Phillybound313
New Member
- Local time
- 5:52 PM
- Joined
- Feb 4, 2019
- Messages
- 12
Hi, new here. Im a welder by trade and succesfully built a friction drive mountain bike using a 79cc predator motor that hinges on the front fork. Almost stock (governer removed, pz19 carb stock and header) with 2 7/8 od black pipe it clocked through speed trap going 36mph on flat. Climbs hills pretty good as well. Ive recently port and polished head(smoothed casting imperfections, smoothed transition top of each bowl near valve guides, and knife edged valve guides in bowl, port gasked matched exhaust and intake, took off .050 using glass and sandpaper (around 10:1 compression), added another spring inside valve springs (about 16-20lb total each spring), welded and drilled new pushrod dimple stock rocker arms to create about a 1:3 ratio (around .220-.230 lift), and filed .036 off flywheel key(around 8 degree timing advance). Im currently drilling stock jet starting with a .80mm #80 jet size in pz19 carb. Im working on that today, thinking around #90-100 or so. Hoping for around 5-6 hp @ 6500-7000 rpm. Also hoping for at least a top mph increase of 5 mph with the added rpm and power without having to increase 2 7/8 od drive spindle.
My newest build is a gc160 motor(5hp stock) and jesse james chopper bike. Ive removed governer, going to use a pz22mm carb, header, and going to increase rocker arm ratio for more lift and added spring in stock springs. Hoping for 6-7hp.
Id like to use a 20 inch rim to make a pulley that will be welded to rear 20 inch rim, and make a clutch using a spring loaded idler pulley in the rear that adds tension to v belt for drive engagement.
My idea and question is regarding the operation and mechanics of a cvt driver pulley.
My idea is to only use a cvt driver pulley that is in the size range of 2-3" for a gear ratio of 10:1 - 6.66:1 with the 20 inch back rim pulley. Since the back idler pulley will be spring loaded, it should keep tension on the belt at all diameters of gear ratio.
Am I understanding the mechanics of the driver of a cvt properly? Doesnt the driver push out and change gear ratio with torque or load output of engine? Doesnt the driven portion of the cvt stall like a centrifugal clutch and stall, or engage at a certain rpm? Is this accurate? If im using an idler pulley to put tension on belt for engagement, do you think this would work?
So far ive found a 1 3/4 inch od driver making the ratio around 11.43:1 ratio which would be just fine. Also, can anyone tell me the approximate od range of a cvt driver? Im hoping it wont exceed too far past 3" or a 6.66:1 ratio. Should be good to 40-50mph. Any ideas?
My newest build is a gc160 motor(5hp stock) and jesse james chopper bike. Ive removed governer, going to use a pz22mm carb, header, and going to increase rocker arm ratio for more lift and added spring in stock springs. Hoping for 6-7hp.
Id like to use a 20 inch rim to make a pulley that will be welded to rear 20 inch rim, and make a clutch using a spring loaded idler pulley in the rear that adds tension to v belt for drive engagement.
My idea and question is regarding the operation and mechanics of a cvt driver pulley.
My idea is to only use a cvt driver pulley that is in the size range of 2-3" for a gear ratio of 10:1 - 6.66:1 with the 20 inch back rim pulley. Since the back idler pulley will be spring loaded, it should keep tension on the belt at all diameters of gear ratio.
Am I understanding the mechanics of the driver of a cvt properly? Doesnt the driver push out and change gear ratio with torque or load output of engine? Doesnt the driven portion of the cvt stall like a centrifugal clutch and stall, or engage at a certain rpm? Is this accurate? If im using an idler pulley to put tension on belt for engagement, do you think this would work?
So far ive found a 1 3/4 inch od driver making the ratio around 11.43:1 ratio which would be just fine. Also, can anyone tell me the approximate od range of a cvt driver? Im hoping it wont exceed too far past 3" or a 6.66:1 ratio. Should be good to 40-50mph. Any ideas?