Well er how long is a piece of string hehehehe. Most of us go the other way ie start with a standard bike and start making modifications, you are starting with a modified bike and you are not sure what you have!!! If I were you I would try the following steps:

1. Contact the previous owner and ask him/her for a list of all the mods made.
2. Also ask him if he has all of the standard parts like the air filter cover and the exhausts (for instance) and I would even offer to buy them from him. This way you could put the bike back to standard trim.
3. Start keeping notes of everything you do to the bike away from standard.
4. Check the mixture by removing the plug, the colour tells you if the mixture is ok or too lean or too rich.
5. Adjust the variable resistor to 6pm, dont forget that this resistor will richen the mixture and if removed (or at 12 oclock turned anticlockwise) simply puts the mixture back to standard, which suts the pertol and partial throttle.

Then you can gather loads of other info on your bike my reading this wonderful forum!! And if you like I can try and help you more if you tell us what else has been done to your bike ok????

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....