I own a 1999 make RX-135 and have clocked 91, 000kms.The engine was opened in 2005 , the bore got a slight modification like, the air intake chamber was slightly increased in dia for more freeness in the accelaration between gears.After this change I have been using more 2t mixture in petrol. The bike is mainly maintenance free, provided you service it once in 3 months. I have inserted glasswool cloth in the silencer core to decrease the sound, after that I see a lack in the pickup which I used to have when I had a open core, i m happy with its maintenance free behaviour, Once in a short distance, in a main road signal of chennai, I raced with a pulsar 150 and I won, it was a surprise for me as I was thinking that pulsar will have a better pickup, the main advantage I had was the timely * quick pickup and the correct timing of gear change.But I know if we had continued the race the pulsar would have won as it is good in the long runs.if you do not bother about mileage and also about the classic looks and sound that it emits, you can keep fueling it and keep riding it all day.All round rating I will give 3 out of 5 for the 135 - 4 speed.