New here, with a DIY Chainsaw Bike

Discussion in 'Introduce Yourself' started by Lightning Boy, Apr 19, 2014.

  1. Lightning Boy

    Lightning Boy New Member

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    Hello fellow builder/riders! First, I'd like to thank everyone here at the forum for their helpful posts. This bike would have taken a lot longer without the tips I've found here. Deacon, thank you especially. (I hope this thread finds you in relatively good health and spirits.) Long story short, the information found here is a blessing for noobs like me.

    Let's get down to business: I used the engine from an old chainsaw/ tree shaker? of unknown origin, and mounted the casing directly to scrap steel mounting brackets. The bike is my trusty old Huffy Diesel BMX from 1999 or so. The frame is more solid than most 20" bikes, and I wasn't easy on it as a teenager- so I trust it will hold up well. I wanted a drive that could bolt on and off without welds on the frame, so I would have the option of restoring it to stock in the future in case something went incredibly wrong. I'm a small framed fellow, maybe 140 if I'm lucky- so this mystery motor should have enough push to get me around at a good pace...

    The brackets were just a matter of bending the steel and measuring/drilling holes for the axle and engine supports. The two beams on each side and the one coming off the seat are all connected by support brackets and the engine. The tensioner is a U-bolt through the saw handle and around the seat bracket. When I need more grip, I tighten the nuts. If you're brave enough, you can adjust it on the move with your right hand.

    For the engine, I removed the clutch and bell, then cut small angled grooves in the clutch bell with a grinder for traction. Then, I reconstructed the clutch housing. After that, it was all nuts, bolts, locking washers, and loctite. I did have to tap the holes on the saw's casing a little larger, as I didn't trust the small threads and bolts under all the stress. It sits directly on the back wheel.

    Once I got some forward motion from the engine, I figured it was a good idea to put some lights on this beast. The control panel box was recycled from a broken minnow aerator pump, and I power all lights from an 18v rechargeable drill battery mounted under the seat, on the frame. There are head, brake, tail, and L/R turn lights. The turn lights are on momentary switches, so you can blink them manually and not worry about leaving one on. The other two switches are just your standard on/off Single throw type, and they control the brake light and head light. When battery is connected, the tail/run light stays lit. All wires came from wall wart transformers I gutted for a separate electronics project. Pretty much everything I used was already laying around in the garage, with the exception of the old moped headlight from my Grandad's backyard junk pile. The tail/brake light was a broken tail/turn recycled from Dad's fishing boat. The turn signals are purple LED circles, mounted on each side of the back wheel on the mounting brackets. They're attached with Industrial Velcro. Just some extra stuff I had in the electronics tackle box that saved me from soldering up a few LED strips. I didn't need turn signals really, just wanted them for a nice touch. (Lights are off in this first pic, so you can see everything else.)

    The first few rides, I was using lighter supports on the side brackets. They were made from an old car amplifier chassis and a reworked steel coin tray for a vending machine of some sort (little bro was making them at work, and he gave me one from the scrap box). That worked great, until the mounting tabs I drilled snapped clean off. Luckily, the rest of the engine frame kept me away from a disaster... After that, I decided to go the overkill route. The steel I ended up using is pretty stout stuff, with a plate twice as thick on the non-engine side to help with balance.

    The tricky part was keeping both hand brakes, while still having a relatively comfortable throttle system. I ended up going with a gas pedal-like system, with a lawn mower throttle cable through the trigger of the saw. The cable goes through a hole in the bottom of the pedal plate, straight back around the outside of the saw to the trigger. There is a small spring connected to a bungee cord on the end of the top dropout tube to help bring the throttle back with the extra weight. The pedal was made from a random plate bracket (that looks similar to a hinge) and a solid support rod that already had the proper angled tabs for the right fit. I have no idea what they used to be, but turned out perfect for my purposes. Finding them was sheer dumb luck, and the pedal clears the front wheel nicely. I don't think I'll be needing full throttle through the turns anyway. I used coated down-rigging cable for the first couple days, but it breaks religiously... Should have went with the brake/throttle cable from the jump. There's a good reason everyone else is using them. The donor lawn mower with a bent shaft supplied the cable and muffler.

    That muffler is a whole separate can of worms. It took a few tries to get that one right. This old saw has a torqued rectangular flange on the exhaust port for the stock spark arrestor and exhaust tip, and it wouldn't come off for anything. So, I just decided to bolt a soup can to it, and tap the bottom of the can for the muffler. That worked for about 2 days, until it sheared through the bottom around the mounting bolts. I cut away the sheared bottom, leaving a sleeve- then put a spam can over that with a hose clamp in the same fashion (to putt around until I came up with something better).Then, I bent up a lid/cap from some thin (yet much thicker than the soup can) steel plate to connect the sleeve of the remaining can (which I'd already formed to fit around the tire and clutch bell) with the muffler. I used the muffler bolts on the wall side and the hose clamp to secure it to the sleeve. It's a screwy looking thing, but it works well so far and doesn't vibrate. I've got a week or so of short daily trips without any problems now, but I spent a couple weekends working out the various weak points in my engineering. Now that the exhaust has stopped falling off, I might try a longer stroll in the near future.

    Note: The plastic gas tank under the seat is only a reserve, not connected to the saw tank in any way. The lines you see only go under the seat so as to be unobtrusive while keeping the vent line and fuel filter intact. Just gives me a bit more distance, should I need it. It's secured by a bungee connected to my chain/lock on the seat post, and thick rubber bands found on veggies, with a foam pad between it and the seat post/cord hooks.

    There's a small fender on the back made from a monster can, and one on the front from the doomed spam can. Put them on after getting caught in the rain on it and soaking my legs and hind parts. Surprisingly enough, it will run in the rain. Just stay away from the puddles! I'm sure that is helped by the aforementioned grooves I cut in the clutch bell for traction. Wouldn't work well with a smooth bell, I imagine.

    It's not as pretty as it probably could be, but functionality first.

    I've got a few more pics of it, but having a hard time getting them to upload. They're on the way soon, though.

    Again, thanks for all the help! I'm sure there would have been much more time wasted and many lessons learned the hard way without the members of this inventive forum!

    .cs.
     

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    #1 Lightning Boy, Apr 19, 2014
    Last edited: May 24, 2014
  2. Lightning Boy

    Lightning Boy New Member

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    Here's the front end. I guess I can only add one pic per post. Every time I try to add more than one, it just replaces the first... Bear with me, folks. I'll get it. :)
     

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  3. Lightning Boy

    Lightning Boy New Member

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    Another view.
     

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  4. silverbear

    silverbear The Boy Who Never Grew Up

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    Welcome to the forum... looks like you have no trouble thinking outside the box and being resourceful in using what you've got.
    Regarding the photos you should be able to load five at a time.
    Had to ask about your forum name since I'm a lightning survivor, having been struck in 1995.
    SB
     
  5. Lightning Boy

    Lightning Boy New Member

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    Thanks much, SilverBear. It all starts with a good idea. Forgot to mention that I drag start it now all the time, since the recoil spring snapped while trying to reattach the cable. I've built a lot of random stuff, but this was my first bike build. Quite an adventure. I've had this engine kicking around for years, but only got around to fabricating it onto something recently. Just as much fun to ride as my "proper" motorcycle.
    About the name: I actually stole it from the protagonist of the '80s guitar movie "Crossroads", as it relates to my love of music and electronics. I normally build amps from junk alarm clocks and stereos, guitar effects, or something else electrically powered and/or guitar related. No experience with that many volts, or anything even close. Anyone who has is a friend of mine.
     
  6. Dan

    Dan Staff
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    Uber cool, LB!

    Love the down & dirty, DIY look.
     
  7. Lightning Boy

    Lightning Boy New Member

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    Thank you kindly, Dan! The distance run today was a success. Got me halfway across town, no problem. First time I actually needed the reserve tank, but I may eventually replace it with an aluminum water bottle for even longer trips. Really digging this new toy. :)

    r.ly.
     
  8. 2strokebke

    2strokebke New Member

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    Nice saw bike
     
  9. Bearded War Machine

    Bearded War Machine New Member

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    I have to say. I really dig that airhorn. Nice build and welcome!
     
  10. Lightning Boy

    Lightning Boy New Member

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    Thank you, BWM! Glad you like it. Seemed like the easiest, most effective way of getting a noisemaker up front. Just a little insurance in case they don't hear the exhaust. I wanted to be as street legal as I could possibly be on a friction drive chainsaw bike, and it just happened to match the color and look.

    On the topic of street legal: No trouble from local law so far, and I've seen a bunch. However, I ride respectfully on the shoulder/far right, never on the sidewalk, and give a wave when I see them. I haven't registered it yet either, but I plan to attempt it (as brave as that may sound). Not sure how they're going to take that at the Secretary of State office, but worth a shot. :)

    As it's starting to rain in my neck of the woods, time to park the Diesel for a bit. Helping my Stepdad with an OCC Schwinn Flying Horse build as I type this. Looks like he caught the bug again... He first had the engine on a Huffy cruiser, but hated the jumpy chain tensioner and high ride. Hopefully this one will suit him better. Maybe a pic or two of that on the way.


    brnot
     
  11. Lightning Boy

    Lightning Boy New Member

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    After looking at it a while, I figured I could come up with something better for my front fender. The gold Spam can didn't look quite right with all the chrome anyway, and didn't deflect as much water as I'd like. Not that I ride in the rain a lot, but it tends to sneak up on you around here. Also, it's less mud I'll have to clean off before I bring it inside. I found a scrap piece of stovepipe kicking around, so I bent it to form around the wheel. Then, I cut some brackets of the same material, folded over a couple times for strength. I think it looks better, and is definitely more effective than the first. I could have bought a nice one, but the basic idea with this build was to make what I need from what I have. As I ride around and collect more things in my backpack, I'm sure there will be other alterations as well.
     

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  12. paul

    paul Active Member

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    great looking motorized bicycle, looks like a lot of planning went into your build, great to have you with us
     
  13. Lightning Boy

    Lightning Boy New Member

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    Thank you, Paul. I did plan a lot of it before I started, but a few things were decided either by necessity or readily available materials. It turned out better than expected, though.

    I had a mechanical failure tonight, partly my own fault. The grooves were a little too pronounced in the clutch bell, and two of the "teeth" broke clean off on my way home. Luckily, I was close enough to limp it home under a feathered throttle and pedal assist; with no grave damage to my tire.

    I decided this was a good time to cut the clutch collar nut from the assembly and try a new drive wheel. Still no reverse nuts to be found around here, so I was already thinking ahead on it.
    Using one of the pegs removed from the back tire at the moment, just for simplicity's sake. (I also cut some oak roller blanks with a center drill hole saw in anticipation of this, but I'll wait to finish them until successfully testing a peg.) I used a cutting wheel to separate the nut from the clutch pivots, and make an octagon (stop sign) shape from the diamond-shaped collar plate surrounding it. This locks in flush and center with the peg, and attaches just the same as it used to. There is a tight fit washer between the back of the peg and the shaft to prevent slip and wobble. No play in them whatsoever. Pleasantly surprised how well the concept turned out. Might just leave it this way and start on an assortment of pegs... After a short test run, I realize now how much power I was losing with the smaller surface area of the clutch bell. I wish I would have just done this in the first place. However, I didn't want to chop it down until absolutely necessary. Night and day difference now- in the best way. :)

    I was too caught up in the bike being sans engine to think about taking a pic, but I'll try to get one of the fastener inside the tube. Kicking myself for that one. I'm sure someone else has had this problem, so maybe the idea will be of use to others with no other option.
     
    #13 Lightning Boy, Apr 24, 2014
    Last edited: Apr 24, 2014
  14. Lightning Boy

    Lightning Boy New Member

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    It was hard to get the proper angle with the lighting, but you get the idea. Here's what it looks like inside the peg drive:
     

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  15. floridaboy

    floridaboy New Member

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    Lightning Boy, That sure was using your head to make that nut shaped piece out of the clutch part. I could not find a bike peg laying around but found a 7/8 3/8 drive deep well socket works good grind some lines in it.
     
  16. Lightning Boy

    Lightning Boy New Member

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    Thanks, Florida Boy. It was the simple and cost effective way to do it in-house without paying a ridiculous price for a nut. Couldn't justify paying an arm and a leg for a part on a bike I built for free...
    I was just thinking about grinding some traction into the peg, too. I'm in the process of making a bunch of different peg "treads". Already made a wet weather Paddle wheel from vacuum belt interlocked and enclosed in duct tape. The wrap is such that it tightens as the wheel spins, much like a reverse nut. Haven't tested it yet, but seems good in theory. I plan to make one with a checker/knurled pattern and one with lines down the length of the peg and compare results. The ones with the threads outside didn't sit very well, and cut grooves more than it pushed. The stock pegs that were on the bike are actually a small bit larger outside diameter and fit my driveshaft better. I thought about tossing a 1 1/4" or 1 1/2" socket on, but both were considerably heavier. Thanks for the tip.
     
  17. Lightning Boy

    Lightning Boy New Member

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    Just tested the peg with cut grooves down the length every 1/2" or so, and it worked fantastically. All grip and no slip, requiring much less tension on the U-bolt. Kept up with the chain drive Chopper easily without pedaling at all. Easier to start, too. Only took a couple kicks. Dialing in to be a nice little ride.

    cvlt1
     
  18. Dan

    Dan Staff
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    Really cool thought and TY, LB. Looking out for others and offering the benefit of your work and experience.

    Some really great folks here and your one of em.

    http://motorbicycling.com/showthread.php?t=77
     
  19. Lightning Boy

    Lightning Boy New Member

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    Thanks again, Dan! Just doing my part to contribute to the archives. I'd never seen that particular issue addressed before, so hopefully it saves someone else some time brainstorming a solution.
     
  20. rustycase

    rustycase Gutter Rider

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    Great thread, LB!
    You've done a good job.
    :)
    rc
     

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