Fox Campus Trail Bike Build

Alternative- to increase your gear ratio (make the bike lower geared) you can increase the number of teeth (diameter) of your jack shaft "input" sprocket. That is the sprocket connected to the clutch. Or, you can decrease the jack shaft out put sprocket- the sprocket driving your rear wheel. From the photos, it looks like your output sprocket is pretty small.'

Both of those actions require chain adjustment, and quite possibly adding or subtracting chain links. If you have that tool, it is a very easy job to do. I would rather do all of that, then pull the rear wheel off and deal with changing the rear sprocket, if I were a guy just starting out with these. (simplicity)

One tooth can make a big difference. Glad to see you got it up and running.
Thanks for the input. The output sprocket on my jackshaft has 14 teeth. The hope is to eventually forgo the clutch and attach a cvt in its place. The more I dig into it I'll find out if that will work how I'm expecting. Would like larger diameter tires to allow for more ground clearance. That was a big limiting factor on the camping trip. Always open to suggestions to improve the bike.
Got the base rough cut today. Still need to round the edges and drill the holes for the T-nuts. Then just paint to seal it and off to the upholstery stop. 20181209_134817.jpg 20181209_134839.jpg 20181209_134805.jpg
Got the old mini bike out the other day for the first spring cruise around the yard. Coming up my hill the clutch started slipping really bad. I'm thinking it is torque converter time! :D My only concern is if I can get the sprockets to line up with my jackshaft. Not a lot of room to move the engine around in the frame. The 212 is a little big for the campus frame.
Now that it is warmer out again. I've hopped back on working on the seat for the mini bike. It's taken me way too long to get to this point for this simple of an item, but I'm pushing forward once more. Trying to stay focused. Ha ha


The seat base fits well. I just need to put a fillet on the bottom edge of the base so it doesn't want to cut into the cover over the years. I also finally got around to making my cardboard wheel mockup. I want to put larger wheels on the bike but was concerned about clearance to the frame in the front with suspension travel. I will have roughly two inches of clearance to the larger wheel and tire. And rounghly 1 inch of clearance with the front suspension compressed. Now I can sleep easy ordering the larger wheels and tires. Ha ha :D


Tonight got the bottom edge rounded and just for fun slipped the cover on to see what it will look like when finished. Next paint the base to seal it and then finish it up.

20190513_184900.jpg 20190513_184908.jpg
2019-05-13_19.21.29.jpg 2019-05-13_19.22.16.jpg
Got a little paint on the seat base to seal the wood last week. My new wheels came for the mini bike tonight. The wheels were bolt on with just a little math to properly cut the bushings for the rear to align the sprocket to the jackshaft and center the wheel. I need a longer chain due to the new larger sprocket. The project is really coming together and I'm getting pretty excited. :D Need to call the upholstery shop to finish up the seat. Still more to come. Stay tuned...

2019-05-21_20.47.34.jpg 20190521_173736.jpg 2019-05-21_20.48.09.jpg
2019-05-21_20.48.49.jpg 20190521_200507.jpg 20190521_200711.jpg
20190521_200721.jpg 2019-05-21_20.49.33.jpg
Hitting a minor speed bump in the project. I'm trying to figure out how the factory drum brake would have worked, but without any of the clues being present. I know the bike had a drum from the factory based on pictures, but mine is long gone. I'm currently running a band brake but need to figure out an alternative brake if I'm to use the torque converter. Also struggling to see how the chain tension was adjusted on the factory set up. If anyone on the forum could help shed some light on these mysteries it would be much appreciated.
Here is what my swing arm looks like. The previous owner was using the L brackets to prevent the axel from moving forward and control chain tension. If anyone has any ideas it would be much appreciated.
20190529_190132.jpg 20190529_192505.jpg
Guessing everyone on the site is as stumped as I am, on the factory chain tension/rear brake set up for the Campus. I guess I'll put the drum brake on the back burner for now. I will need to get it figured out at some point so I can use my Chinese tav30...

In the meantime my new clutch and longer chain came in the mail last week. Finally got around to putting the new parts on the bike last night. I also switched the input and output sprockets on my jackshaft. That was a major improvement coupled with the 72 tooth sprocket on the rear. Turned the old campus into a wheelie machine if you aren't easy on the throttle. Zipped around the yard some last night, but still am waiting on the seat to be done at the upholstery shop. Hoping it will be done next week.
Picked up the seat from the upholstery shop today after work. And and I mean I knew it would make a difference, but WOW. I love it! Just need to keep making progress. Though I'll probably just enjoy the old mini bike in its current state for a little while.