Manco 706b rebuild

[charford]

Hello everyone,

I am new to the forum, and I recently picked up a well used xtk-706b. It runs pretty well- it has a predator 212cc motor. This will primarily be for my 8 year old to ride. It has 0 brakes currently, so I picked up a new brake kit from GoPowerSports. I also have bought new front tires and a new toque converter from Amazon.

Just reaching out to see if anyone has some ideas on other upgrades I could make or things to look out for when I start going through the thing? I want to replace all the bearings, so wondering which bearings to be looking out for. Also it rides really rough- but maybe that is just because I am 250 lbs. are there upgrades to the suspension I could be looking into?

I thought about upgrading the motor to the predator 420 (because I may want to ride with my kid) however, I think the smaller motor is fine for now until he gets some more experience- I can always replace the motor. Right now it has a hard time getting going with me on it- but I'm hoping the new torque converter could help with that.

Just looking for any good tips and experience to help guide me.

 

[madprofessor]

That missing low end torque is likely more about the gear ratio being too tall for the tire size. Post some pics of the kart all over, count the teeth on your 2 sprockets for us, and measure the rear tire height for us. Lots of experienced folks here to advise you.

 

[charford]

Thanks. I have attached some pictures. The rear tires are 18x9.5-8 about 18-18.5 inches tall. I havent disassembled everything yet but it looks like the drive sprocket is 9 teeth and the driven is 60 teeth.

 

[madprofessor]

60-tooth on the axle's pretty standard, 9-tooth on the CVT is unusual. Usually 12-tooth for #35 chain, 10-tooth for #40/#41 chain.
60:12 would be a 5:1 ratio, but if yours really is only 60:9 that's a 6.67:1 ratio for a much stronger low end and slower top speed.
Don't think the new CVT will change your existing performance, but it does mean a nice new belt, and a new CVT must be better than used.
Don't know why the new bearings are desired, but will give peace of mind and again, new is just better. Also very cheap for the front wheels, and they just punch right out while you're putting the new tires on.
I don't have any experience with those rear hexagonal axles and their bearings, but if the bearings are "sandwiched" between a pair of 2 or 3 hole flangettes, check the websites of the various gokart parts suppliers, GPS, BMI, MFG, GKS, etc.
Front split rims? Means using tube-type tires only for the new tires, solid rims means tubeless tires only, as the bead seat is different. If splits, new tubes are cheap and a very mucho grande good idea, just get the L-shaped valve stems.
That 212 is bone stock. The first mods always give the most return for the costs. Need to toss out the OEM airbox and muffler. Get a high flow air filter and the mounting adapter required for it, just don't get the billet one that's flat on both sides, should be flat on exit side only with a curved venturi on the entry side. A kit with all of it and a choke hold-down lever is the best way to go, because you need it to come with a bigger main jet also. Pretty much a waste without feeding more fuel. Get a header pipe with a screw-on muffler, run w/out muffler wherever you can.

Hope this addresses all the questions you listed above, good luck to you, and keep us updated.

 

[Oldsman]

I redid one of these last year. Rough ride-stock rear springs are 700 in/lbs. Replacement “heavy duty” 450 in/lbs ride much better. Manco single seats don’t help, bottom cushion is thin. Brakes- I eventually went with hydraulic. The mechanical brakes were probably adequate when new, but the amount of wear/slop in the linkage on mine made proper adjustment impossible. (I use a cable to actuate same caliper on a yard cart, another option). A stage 1 kit will make a noticeable performance improvement. If you are changing rear bearings maybe buy a sprocket hub also; 2 piece sprockets are cheap and available in a wide range of sizes/tooth count. I ran a stage 1 212 with a 68 tooth and it climbed hills surprisingly well. GPS isn’t cheap, but they have the biggest selection of 7/8 hex axle parts/Manco parts. Also, awapping a 420 Predator is not a bolt on. Engine mount plate is different, and a bigger torque converter, chain, sprocket are necessary. It can easily turn into a money pit.