Motorcycle Repair: suzuki gn125, motad exhaust, c spanner

Question
how cant i get my gn 125 to go faster with out spending to much money. As i find that it lacks power when pulling away and at top speed

Answer
Jason, the only thing I found on the web was that someone had put a MOTAD exhaust on his bike. See comments below.

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Bike: Suzuki GN125
Name: Richard
Year Of Bike: 1994
Miles: 7-14000miles
Rating: 8
Mods
Motad Exhaust

Carberation
When I got the GN it had obviously been ridden as per riding school instructions (Short shift to fifth within 10m of starting) and as a result was coked up to the eyeballs. A few months with the occasional blast at full throttle (no risk of breaking the speed limit)had it cleared and even better the new motad exhaust made a nicer noise and took top speed up to a respectable 75mph (flat over tank and I weigh 60kilos)Took a long while to warm up, often had to ride with the choke open for 15min or more and for some reason blipping made the idle speed drop. probably needed the carb cleaning.

Brakes
Progressive braking? whats that then? Front disc felt all or nothing, matched by the rear brake giving no feel before locking up. Front improved after a service but the rear was always to be used with caution.

Handling
Even for my slight weight I could have done with a C spanner to add a touch more preload, you could feel the bike squatting in hard corners. Stock tyres are awful in the wet, slip sliding on almost every corner and watch out for road markings. they last well though. the front end of my bike was very good, not heavily loaded but the forks seemed well adjusted, not much dive at all. Otherwise the bike was comfy, on longer trips I would put my feet on the pillion pegs to stretch but apart from that it's actually a nice bike for very easy touring.

Comments
As a learner machine or cheap commuter this does really well. tank range is massive and even todays fuel prices don't make a full tank a heart attack moment. Its mildly cruiser styled which sets it apart from the CG's RS's and GS's of the small bike world. mine sold for exactly the same as I paid for it after a year of hard riding and 7000 miles.
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Any time you are attempting to "improve" on what the manufacture has produced, there will be time and expense for parts and installation. The first thing to do is to be sure that it is properly tuned to specifications. These bikes require a valve adjustement, clean carburetor passages and jets and a timing check. The bikes are built to be quiet and meet emission control regulations. Once you change/modify the exhaust system (which may or may not help), you risk annoying your neighbors with the racket. Incorking the exhaust system can often bring small benefits, but you are looking at fractions of a horsepower or so, without major expensive modifications. Sometimes, carburetor jetting is on the lean side for emission controls and a change to a next larger main jet and/or raising the needle position in the carburetor slide with a thin washer will help the acceleration. Bear in mind that this engine is only about 7 cubic inches in displacement, hauling 200 plus lbs of machine, plus your own weight, so there is only so much it can do, as it was designed.
You didn't mention mileage on the bike or the year model, so it is hard to say if the bike has some actual performance issues, related to a needed tuneup or it is just the way it is.
Getting more performance generally requires getting more air in and out of the engine... air box mods and exhaust changes. After that, you will have to go into camshaft changes and bigger pistons, if anything like that is available.

Search Suzuki GN125 and see what you can find for any other parts or mods. These are just basic transportation machines, so no one is really making high performance parts for them, especially in the US, if that is where you are.

Bill Silver