I do is get a truck that will stall if I
accelerate too hard and is still hot. The basics of this problem are if I
set it rich enough to keep cool the thing has no power and splutters like
The driving I do is a mixture of high speed and low speed - not that this
seems to change the symptoms.
All the engines were run in the same and exactly as per the instructions.

So far I have done/ checked for...
Dirt in the fuel line
Dirt in the carburettor (disassembled and cleaned)
Damage to the mixture needles
Dirt / damage in the engine (not disassembled - just looked for score marks
on the piston and crank)
Ensure the air filter is clean
Leaks in the fuel line etc
Binding gear train
Binding clutch (at tickover)
Avoiding driving on grass (not that I have done this much anyway)
Reset to factory tuning settings and start again

I use 20% blue thunder fuel in all the cars and wonder if fuel is
contributing to the problem (not that I have had any problems before), but
why would it work in the other 2 cars?

Sorry to post another subject on 'how do I tune my engine' but I am getting
very frustrated with this now.
Please, please help me with this, it is spoiling my fun!!