Hey, i am a Marauder owner myself (love it) and wanted to do the same, this is the only aqnswer i've found online. i'm a big guy and i can get 65mph out of mine, downhill with a strong wind at my back. anyway, this is quoted from another site.
"Man, how come us guys are always trying to make what we got go even faster??? LOL... By de-restrict, I assume you are talking about puching out or altering the exhaust? Ok... the 125 Marauder is a single cylinder 4 stroke cruiser. Yes it is possible to do it. As for safe? Well... your son won't end up hurt, but the engine might. When street bikes are designed, there are certain factors that are considered. Emission outputs being a major one. Your sons bike has been designed for optimum performance with the exhaust, carb and air intake system it now has. The first steps to souping up a cruiser are to install a high performance exhaust, remove the airbox and install aftermarket HP air filter (such as a K&N)... and lastly (and most difficult) the carb has be rejetted to match the changes in the exhaust and air intake. I don't think there are too many places that sell performance parts for a GZ125, as the bike was never meant to be a racer. I personally would not alter it from stock, as Suzuki has put a lot of time and money in R&D on their bikes... besides, the final increase in power could prove too much for the simplistic frame and forks... in other words, the bike was designed to handle 10.2 HP @ 9000rpm... and remember, for every change you make to the flow restriction on the exhaust, you will prolly need to match it with a rejet on the carb... Hope this was helpful Wilson!! Oh and tell your son to slow down, ya can't see the scenery if you're squinting!!! LOL"
zero
February 2009