I've been restoring a 1971 Suzuki TC120 over the last year and I'm at the point now where I can almost call the project complete, except for one remaining issue. The top speed for my bike should be around 65mph, and I was able to hit about 70 mph without issue at the end of last fall before I did some additional work on the bike over the winter. Overall the bike is running great now, the only problem is that the speed is topping out at right around 50mph on flat ground, WOT, which is consideraly slower than the top speeds I was getting previously.
I guess at this point it seems like the likely culprits would be that the current top speed is limited by the size of the main jet in the carb, and at about 50mph its sucking in all the fuel it can get with the current jet size, and I'd need to increase the size to increase the top speed. Another possibility could be clutch/3rd gear issues, but I haven't really done any clutch/transmission work yet so I'm not familiar with troubleshooting those issues. Overall though I haven't noticed any issues with the clutch sticking/slipping, trouble shifting to certain gears, etc. I've also checked some of the other basic things that could impact speed like tire pressure, chain slack, etc.
Does it sound like I'm on the right track by looking at my main jet first, or is there anything else I'm missing?
I guess at this point it seems like the likely culprits would be that the current top speed is limited by the size of the main jet in the carb, and at about 50mph its sucking in all the fuel it can get with the current jet size, and I'd need to increase the size to increase the top speed. Another possibility could be clutch/3rd gear issues, but I haven't really done any clutch/transmission work yet so I'm not familiar with troubleshooting those issues. Overall though I haven't noticed any issues with the clutch sticking/slipping, trouble shifting to certain gears, etc. I've also checked some of the other basic things that could impact speed like tire pressure, chain slack, etc.
Does it sound like I'm on the right track by looking at my main jet first, or is there anything else I'm missing?
