Pull Start Anyone with pull start installition experience ?

Discussion in 'Transmission / Drivetrain' started by Porkchop, Sep 16, 2009.

  1. Porkchop

    Porkchop Member

    I started installing a pull start and centrifugal clutch on my Grubee tonight. The thingy that ataches to the crank shaft will not go all the way down before it bottoms on the 4 screws that bolt down the magneto. It won't go down far enough to even get the retainer nut started on the shaft. I got the starter from zoombicycles. I reviewed their installation instructions before I bought it, so I knew there might be some issues. I have a plan that I think will work, but just curious if anyone has done this, had the same problem and how they resolved it. My idea is to replace the 4 screws, that use a flat blade screw driver, and replace them with hex heads with a thin head if I can find such, torque them down and take a Dremmel tool and grind off what I need to get that thing to fit flat. I think if I grind the screws that are in there now, it might take to much metal away so that I won't be able to get the them out later. With hex heads that shouldn't be an issue.
    Thanks for any thoughts or ideas !

    ..... PC .....
    Last edited: Sep 16, 2009

  2. POPS

    POPS Member

    Hey PC

    What I did was put a lock washer between the mag. and

    the thingie and it left just enough thred to get the nut on.

    Make shure to use lock tight...POPS
  3. Porkchop

    Porkchop Member

    The "THINGY" is called an adaptor so I found out. Anyeway, my adaptor is bottoming out on the 4 screws that hold on the magneto. It won't go down onto the shaft far enough to get the lock nut started on the threads. I bought hex head screws to replace them in hopes that I can grind down the heads enough to make clearance and still have something left in case I ever need to pull them out in the future, and we know I will. I haven't tinkered with it yet today. I also found out earlier today that I have clearance issues with the centrifugal clutch. The only thing I can do that I can see is get a much thicker gasket. I filed down the 3 pins, and still not getting clearance. On my particular motor I could have left the pins alone. The cover that came with the clutch kit is hitting what I'd refer to as the pressure plate of the clutch. Even after grinding the 3 pins flush with the pressure plate. These crappy time engines are not for the mechanically chalenged ! Nor those without a good selection of tools ! I sure hope this thing, if and when I get it completed, runs better and is more reliable than the ease of the assembly has been.
  4. POPS

    POPS Member

    I just remembered what I did. I bought a star lock washer and put it between the mag and the bell then used a reg. nut on the shaft with lock tight. When you snug it up it crushes the star lock washer to hold it in place but still gives enough clearance to clear the mag.

    As for the clearance problem on the other side I did not have an issue but I read that some people used 2 gaskets.

    IMHO it would be a lot easier to use the washer method than grinding...POPS
  5. Porkchop

    Porkchop Member

    Duh on me ! I got mine together tonight using hex heads as I mentioned. I didn't have to file away much. I wish I had thought about using star washers. Very good idea. I think I'll redo mine and install one of those. I started working on the centrifugal clutch. If you look at the insdtall. inst. on zoombicycles web site, I did exactly what it says, but the cover rests against the pressure plate. The only way I know to fix that is make a gasket somewhere 1/8" and 1/4" thick. I'll work on that tomorrow if I can. Thanks for the star idea !
  6. jimraysr

    jimraysr Member

    Pull Start Kit.

    Would it work to drill holes in the "thingee" / adapter so it will fit flush to the magnet rotor?

    I will soon know the situation as Zoom shipped one to me today. I have a 48cc that somebody gave me. Its ignition module has a 98 date in it. Maybe I need to put it in a museum for MB? Think of all the China parts we could gather for displays. From one build, I have two driven sprockets, one rag joint, one transmission, one teardrop gas tank, one one piece crank, sprocket and bottom bracket bearings and two clutches plus enough metric bolts to keep one neighborhood Home Depot in business.

  7. POPS

    POPS Member

    Your very welcome and thanks for the comp.

    Watch out on the bell pullstart. It has quite a bit of play on the shaft.
    If it is not in the right place the rope will hang up on the recoil.
    Litely snug the nut and then put the cover on and gently pull the rope .
    If it recoils good then pull the cover again and snug down that nut. Try to center it as best as you can.

    As far as the other side go's I had no problem with rubbing after grinding on the pressure plate.I guess some fit and some need an extra gasket??

    What I did was use some extra thick green marine greese on the pressure plate gear and I put quite a lot. I have not run the motor yet. If you look at the bottem of the PP. cover, there is a spot where you can tap in a greese zirt. I would do that as it looks as it would be right over the gear to give it a squirt now and then as it would be a big hassle to take it all apart just for greese!

    The reason I put a lot of greese on is I took apart the CF.clutch and reversed the spring in it so it freewheels both ways. This way it will not peddle start, only pull start, but you can then do away with the manual clutch lever, cable, arm , pin etc. and you can still peddle the bike without turning over the motor.

    If you never disengage the manual clutch from new..("Can't get clutch to disengage because it's locked tight") I believe it will last forever. Hope this all helps in your build!!

    PS. You might also consider drilling a hole where the star nut clutch adjuster is and put a rubber plug, (cap like) so you can get to it with out takeing it all apart....POPS
  8. POPS

    POPS Member

    Hey Jim

    It's just to easy to use a star lock washer in there as a spacer. I would go that way....POPS
  9. Porkchop

    Porkchop Member

    I like this idea the best so far. I probably would not do this myself. I'd have a machine shop do it. One of my best friends owns a machine shop. Problem is getting him to do stuff. This is my first frame mount build. I've read where these things vibrate like craqzy to start with. I don't have a clue if the preciness of the holes would affect the vibration or not. I would think yes at the RPM's these things turn. I'll probably leave it alone for now, build a bike and evaluate it. If I like it then I'll worry about fine tunning things. Only take about 5-10 minutes to completely disassemble on of these little engines. not much longer to bolt it back together.
  10. Porkchop

    Porkchop Member

    Pops, I talked to zoombicycles yesterday about my issues. Andrew told me I still need the manual clutch along with a pull start and a centrifugal clutch. I know about the one way bearings on the clutch. I've been experimenting with mine while it's under construction. I do not see in any way why I need a manual clutch. I don't care what so ever about being able to jump start the engine. I don't see how it can be jump started with a centrifugal clutch. Am I missing something here ?
    What spring are you referring to that you turned around ? I have taken every nut, bolt and screw out of this engine, except I completely left alone the whole clutch actuating assembly. However I did remover the pressure plate and clutch plate. So right now it's all still fresh in my mind. Might not be tomorrow though. Ha ! Ha !
    Seems like this stuff is hit and miss. People have different problems with different engines I guess. Sopunds like Q.C. and inconsistantcies to me.
    Thanks !

    ..... PC .....
  11. POPS

    POPS Member


    If you go to the (other channel) and look in

    2 stroke bicycle engines and kits I bumped a thread

    today that will tell you all you want to know about

    the CF clutch...POPS
  12. Porkchop

    Porkchop Member

    What's the "Other Channel"
    If it's something you can't post here, PM it to me !
    Thanks !
  13. POPS

    POPS Member


    I don't know why but I can't PM you???

    I did threw your visitor place on your site...POPS
  14. Porkchop

    Porkchop Member

    O.K. I read your posts on the other channel. I was going to PM this to you, but decided to post here for others like me that don't go to the other side. A few questions. This is my first time I've ever heard of or gotten any experience on this one way stuff. I realized last night that the one way roller on my friction drive build operates pretty much the same way as the one way system works in this centrifugal clutch. I think it's a clever idea. Anyway, I plan NOT to have a manual clutch on my bicycle. And again, this is my first frame mount. If I install my centrifugal clutch as it's supposed to be, meaning straight out of the box with no modifications, with no manual clutch, how should I expect my bike to start and go ? I have already installed a pull start. With no manual clutch, when I peddle my bike, is it always going to turn over the engine, provided the cent. clutch is installed with the pre-tensioner spring, or what ever you refer to it as, is installed correctly ? It's my understanding from you other post that it will. Correct me if I'm wrong, but your post on the other channel said you removed the spring in the clutch, rotated the bearing race anit-clockwise and put a couple of welds on it to get completely rid of the manual clutch and make your whole clutch assembly free wheel, meaning you have to get the RPM's up so only the clutch shoes do any pulling. Do you have to do this to get rid of the manual clutch completely so while under noraml peddling you won't be turning over the engine ? Can you not just remove the spring, remove the roller bearings, replace the race and weld it to the clutch drum ? After welding, what are the roller bearings good for ! Sounds like I'm wanting to do my bike like you did yours. I want no manual clutch at all, I want to be able to peddle my bike as normal, puill the cord to start the engine, give it throttle to make it go, just let off the htrottle and apply brakes to stop. Of course I realize as long as the back wheel is rotating, everything in the engine from the clutch drum back will still be in motion. Just like an automobile with a manual transmision with the clutch disengaged.
    THANKS !

    .............. PC ...........
    Last edited: Sep 18, 2009
  15. POPS

    POPS Member



    #1...Yes, When you peddle you will always be turning the motor.

    #2...Yes, But I did not tack weld it as I figured I could just reverse
    the spring (retaining clip) and put a 180 twist on the end of the clip
    that attaches to the bell and play to find the positon with the
    roller bearings ( keep moveing around the bearing race to find
    the sweet spot where it will line up with a hole in the bell to clip
    on and preload the center to the left. Anticlockwise) That way
    if you change your mind you change it back with little to no problemo.


    #4...No...Without the roller bearings the bearing race will flop around the
    shaft and not work!

    Hope this helps ya out PC...Any more Q's.. I'll be here...POPS
    Last edited: Sep 19, 2009
  16. Porkchop

    Porkchop Member

    Thanks Poos. Duh to #4. I don't know what I was thinking. Of course the bearings have to be there !!! What would happen it you just removed the retainer spring/tensioner ? Zoombibycles told me they actually didn't know if that clip had any real value. I'm wondering now if it's just there so you can peddle start. I also have doubts that it will last very long. I think Ill keep this one as it is and make another one that works from the other direction. I'm afraid of bending the hook on it to be able to flip it over. Don't want to weaken it. So...what do you know about removing it all together ? Looks like it's going to be a while before I get this engine mounted on a bike anyway. I've decided not to mount it the bike Ive been working with. It's a 1972 Schwinn Collegiate that's to good of a bike to mess up, like breaking spokes and trashing rear wheels. I also don't want to remove the chrome fenders. So....I've got to find another bike.
  17. POPS

    POPS Member


    If you take the spring off and leave it off the clutch will have

    a mind of it's own, meaning it will kick in and out when it wants to.

    It will freewheel one moment and then the next it will lock up so

    you can peddle start. If you go back to that other thread you will

    see that is just what was happening to Lordo because his spring came off.

    That spring thing is all most like a paper clip. I don't think you can break

    it with out working it back and forth ( 180-180,180-180) lots of times before

    it will fail...POPS

    PS...And stop calling me poos...LOL
    Last edited: Sep 19, 2009
  18. Porkchop

    Porkchop Member

    Pops, that's pretty much what I thought your reply was going to be. But listen, I was thinking about the clutch earlier and I'm not totaly convinced that by removing the needle bearings that it will mees up something. If you know for sure, let me know. My engoine is sitting on my work bench withoput the clutch. I'm going downstairs shortly and fool with it and see what I can figure. I'm not afraid to tinker. The worst I can do is fix something where it can't be fixed, if you know what I mean. Ha ! Ha !
    I understand how peddling the bike will transfer energy to the motor and turn over the crank shaft. Thats in the one way bearing. I'm thinking howeveer, with the bearings removed that won't happen, but when the engine is running and RPM"s are high enough to make the shoes grab the drum, then that wii transfer power to the rear wheel. If the needle bearings are in position so that they are not grabbing, aren't they more of less acting as just a bushing ? Are they not there just to connect the crank shaft of the engine to the clutch anyway ? Again, this is my first and only encounter with one way bearings like this, and after working for the worlds largest engineering company fo 30 years, you can guess how my mind opperates. Sometime I have to tae things apart to see what makes them work and sometimes I just have to learn the hard way.
    Thanks for all your replies and help too ! Keep 'em up !
  19. POPS

    POPS Member


    #1...If you take out the needle bearings 2 things or three will happen for shure. The bearings are hardened steel, The race is not..not good on a hardened shaft.

    The clutch assembly will go down way further on the shaft and the gears will not mesh properly and it will wobble all over the place.

    Seeing that you are downstairs you will have likely figured all this out.

    #2...Yes but also as a spacer and hardened bearings for the shaft.

    #3..Yes but also for all the above reasons.

    I've allways had to know how something works. I take everything apart and put it back together. It's something I have to do. Hooked..gotta know!!!

    Your very welcome for the help and stuff. I think thats why most of us are here...To learn, help and share...POPS
    Last edited: Sep 20, 2009
  20. Porkchop

    Porkchop Member

    Pops, I just got through tinkering. I like the way you break things down in your descriptions Makes this simple.

    There is a sleeve/bushing that goes over the crank shaft. The needle bearings ride on that sleeve. Not the crank shaft it's self. The only time those bearings should be turning is when the clutch drum is not. That being said, because the bearings actualy move inward and outward from the center of the crank shaft, they should have nothing to do with alignment of the race to the crank shaft. When the drum turns, it puts the bearings in a friction/wedge bind. I guess you know what I'm talking about. The sleeve that goes down and around the crank shaft will go down only so far. Mine appears to be all the way down. The sleeve also has 2 flat side on the top of it. I don't know the technical terms for that other than maybe a shoulder. When I install the clutch drum and clutch it's self, it all fits flush with the top of the shaft. Also, with or with out the bearings, something is alredy out of alignment because I already have weeble wobble in the clutch drum.
    The gears appear to mesh properly. I don't recall if I mentioned or not that I spoke with zoombicycles and they told me they really didn't know what good that retainer clip was good for. I know I've talk to some vendors that sell parts but don't have the first clue about technical issues with them. Not saying zoom dosen't. But I know some are like that. Not trying to be contradictory, but do you know what you've told me from experience ? Bottom line, how do I get completley rid of the manual clutch an be able to peddle my bike or push it without turning over the engine ? Reverse the retainer clip direction ?
    Thanks !
    Last edited: Sep 20, 2009