Re: Help me make my Kasea 90 got fast, quickly!
Long time. Just remove the carb restrictor on the carb and it will probably go from about 28mph stock to low-mid 30's. But the power will be there more. Some people remove the snorkel on the airbox. This will lean it out a bit, so you'll probably want a bigger main jet. I've heard that the snorkel almost is up against the tank and could block air-flow and should be cut at a slight angle on the top to help it breathe.
I went to Southwick, Mass to meet a friend I met on the atv source forum. We stayed overnight and went to the races. His daughter has a fully-modded 90 and it was unbelievable these 90cc bikes could be that fast. Her back-up bike only had a few mods on it and was really quick with me on it. It had the Trinity pipe, air cleaner, jetting, clutch and smaller rear 29T sprocket. Would take off nearly as hard as my 400ex and would go a good 45+ mph. You could also remove the oil injection and switch to pre-mix. It will give it a little boost in power and run much cleaner. The smaller rear sprocket would probably be the ticket to get more top-end out of it. But a pipe and clutch work would send it to a whole new level. My son rode the backup 90 that I rode. He's only 5-1/2 and loved it. Now he wants the bigger bike and says he'll give his mini to his little sister ....LOL