posted some of this over in the yahoo group but thought i would put it here too.
i am just about finished in my performance mods for the rattler, i cant honestly see much point in doing anymore as i cant keep the front wheel down from 0-30kph top end is well over 100kph i havent dared try to go further as the engine is still technacially running in so can only do short bursts.
the exhaust i ended up getting was from a bws or zuma as its called in the states, it required some fabrication but im pleased to say it didnt require using the old restrictive exahaust in order to fit.
heres a picture of it, its rather odd looking and has a small expansion chamber inside the can and is very very loud, sounds like a MX racer.
i have had to change the oil injector pump for a higher flowing one, so i dont need to do silly 50:1 calculations at the pump every 2 days!.
the compression has been raised to 8.8, a more powerful spark plug thing (dont know the name but gives 4x more power to the spark plug) and some of the drive train has been lightened and modified, i cant say what was done as i dont speak chinese and they dont speak english, i just know they spent a few hours with my transmission and machining tools!.
the problem i have is that 2000-4000rpm its stuttering and not reving cleanly, my clutch was engaging at that exact point and causing a rather horrible on/off flip over start, to counter this some race spec clutch springs have been installed, the clutch doesnt engage until around 3000rpm, which doesnt cure it but helps alot and also annoys everybody as i scream before going anywhere!.
the reason for the stuttering is the carb and exhaust combo, the exhaust is designed for high rpm, the engine is designed for high rpm......the carb is not,
now this is what im told by them so if you might know a different reason for this please tell me!.
so im either gonna bore out the carb another 2-3mm or buy a new bigger one maybe 24mm.
wow long post, you would think with all the mods i have done i would be facing a HUGE bill!.
so far i have spent less than $200!
exhaust cost less than $45!
-EDIT- sorry was wrong i meant $90 but its brand new!