Okay, so i got the 42 chainsaw mocked up and test driven. I'll post some pics when i get back to my shop. I have never driven a friction drive let alone anything on 2 wheels less then 600cc, but it was still a fun test ride. Granted i was riding with one hand on the handle bars and one on the Saw throttle.
I still have to mount the pulley setup for the brake lever lift to release the drive from the tire. I used a 7/16 door spring direct from the back of the mount to the bike, Im not sure if it is putting enough pressure onto the wheel but it feels pretty heavy when i lift it by hand and it pushes the roller about 1/8" into the tire. I stretched the spring at a distance i thought was suitable then cut it to length before mounting and bent the last ring to fit through the predrilled hole on my engine mount. I have yet to pick up a turn buckle for fine tuning adjustment.
Anyways, i used a 3/4 nipple for the roller, welded a couple of washers at the end, choppped the original threaded Saw Clutch to fit into the nipple, and welded a nut ontop of it to grab with a socket. Worked out good and its all pretty straight and not lop sided, thats the hard part... Until i dropped it onto the concrete floor and it landed right on the edge of the roller which made it lop sided, DUH! So I tapped it with a hammer on the oppisite side of where it hit the floor and all is straight now.
I took it for a test drive with the smooth nipple so i can get a visual of where the contact point is and if the mount is moving under load. The mount turned out fine but way to much slippage on the roller. i took the roller off and tack welded a bunch of tacks where the contact point is. I can still feel some slippage, not sure if it is from the roller or the spring not being tight enough. The 26x1.95 $20 a piece tires have a smooth street tread in the center and a Knobby tread on the outer edge which the roller doesnt contact. Im going to try another roller with the tacks a little further apart, hopefully it might help with the grab.
Im concerned that using the brake cable to lift the engine might be to much tension on the cable with the tension of the spring.Also, has anyone ever busted a spring?
I didnt have my speedometer setup so i couldn't tell you how fast i was going but i would say a definite 25mph with some slippage on the roller. Im afraid to put more tension on the roller to try and sit tighter on the tire as to the strength of the spring. The engine is 42cc so i know i can get some more kick out of it once the engineering is tweaked right. I did tuned it up the best i could so the rest is down to the mount setup.
Oh yah, I still have to figure out where to mount the gas tank. Yesterday at Sears i saw a 32fl. oz. 40:1 premix round gas can with a plastic screw top for $4.99. prefilled with gas. Its made of thin steel but could be a good reusable tank to use once mounted correctly.
How many Oz. of gas are in a typical weed eater plastic tank and how many estimated miles could one get with the plastic engine tanks or lets say 32fl. oz.?
Sorry so Long...
I'll post some pics in about an hour so check back.