Honda GX-160 Extra Long Mike

Discussion in 'Photos & Bicycle Builds' started by MikeJ, Jun 25, 2011.

  1. MikeJ

    MikeJ Member

    Honda GX-160 Extra Long Bike

    Attached should be photos of my bike. The most complete part that I have not taken apart, modified, bolted on, discarded, improved, or taped on is the one-piece basic frame. It came welded together.

    Parts were gathered over time over many different purchases. I know because I have all the receipts.

    My extra-long bike does run as you see it. But even as I write, it is being updated with a modified exhaust system and modified intake system to take those items out of the interference path of my legs when I pedal.

    Last night, I changed out the quick-release hollow axle for a stainless steel solid axle and add-on chain tensioners. Now the rear wheel cannot shift sideways during hard acceleration.

    As a side note (in reality, call it a gripe), when I took my wheel to two separate bike shops, the unimaginative wrenchers himmed and hawed and made up excuses why the axle swap could not be done: they don't know the thread pitch, they don't know the axle diameter, they may not have parts, yadda, yadda, yadda. (All they saw was the rear wheel.) I asked if they had some spare axles laying around. (Now they were visibly angry at me.) The showed me a box of used and new axles; I found a good one within 15 seconds, saw it was undamaged and bought it for $12 and took it home.

    Once I started, the axle swap took about an hour while I was taking my time, studying how it was assembled. The wrenchers wanted $60 to "try". Poo on them. I can swap out axles under an hour now and can be assured it will work as good as factory new. In my case, better.

    You can see a hint of tail lights. The basket holds a 12V sealed lead acid battery to power them. The handlebars hold three multi-LED headlights. I also wear a reflective vest and helmet. Drivers just move away from me as they pass.

    Tires are puncture resistant "tire within a tire".

    Disk brakes are an absolute must for me.

    The seat is wide and comfy. This seat has over 1500 miles on it.

    The very wide pedal shaft was necessary; from a bike parts vendor.

    The 163cc Honda engine (no governor, performance cam, no oil sensor) is overkill.

    The wooden engine platform is strong red oak. It is the only one in the world as far as I know. It will easily withstand engine torque.

    The 5/8 inch diameter jackshaft uses two cast iron industrial pillow block bearings; overkill here.

    Front shocks replaced solid forks.

    Handlebar was custom selected from a local bike shop.

    The extension was the back half of another mountain bike.

    The motorcycle helmet is mandatory; I won't ride without it.

    The centrifugal clutch is an improved version over a factory copy.

    Have to run.... Just got another idea......


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    Last edited: Jun 25, 2011

  2. oldguy387

    oldguy387 Member

    Now that is a head turner! Dale
  3. MikeJ

    MikeJ Member

    Yes, a few people have looked at it and wondered, "What is that thing?".

    Attached should be the latest photos. I rode it for a while last night. It would qualify as a cross-country machine. For now, I will use it for long-haul (more than 50 miles) rides on weekends and short rides during the week.

    With that much horsepower, I may have to stiffen that long frame with some added tubing along the horizontal dropout arms. I can feel the frame just not rock-solid stiff as a short frame feels; it flexes a little bit.

    I have not collected mpg numbers. With this 160 cc engine, I am anticipating 80 mpg. Get-Up-And-Go power needs fuel to make that happen. . . .

    The first photo shows a newly-welded and cleaned-up exhaust manifold. Now there is little chance of getting leg burn. But the heat it throws off is still too hot.

    The second photo shows the entire exhaust system in place. It is reasonably quiet. With this big horsepower engine, I don't need to open the throttle much to make speed.

    The third photo shows an overhead shot of intake and exhaust before modification. Note how wide this is. Combined, both functions interfere with leg pedaling.

    The fourth photo show an overhead shot of intake and exhaust after modification. Note the more narrow profile. Now, neither function interferes with leg pedaling.

    The fifth photo shows the bike after a 10-mile run at only break-in speeds.

    The last photo shows the modified intake system. The flexible hose length came from the new upright vacuum cleaner. (So far, nobody except me has noticed the cleaning hose is a bit shorter than expected.) The white parts are plumbing PVC pipe parts from Home Depot. A 1 1/4 inch hole saw and some elbow fittings and some PVC cement makes assembly pretty easy. The aluminum part next to the carb is from AffordableGoKarts. It was a perfectly good part; I cut the thickness down using a hacksaw and sandpaper to suit my needs.

    Next, I will make the brake lights and headlights more functional. Like any other little improvement, it entails a few steps and an hour or two here and there.


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  4. cpuaid

    cpuaid Member

    i have to second that gripe about the LBS not wanting to work on a bike because it was "motorized". i also wanted to replace my quick release skewer with a solid axle on a Diamondback MTB but they were very uncooperative when they saw that it was to go on a motorized bike. thanks for the pics on your build, you've taken thinking outside the box to another level. congrats on a very unique build!
  5. professor

    professor Active Member

    Mike, I am remembering that initially you wanted to have the back full suspended but ran into issues.
    Looking at the bike, I was thinking if you dropped the chain down with an idler to a location just AT or UNDER the pivot point of the rear section- that the rear would be able to go up and down to follow bumps (full sus. mode) and the chain would stay on.

    I am using a suspension seat post along with the cloud 9 seat, but there is no comparison to a full suspension deal.
    Just thinking out loud about how to get away with the suspension rear.
    I THINK it would work.
  6. MikeJ

    MikeJ Member

    Hi Professor -

    Your idea will work. My original non-motorized build had a single motorscooter shock absorber between the front seat tube and the rear seat tube. Without an engine, that articulating design worked great. I felt no chain loosing nor tightening when the rear section bobbed up or down. If it did, my legs of a frail human absorbed the slacking and tightening.

    With an engine, the sudden tightening of the chain may be too much for too many times. I have casually noted motorcycle designs since I wanted to try the rear shock absorber idea. And I don't recall seeing a brand-name cycle where the rear wheel and engine are are on two separate planes. Both are bolted to the same frame members that will not flex. With all their R&D money and time, the big name motorcycle engineers probably have a good reason for their design of an engine and wheel unable to move relative to each other. My guess is this flexing concept proves to be destructive after a limited number of flex cycles.

    Your idea will work IF there is compensation built in. . . like some kind of idler gear that can move, taking up slack as the rear wheel moves one direction and providing strain relief to the rear sprocket by allowing chain slack when the wheel moves the other direction. Getting the idler adjusted just right would be a matter of trial and error.

    I am betting that is why the big motorcycle maker lock the engine and rear wheel to the same plane and isolating the rider with shock absorbers. Maybe you have seen small 1950's Farmall tractors with their steel seats on a single leaf-spring arm. I used to drive one. Small vertical jolts did not hurt the behind section of the driver. I have seen a very few motored bicycles built with that design. Those seats are probably pretty comfortable. . . .

  7. motorpsycho

    motorpsycho Active Member

    ummm, is that a 2 peice wooden engine mount that's bolted together and held to the frame with j.b. weld?
    Last edited: Jul 5, 2011
  8. MikeJ

    MikeJ Member

    Easy there, Motorpsycho. . . You are observant. You make it sound like building with wood is a gross lapse of engineering judgement. Not always, and certainly not in this build.

    That block of wood is seven laminations of hard red oak, glued together like plywood with glue that is stronger than the wood itself. (You thought pine? Surely you jest; not even a remote contender for this purpose!)

    The bolts you see are purposely close to the down tube and seat tube and squeezed the tubes upon tightening. The JB Weld is a gap filler. The tube areas to hold the block were sanded down to bare metal with 60-grit sandpaper. I washed the bare metal with MEK to clean off any skin oil and left the rough scratches in the tube surface. It took me 5 sets of that sticky JB Weld stuff to fill in voids and build up the fillets you see. Admittedly, this is not the strength of a hot stick weld, but for this purpose, it does just fine.

    The block is 2 5/8 inches thick, 5 1/4 inches across, and 21 inches long. The engine base holes are corners of a rectangle of 6 inches by 3 inches. The engine does not rock and cannot slide in any direction. The area covered by the 1.5 inch diameter chromoly steel tubes is many square inches of holding surface. When fully loaded, tube twisting is imperceptable. I'm sure it is there, but I know it is a whole lot less than by a 66 cc HT engine I have on another mountain bike with the engine mounts

    I once computed that the previous engine, a HF 2.5 HP 4-cycle, would put out a max of 300 inch-pounds of torque. Though not an exacting correlation, the tensile strength of this red oak is 9000 pounds per square inch. I am comfortable with this strength margin.

    That block of oak is also holding an industrial strength jackshaft arrangement. It needs gross abuse to fail.

    If I had to select any one item that is the weakest link in this setup, I would choose the chain that runs between rear wheel and bottom bracket sprocket. I have not found a tensile breaking point of that chain; I have 1,000 pounds in my mind for some reason. Oh, well. If one link fails and the entire chain does not spontaneously fall apart into a thousand pieces, I simply pull out my chain breaker (everybody carries one, right?) and simply splice the chain back together and ride again until another link fails. Then repeat the fix. Maybe replace the chain with a new one when I get back.

    Life is good when you can ride a one-only model of anything with high confidence it will stay together for many rides to come.

    Thanks for writing!
    Dankoozy likes this.
  9. buzbikebklyn1

    buzbikebklyn1 New Member

    I salute your ingenuity...
    The "use what you got" ideal, shes a bit clunky looking but I bet she hauls the freight...
    Nice job...
  10. professor

    professor Active Member

    Mike you have a great attitude. The motorcycle makers keep the pivot point for the swingarm in line with the output sprocket so as it swings- the arc it makes affects the chain tension very little.
    My suggestion of putting an idler below or preferably at that pivot point would keep the top chain's distance to each sprocket the same as the rear moves up and down. The lower section of the chain already has a a tensioner of sorts in the gear selector mechanisim. The top chain would have a V shape to it, so the idler would keep the chain down at that pivot point.
    I would like to do a full suspension bike next, so my mind has been on design.
  11. MikeJ

    MikeJ Member

    Hi Buzbikebklyn -

    Yes, thanks, my bike does haul the "freight". If I placed this "freight" on a non-motorized bicycle, I would have to pedal about 325 hours or close to 5,000 miles to dissipate it.

    I think I will motor the distance instead. Maybe do as some impressive builders have done and cruise through multiple states and finish the day with a big smile . . . .

  12. buzbikebklyn1

    buzbikebklyn1 New Member

    I still like the laminated red oak motor mount plate.
    Did you fab it up using some kind of epoxy and clamps?
    If I might point out a few ideas?
    Since its wood why not shape it a bit more sleek looking?
    Paint it perhaps?
    It might save on having to explain your choice of wood all the time.
    Just my 2 cents worth.
    Great job.
  13. buzbikebklyn1

    buzbikebklyn1 New Member

    I'll third that comment, I've found that many bike shops refuse to work on moto bikes... some kind of "bicycle purist" nonsense...
    I guess that why we need the forums.
  14. TREEWK

    TREEWK Member

    Have Only Went To One Local Shop A Couple Yrs Ago. They Have 2 Or 3 Stores Here. I Was Treated Normal, Very Well. Bought Some Used Bicycle Tools From The Mechanic.

    He Came Out To My Truck And Got A Kick Out Of The Motor Bike. He Searched Thru The Dumpster And Found Me A Nice Front Suspension Fork.

    That Is My Only Experience At A Lbs.

  15. geebt48cc

    geebt48cc Member

    Gosh, I bet that bike, on nice level ground ,would out-run these 66cc China wonders? Uno, if the conditions were just right?

  16. MikeJ

    MikeJ Member

    Hi Guys -

    Treewk - You just keep on texting any which way you need to see what you post. We can all overlook whatever compensation is necessary to deal with deteriorating eyesight. We may all be in your shoes someday.

    Geebt48cc - Would this bike outrun a 66 cc? Well, in the right hands, it better! The Honda stock 163 cc engine has been dyno'd at 4.8 HP at 3600 rpm. This particular engine has a up-performanced cam, brag, brag, and more brag. Now, on top of that, which I never mentioned anywhere before, is the larger V-pulley, which I can swap out in literally seconds with different diameter pulleys. The result? If I drop the 9 inch pulley down to a 6 inch pulley, my speed loping along at 4000 rpm in second gear jumps from 31 mph to 46 mph. A small wind resistance guy should be able to maintain that. (All this is based upon spreadsheet calculations. If I ever reach 40 mph at any time, it will be unintentional or there is a bear behind me and closing in. Then I will push the throttle to wide-open...)

    Talk at you later!
  17. TREEWK

    TREEWK Member

    Thanks Guy`s

    I Must Be Getting Too Touchy These Days!! Inside Too Much, Hot Weather.

    Nabor Kids Are Upset About The Demise Of The Local Ice Creme Truck.

    I`m Thinking Spell Check Is Artificial Intelligence, But Will Stay With It For A Bit Longer. Need A New Keyboard, This Old One Makes Way To Many Grammer Mistakes . I Never Aspired To Be A Grammarian. Seems It Would Be Handy Here.


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