38 thoughts on “Fred’s 2 stroke motorized bicycle engine rebuild #2 Putting it back together

  1. My bicycle might have that magnet problem you mentioned because when i built my bike it would hardly run at all ive fitted loads of mods just to make it even go 25 mph and you can forget about hills. Any advice where to get a 1 oclock magnet if that is the corse of my problem because ive completly run out of ideas now cheers

  2. Oh yes. A problem indeed! Well, try to get an old engine and take the magnet. Those old magnets are going to become valuable. There is a ton of these shit magnets around now. I would check your magnet. First, you can check to see if it is made with the thick plates (.030"). If it is, then you can take the next step to confirm. Take the 8mm nut off and check the position of the keyway. Then I would suggest to complain to the person you purchased the engine from. This will put the pressure on.

  3. thanks for the advice Frederic but unfortunately i don't have the option of having a spare motor or any spares come to think of it and in my county these motors are pretty much non existent and my funds can only stretch to buying the magnet itself at the moment just cant seem to find a website that sell the magnets thanks anyway fred keep up the good work and i enjoy your vids keep them coming buddy.

  4. being a small time mechanic myself, looks like that motor has or had lots of gunk that makes it look like you have lithium grease that's colored silver like your hands

  5. Hi Jose. Yes, you can get these "woodruff" keys from Treatland. If you don't know about Treatland, get ready to be impressed! Remember, some output sprocket keys are 2.5mm wide and some are 3.0mm wide.

  6. pk-80s are 3, grubes are 2.5. …when you thnk grube, always think "smaller". from the piston height to the drive sprocket and chain, to the transfer ports, intake ports, and lastly, woodruff keys. problem is- where to get em!? does Treats have em, really? that'd be cool

  7. Jake, where were you with this valuable info last week? I just ordered a grubee GT-5 skyhawk & I'm a firm believer in bigger is better It funny these two particular motors, as I was eyeballing a PK-80 on eBay but ended up buying the Skyhawk from "Gasbike website" @65% off the kit + free shipping. Now
    Im bummed out thanks Jake!! 🙂

  8. Hi Fred, nice video!

    May I ask about the piston positioning?  I do no think I have an arrow on my piston.  How do I know which way the piston goes on the connecting rod?  What are the bevels you speak of?


  9. question i have a 80cc skyhawk and it freezes when i let off the clutch what could be causing this it ran fine the first time i started it now you can petal it holding the clutch but when you let off it locks and will not start any help

  10. Well, it's clear you know what you're doing. Perhaps you or one of your subscribers can help me out with this problem. I recently put a 66cc kit on my bike. I was very careful with my build, during (and after) the run in period. I babied it, 16:1 ratio for twice the recommended mileage, 15 – 20 minute breaks after a 30 minute ride. The bike ran great for about a week, now it won't start. I get going about 8-10 mph, release the clutch, the motor turns for about a second… goes perrrrup then my rear wheel locks up. As I was able to repeat this process that would exclude a seized motor. I checked the clutch adjustment (on the motor, not the cable adjustment) it was a little tight, I backed off two "notches" on the butterfly screw? The wheel rolled when I pulled in clutch lever but not with it out, as it should. Tried to start my bike again and the same thing happened; perrrup skid! Seems like it's probably something obvious but obviously beyond my level of experience and knowledge. Can you tell me what is causing this and if so please and thank you, HOW to fix it? Thank you.

  11. I bought brand new and the shop won't put it together right keeps sliding down poll how to keep it from sliding DOWN ??,,?????? had it in shop 3 or 4 time he said he is not going to fix no more bought it brand new from his shop everytime I ride home engine slides down in back of ENGINE I wish iv could send a pick so SOME could show how to fix it the right way 600.00 bike no can't trust to RIDE because of ENGINE falling

  12. help any advice is better then the owener saying he not working on it any more Will I need help please explain why it keeps falling the engine he has u bolt under front part of ENGINE and a skinny thin piece of metal holding BACK of ENGINE

  13. well had this problem'quick fix'' put a price of innertube around post bolt back down an put a hose clamp tight right against the upper bottom of mount''' or take mount off' sand at a angle till it takes the gap out of post to mount,, either is safe an works'''nevr a problem again

  14. cool stuff bro. i'm still working on learning more about the bike i built. i customized the look, but the engine is-was a mystery! i broke my first motor! i even know the difference between a engine and motor now lmao! i was a designer now i'm a gear head! I love my tux rat bike chopper! Lucy is her name'o cheers! thanks for helping learn more!

  15. hey at 10:42 i didnt remove because i dont have the right tools but i broak it down as far as i can because it was really dirty and rusty but i put it back together and my bike wont turn over what did i do wrong

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