Chainsaws,weedwhackers,snow blowers...oh my!

Discussion in 'Rack Mounted Engines' started by Guest, Apr 14, 2007.

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  1. SimpleSimon

    SimpleSimon Active Member

    Well, I mounted a piece of tubing on the outer bell cover of a centrifugal clutch once, kind of the hard way. No welder, no power tools at all, and the ID of the tube was about 1/16" smaller than the OD of the bell of the clutch.

    So, I pulled the bell off, and went to the supermarket and bought 2 lbs of dry ice, which I put in my portable cooler with the bell buried in it. While that was cooling down, I heated the tube until it was almost glowing with a propane torch, then (using vice grips and a mallet). I seated the bell inside the expanded tube...

    When everything had reached the same temperature, there was no moving that tube. Period, full stop. Clutch still worked fine, and the angled slots I'd cut in the other end of the tube worked fine to drive the water pump I'd made it for.

  2. muddawg

    muddawg Member

    ok ! srdavos chainsaw bike needed a 25:1 ratio to start from a stand still and is a 42cc engine
    1: if i had an 80cc engine would i still need a 25:1 ratio for the same take off power ?

    2:if i used a trike as a truck to carry me 250lbs and say 120lbs of stuff
    how would that effect the gearing id need

    Last edited: Jul 14, 2008
  3. srdavo

    srdavo Active Member

    are you talking about an 80cc chainsaw or an 80(70)cc bicycle engine...happytime?
  4. muddawg

    muddawg Member

    80cc 2cycle snowblower engine
  5. indiglosk8

    indiglosk8 New Member

    i have a recumbent that i built. me and the bike weigh out to around 225lbs. i want the motor for hil climbing and flat land running. what is the best gear ratio for a 35cc to a 50cc motor?
  6. revelstone

    revelstone Member

    indiglosk8, do you have pics of the 'bent? that would be interesting to see.
  7. Bean4life32

    Bean4life32 New Member

    Stumped on Wacker

    Well I have been looking here for quite some time getting ideas for my project and not i am finally stumped. I have a 25cc craftsman weed wacker engine (no clutch) and I am trying to figure out how to adapt a friction drive to it, the only way to connect to the drive shaft is the square insert. I was wondering if there was anyone who could put in their two cents for ideas on how to adapt a friction drive to that without welding the drive directly onto the drive shaft (so i can change pegs, polyurethane wheels, wood wheels, etc...)?

    I know people have had this problem so i was wondering on getting some tips on home to adapt the wacker to be a friction drive and what others have done

    (Other than welding, have thought of using the cable from the drive part of the wacker, tapping the square insert so that i can put a screw right into the drive???)

    Attached Files:

  8. Happy Valley

    Happy Valley Active Member

    Underneath that case there is a centrifugal clutch. Sometimes they unbolt and sometimes guys open them up and cut them off.

    The 25cc engines usually use the smaller 54mm clutch drum.
  9. a-dam

    a-dam Member

    Pic of my contraption

    Just took some pics of my first project (built it last winter). Would rather be riding it today instead of just photographing it; northern Illinois weather sucks. I just posted this at the schwinn forum, and thought I would share it here.

    I went with the friction drive. It's simple, light, inconspicuous, and completely disengages with the flip of a lever. Tire wear is not an issue at all anymore. I rode almost all of last year on one rear tire. That's about the same wear I got without a motor. My friction drive wheel (scrubber) is made from a hockey puck and steel spacer from Lowes. The "wet weather" scrubber in the photo is made from skateboard wheel with abrasive grit glued to it. Springs pull the unit down onto the tire. It'll bump start at 5mph, no problem. The throttle lever is an old brake lever. I added some extra homemade cable bosses to the frame so the cable runs nice and neat. It's all homemade with hand tools, a bench drill press and disk sander.

    It rides like a Schwinn 10-speed, which I like. I don't go trailblazing with it; mostly ride the country roads within 30 miles or so from home. About 200 mpg - 25 mph top speed. A good pedaling pace in 10th gear... that's about the top speed and I don't want to go any faster!

    Paid $10 for the 25cc Homelite leaf blower at a garage sale. Got the '73 Continental and a chromoly Univega at a yard sale, $20 for the pair.

    Attached Files:

  10. Happy Valley

    Happy Valley Active Member

    That's very clever little setup you've done, I like it, simple and clean.

    Can't see but is there a bearing on the outboard sid of the drive spindle?
    Also, spend another minute or two if ya would telling more how you did the grit thing, and what you used......'preciate it.
  11. a-dam

    a-dam Member

    Thanks HV. You spotted that one right. It's a bearing on the outboard end of the shaft so the motor bearings don't get all the load. Blain's Farm & Fleet sells them for 8 dollars. Here's some new pics to show it better.
    The bearing pillow block is bolted in the black angle which bolts to the "pivot shaft" which runs through mounts on the seat stays of the frame. So the motor and outboard bearing pivot up and down together when I engage/disengage the drive.
    The friction wheel I prefer to use (on the bike now) was made from a hockey puck. A hockey puck is 3" diameter and 1" thick. With hole cutters, I cut out a wheel 1 1/4" inches diameter and drill a 7/8" hole in the center. I can get 3 drive wheels out of one puck, but my first one has lasted a year with little wear.
    So then I epoxied (clear 5-minute epoxy) it onto a steel spacer. I bought the spacer (that's the actual name of the item) from Lowes hardware section. It's 1 1/2" long, 7/8" O.D., 5/8" I.D. and fits over my 5/8" motor shaft. I drilled and tapped two holes for set screws.
    The one that I am holding in the picture (grit wheel) is basically made the same way except the material is a urethane skateboard wheel. Urethane (Gorilla) glue is used to glue the wheel to the spacer and the grit on the wheel. Epoxy don't stick to the urethane good at all, but Gorilla Glue sure does. The grit is from some weird old grinding wheel I got somewhere about 20 years ago. It is "friable"; the grit breaks off of the grinding wheel easily. It is white and rather sharp and glass-like.
    The grit wheel works well in wet weather, but I can notice more tire wear than the dry-weather, hockey puck wheel.

    Attached Files:

  12. Happy Valley

    Happy Valley Active Member

    Excellent pics, my man! Thanks.

    Now I have more questions, hehe.

    So, there is just the one pillow block bearing on the outside then, not one on the engine side?

    Also, I see you've taken some steps I think about....talkin' about the stainless flex. Auto parts store? Lowes plumbing dept? Cut noise much?

    It's a clean setup, small, unobtrusive, tight to the seat tube. Gooder.
  13. a-dam

    a-dam Member

    Yeah, just the one bearing on the end of the shaft. It could work without it, but the "sideways" pressure on the motor shaft would probably wear out the motor bearing quickly. The motor mounts to a 1/8" steel plate. The pivot shaft (3/8" threaded rod) affixes to the plate with nuts. At the other end of the pivot shaft the bearing holder is affixed with nuts. So the whole thing moves as a solid unit. The pull-down springs go from the motor plate to the dropout on the left side, and from the bearing holder to the dropout on the right side.

    The stainless hose is just the braided covering off of a flexible plumbing connector; like you use under a kitchen sink. I used one inside another, that makes it about 90% airtight (which means it is 10% holes - not airtight). It's purpose is really to direct the sooty, oily 2-stroke exhaust out of the "business" area. I wish my motor's exhaust pipe blew out on the left side instead; I wouldn't need that hose. The hose does keep things a LOT cleaner, but I doubt that it makes the motor any quieter at all. BTW, it sounds surprisingly quiet to me. I often cruise past people working in their front yards who don't seem to hear me go by.

    Now that you got me thinking about it, I should just modify the muffler to exhaust on the left. Duh.
  14. a-dam

    a-dam Member

    The stainless covering on the plumbing hose is pretty flimsy; I think it is just for looks. But before I used that stuff, I was out on a ride and saw a long braided hose on the ground; like something off a semi truck. I think it was hydraulic hose. On my way back it was gone. :(
    I think that covering is actually to increase the hoses bursting strength. That stuff (if you can separate it from the inner hose) might work somewhat as a flexible exhaust. I'm totally speculating on that, though.
  15. duste01

    duste01 New Member

    The eccho whackers have one built in
  16. Alaskavan

    Alaskavan Guest

    If the engine dies when you stop the bike, either A. The clutch engages at too low an RPM, or B. There is no cluch.
  17. suitepotato

    suitepotato New Member

    After reading all these ideas, given consideration of modifications to my bike that would in most cases be needed, and modifications to the otherwise useful chainsaw (I have a lot of remodeling scrap to cut up), the idea that comes to mind is to:

    Take advantage of the chainsaw already driving a chain on a solid bar, and... replace the bar with one made for the task of driving a friction drive against the rear tire. With the chainsaw facing to the rear, the chain and anything it directly drives is already facing the right way to drive the wheel by friction. Since metal is somewhat tough on a tire and I use knobby ones, the wheel to drive the bike should be a rubber wheel like a lawnmower wheel.

    It will need a bar made to fit the chainsaw but that should be easily done with my sawzall type saw, and a cordless drill. Maybe a bench broach. The rest of the stuff should be easily gotten at Home Depot except for the drive sprocket but that's no biggie online to find.

    After that some control cabling from a bike shop, metal strapping to rig the control pull on the throttle, so on.

    I'll let you know how this works out when I do it...
  18. Esteban

    Esteban Active Member

    Keep up the posting.. I don't think this thread will ever die !
  19. srdavo

    srdavo Active Member

    Coming SOON.......

    Something NEW......

    from the Garden!!!!

  20. skjjoe

    skjjoe Member

    oh do please tell:juggle: