HP Pocket Bike Engine On Friction Drive

Discussion in 'Friction Drive' started by 5-7HEAVEN, Sep 14, 2009.

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  1. 5-7HEAVEN

    5-7HEAVEN Guest

    When I wrapped up the "GP460 Engine On Friction Drive" project, I expected "The Iron Dragon", a short Giant Rincon bike to be a dependable commuter bike, despite its lack of low end torque.

    Unfortunately, two days later the 460 engine again chewed up its clutch springs enroute to work. Instead of buying more springs, I ordered an adjustable pocketbike clutch for this GP460 and a entirely different drive system. Everything will be bolted onto a second bike, a much taller Diamondback Response MB. So I removed the 460 engine from "The Iron Dragon"...

    and installed a high-performance pocket bike engine in its place. :devilish:

    This was something I had purchased on ebay two years ago and placed onto the shelf. The seller claimed he had dyno sheets proving that the engine made 10hp.

    I'll be happy with 5 HP.:whistling:

    Anyway, the pb engine bolted onto the existing components of "The Iron Dragon" with minimal changes. BMP friction drive engine housing, fuel lines, goped tank, 1.375" Staton friction roller. Even the ADA pipe bolted on, but at a different angle. The exhaust flange's bolt holes were enlarged to accept the pb engine's port.

    I had some difficulty hooking up the throttle. The previous owner installed a Walbro carb and fabbed his own throttle cable guide slightly off kilter. The cable feels very stiff, so I may need to make a smoother throttle system.

    I just need to order or make an exhaust gasket for the engine. It should be ready to fire up tomorrow.

    I've got a feeling that this engine will have a LOT more low end TQ than my GP460 engine. Using the existing 1.375" roller, I should hit 35mph at 9700rpm.

    Time will tell.:detective:

    Pictures to follow when I meet up with Hawaii Ed.
    Last edited by a moderator: Sep 14, 2009

  2. 5-7HEAVEN

    5-7HEAVEN Guest

    The darn pocketbike engine won't start!:confused:

    Out of 100 pulls, the engine would fire up for a second, then quit. I believe the pullstart is taking a beating and might self-destruct soon.

    Maybe the pulse hole for the Walbro WT carb is blocked, or a diaphragm is leaking.

    Since this engine sat for a couple years, methinks it's the carb. Need to remove and disassemble it.

    I should also change the sparkplug.

    My last new engine that would not start at all was also for a pocketbike.
  3. Hawaii_Ed

    Hawaii_Ed Member

    Pocket bike engines are easy to use a drill on! :) I think it is a 10mm socket, just remove the starter assy and spin the fly wheel.

    If he ran it, prob has gummed fuel in the bowl/needle valve. I'd drop it and clean it all up and see what it does. Richard's pocket bike had sat for a long time and I had to do the same. Can also try just pulling the drain screw off the bowl and see what you get. No flow means stuck needle valve of course ;)
  4. 5-7HEAVEN

    5-7HEAVEN Guest

    Thanks for tips, Ed.

    This engine has two brass nipples on the bottom of the intake manifold. They're not being used, so I ran a short piece of clear tubing to both fittings to plug them.

    I can see a few cc's of fuel in the tubing, so it seems like fuel is getting into the cylinder. Still, the carb needs attention and I'll pull it today, after work.

    I'm pedalling a 24-speed bike five miles to work, until I fix "The Iron Dragon". It takes twice as long, but kind of peaceful. Time to reflect, very little stress or worry when riding the bikepath and sidewalks.

    Doctor says I need more exercise, so this helps.:idea:

    TREEWK Member

    Hi , I Tried Starting A Cag Motor With My Milwaukee Hd Drill Motor. It Tightened The Flywheel Bolt So Much, When I Tried To Remove The Bolt It Twisted Off. Most Flywheels Have Two Threaded Holes Near The Center Bolt. In The Future I Plan To Make A Plate That Will Use The Two Bolt Holes And Weld A Nut In The Center For Starting Or Checking For Spark. Ron
  6. 5-7HEAVEN

    5-7HEAVEN Guest

    LOL, I tried that "drill start" with a Milwaukee drill on my 460 engine. It didn't work for me.

    Ron brings up a point; with my luck, same thing would happen.

    TREEWK Member

    I Have A Confession That I Hate To Make. Last Year I Bought A "zipcycle", A Used 25cc Manufactured Mab, Friction Drive (now Out Of Business, But Web Site Still Up). I Ran The Motor With The Same Drill, Lol. I Think I Put Many Miles On The Motor With The Drill. It Would Pop Ocassionly. I Rebuilt Or Cleaned The Carb, Cleaned The Flywheel Magnets. Days Later I Realized, I Was Turning The Motor In The Wrong Direction. (please Do Not Tell Anybody This). Then When I Tried To Run It In The Proper Direction, The Flywheel Nut Screws Off. I Double Nutted It And Tried Various Tricks With Out Success. The Jerking From The Compression Stroke Loosens The Nuts. Then I Came Up With The Plate With Two Bolts. That Was Last Year. My Face Is Still Red !!! Lol. Will Get To It Some Day. The Zipcycle Is A Neat Bike. Ron PS The lg gas tank is plastic. The gas cap is a nut. It is a glove box of sorts. The gas tank is on the motor. If i get it running i could install a CG tank.

    Attached Files:

    Last edited: Sep 16, 2009
  8. 5-7HEAVEN

    5-7HEAVEN Guest

    I removed and disassembled the Walbro carb on my pb engine. It was very clean with no foreign material whatsoever inside. The carb's pulse hole is clear and ends where the reeds are. The carb feeds the crankcase directly, and not to the cylinder. Carb gasket is not blocking the pulse hole.

    Replacing the sparkplug tomorrow.

    Fuel/oil ratio is 16:1.
  9. Hawaii_Ed

    Hawaii_Ed Member

    hmm, no idea how the walboro style is setup! On our pocket bike, it has a drain hole on the bottom of the bowl, if you have that you can check fuel flow?
  10. 5-7HEAVEN

    5-7HEAVEN Guest

    No float bowl, Ed.

    Carb looks new, diaphragm still intact.

    When I removed the manifold and reed set, I could see the engine had a stuffed crank, which was encouraging.

    I'm searching for the model number so I can buy an exact duplicate. Cost is a reasonable $35 from DDM.

    I need to look for my spare pb engine, but that one didn't want to start either.
    Last edited by a moderator: Sep 18, 2009
  11. Hawaii_Ed

    Hawaii_Ed Member

    Well, I do have a complete, running pocket bike :D, can always "borrow" this weekend if you want!

    One of the electric start cat-eye engines would be cool, plus they have the charging setup!
  12. 5-7HEAVEN

    5-7HEAVEN Guest

    Electric start would be nice!
  13. Xqizid

    Xqizid New Member

    Does it run when you put fuel in manually?
    Checking the connection where the lead attatches to the coil might be a good idea. It isnt the best setup on these motors, just a screw.
  14. 5-7HEAVEN

    5-7HEAVEN Guest

    I'll have time to troubleshoot on Saturday.

    Things to do:

    Mix fuel/oil ratio to 25:1 or higher

    New sparkplug BPM7A gapped at .028"

    Check for spark and fuel.
  15. 5-7HEAVEN

    5-7HEAVEN Guest

    It's Alive!!!

    Hawaii Ed dropped by to check out "The Iron Maiden" and its HP pocketbike engine. His starting technique is different, being short and quick. After he adjusted the throttle for a smoother pull, the powerful engine roared to life.:tt1:

    Ed says it sounds MUCH more powerful than my 5hp GP460 engine which was originally on the bike.

    The engine couldn't idle and Ed noticed that the Walbro carb was mounted upside-down. That meant that my carb adjustments were incorrect. When we readjusted the carb, the engine settled down to a steady rumble.

    Fuel/oil mixture was a heavy 16:1 ratio. After a few minutes of running, the 25:1 gas in the reserve tank was allowed to flow into the goped tank. This will keep raising the oily mix until it stabilizes at 25:1. Later I'll experiment with a higher F/O ratio as the new engine breaks in.

    It's late afternoon and cooler now. Time to test and tune at the park!

    I'll then ride "The Iron Dragon" over the hills that proved to be too much for my 460 engine. :confused:
  16. Hawaii_Ed

    Hawaii_Ed Member

    Sometimes a new set of eyes can see things from a new perspective :)

    This bike is going to be insane! I have a stock pocket bike for my son, and this beast screams in comparison. If the tires stay in one piece, I bet it will best my top speed easily!

    Attached Files:

    Last edited: Sep 20, 2009
  17. 5-7HEAVEN

    5-7HEAVEN Guest

    Thanks for dropping by, Ed.

    I went for test and tune today. Even in poor tune, the pb engine climbed better than the previous GP460 engine.:detective:

    However, its carb is also sensitive to adjustments, and it's a BEAR! to start.

    The engine stalled a few times, and it wasn't easy starting. Two miles from home, the pb engine stalled and wouldn't start. Had to pedal home.

    I pulled the ADA aluminum head to check which compression dome rested above the piston. There was no stamping onto the compression dome, so I'll just order a 13:1 dome to be safe.
    Last edited by a moderator: Sep 20, 2009
  18. Hawaii_Ed

    Hawaii_Ed Member

    will prob start and run better with less oil :) 25:1 is the break in, then 50:1 after that.
  19. TREEWK

    TREEWK Member

    5-7 , I Have One Of Those Engines (52cc Big Bore Kit) Mine Has The Red Head, It Even Sounds Mean. Also Have Some Of The 49cc With Out The Big Bore Kit. When They Are In The Pocket Bikes They Have Air Shroud All The Way Around The Cylinder. After I Run Them Awhile, Seem To Have Trouble With Them. Am Wondering If The Fly Wheel Fan Cooling Only One Side Is Causing Cylinder Distortation. I Mounted A Gas Tank On It, Off A Stock 49cc And The Larger Head Melted A Hole In The Gas Tank. You Need To Check Your Head Bolts Also. Had It On A Friction Drive And Now It Is On Cvt Free Wheel Set Up. Soda Cans Would Even Work For Shroud Material. I See You Have The Aluminum Starter Cover. The Big Bore Kits Usually Have Them, More Compression Requires It, I Think. My Eng Would Like That Exhaust! Lol. . Ron

    Attached Files:

  20. 5-7HEAVEN

    5-7HEAVEN Guest

    Thanks for your input, Ron. Maybe I'll look into the cooling shrouds.

    Looks like you have quite the setups in your bikes.

    What's your top speed on each bike?