99 pedy mountain bike build, need some advice.

Y

young grease monkey

New Member
i am going to start my build in a couple weeks after final exams and vacation the day after finals then i have summer school after i get back from the road trip, 4 OR 8 HOURS A DAY! depends how many classes my parents will force me to take... Anyway, i am thinking about a cvt from AGK. how much wider will it be vs a jack shaft? i am also going to upgrade the back wheel, can anybody suggest a rear disc hub for 7 spd 36 spoke? i will make an adapter to fit the disc brake mount, much stronger than any sprocket adapter that clamps on. also would like to get it machined for cartridge bearings, is this overkill? its only a 99 cc, but I'm thinking of a cvt so...
One more thing; would it be a good idea to tilt the engine forward using a custom mount so i get better access to the valves? or would that place havoc with the oil and carb?
 
Hi Young Grease Monkey,I'm no expert or a moderator but there's a mountian bike section...Try there....But your on the right one as far as I can see,Your going to fab up Your own drive system...a.k.a. DIY....Pictures of the progress are always good,I've figgered out how and have been putting up a lot of stuff that might give You a spark...Many others on here are full of ideas and skills used in the motor on a bicycle game,just look around and take ideas that will help on Your build...good luck!....Tigmaster....
 
young grease monkey said:
how much wider will it be vs a jack shaft?
Click to expand...

I'm working on a similar project, the CVT will add 1-2 inches over a jackshaft/centrifugal clutch.

young grease monkey said:
i am also going to upgrade the back wheel, can anybody suggest a rear disc hub for 7 spd 36 spoke? i will make an adapter to fit the disc brake mount, much stronger than any sprocket adapter that clamps on. also would like to get it machined for cartridge bearings, is this overkill? its only a 99 cc, but I'm thinking of a cvt so...
Click to expand...

I haven't seen any 7 speed 26" wheels with 36h and a disc hub, though there are 8/9 speed wheels that match that config. Sounds like you want to do something like the tophat adapter to adapt the disc hub to a sprocket.



young grease monkey said:
One more thing; would it be a good idea to tilt the engine forward using a custom mount so i get better access to the valves? or would that place havoc with the oil and carb?
Click to expand...

If you have to tilt the engine, a moderate tilt shouldn't be a big deal, you just need to make sure the oil level is correct so the dipper on the crankshaft can still splash oil for lubrication. depending on the frame you may not need any tilt at all.
 
would i need a jackshaft if i am using an AGK cvt? i need to keep the cost down, so maybe temporarily i will put in thicker spokes with the jag joint instead of a sprocket adapter
 
Do some searching in the 4 stroke area for Predator and you'll see plenty of write ups. I have a 99cc Predator sitting in a box in the garage and a CVT, but I don't think I'm going to use the CVT. It robs too much of the top end and limits the speed no matter what gearing you use and yes, you will need a jackshaft in addition to the CVT unless you offset the engine to the one side quite a bit to allow the chain and rear sprocket to line up.

If you want a CVT I have a brand new one in the unopened box that I'll sell you for $90 plus shipping. I hate it when I buy something on impulse and then don't use it and lose money selling it, but some back is better than none.

Roger
 
I just completed my CVT with 99cc Predator build. My conclusions are that after modding the intake with high flow filters, rejetting the carb, and building a nice exhaust, I was able to max out on a flat road at about 33 mph. The acceleration is insane, it will easily pop wheelies, and go up ANY hill you can throw at it. Also the engagement is very smooth compared to a centrifugal clutch, which tend to rattle a little bit at low throttle. I would guess that with a little more work and trying out different springs on the CVT I could get the top speed up to 35 on flat...

I also built a jackshafted 99cc predator build. With that one, the top speed was 43 mph before any intake work or jetting. The acceleration was not as good as that of the CVT build, but it was still better than either a 49cc 4 stroke china engine or a 66cc two stroke.
 
ok, sorry for zombie thread but i need help again. don't want to clutter up my build thread. i'm going to use a belt transmission, and want to use 2 or 3 step pulleys so maybe i can set up a shift mechanism later, but for now i just want to be able to easily change ratios for riding around town or long distance cruising. where can i find step pulleys made of aluminum? mcmaster carr has a good selection of sizes but only made of zinc die cast and 1 hp rated. maybe ebay? they need to be small step though so it isn't a ridiculously wide ratio difference between speeds. any ideas? also i couldn't find a gear calculator that works
 
You must log in or register to reply here.
Back
Top