hi, i have a pocketbike and i want to convert the engine to glow fuel, what are the engine modification than i have to do, and what tipe of fuel?(i have 2 bottles of methanol, 1st one have a 15% nitromethane and the second have 20%(*sorry about my english...)

when you say methanol is it glow fuel?(15% nitro 18% oil and 67% Methanol) if so I would try to make a 33% glow fuel 66% petrol(gasoline) mix and try it on your engine you will gain power with this mixture.

yes is glow fuel, but its very expensive :s , can i make another mixture with methanol and another things? (i want to use the pocket bike for drags )

Here 10/10 glow fuel is about $9.00 a gallon and gas is $3.20 a gallon.
So your looking at about $15.40 for 3 gallons or close to $5.15 a gallon.

For what your getting that's cheap. You probally won't burn a gallon a day
and probally 1/2 a gallon when you get everything set up right.

Make the standard 2% mix, but use a 70/30 ratio for gas/methanol for starters. You can buy methanol in AKI in 1 liter bottles.

here in portugal one gallon of glow fuel with 25% nitromethane is 38€

If you run 25$ nitro you will damage the engine.
You need some where between 10 and maybe 15%.
I would start off with 10% and see how it goes.
The piston in your pocket bike is probally a cast piston
and will not stand up to to much abuse, pre-ignition.