Helio_s wrote:I do everything you said.
When I take out the spark plug, the engine turn correctly.
Is between the pressure in the piston and the power of the starter.
May be I need to clean the starter (rotor in the engine).
Maybe, as you think, the starter motor power is not up to full strength, but be VERY sure of those earth contacts first, and the contact in the starter solenoid can also get dirty and pitted reducing the current. You can check for this by using a fat cable (such as a jump-start lead) to make a (very) temporary connection across the two fat contacts of the starter solenoid. Take care as this will spin the starter motor.
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After you get the starter motor out of the car, first check the brushes (carbon blocks with a spring & wire contact). I don't know how long they are supposed to be, just that there should be a substantial part of the carbon remaining. It should press firmly on the commutator; that end of the carbon block will be curved to fit around the curve of the commutator. Make sure it s not fitted at right angle as then only a small portion of the carbon will be touching the copper segments.
Cleaning the commutator of a DC motor, like this one is not easy. The commutator is often blackened and you can clean with fine emery paper, but it is essential that you then clean off any emery cleaning residue with say petrol (no oil). Then with a fine squared off point you should scrape every gap between the copper segments of the commutator, and then clean again with petrol. Let it all evaporate or the motor might catch alight.
If you suspect it is not up to full strength, it might be a LOT simpler to trade it in for a refurbished motor.
Lotus seem to think that the only user service action is changing the brushes.
http://www.lotuselan.net/wiki/MA_-_Elec ... e_%26_Horn