Pull Start Design Flaw and Fix

Discussion in '2-Stroke Engines' started by Hello Moto!, Jun 4, 2016.

  1. Hello Moto!

    Hello Moto! Active Member

    If you look at the first picture you can see that there was some major rubbing going on. At first I thought it was the outer cups of the insert that goes over the magnet. I was wrong. What rubs on these things is the two big bolt heads on that piece which you can see in the second picture. I ran this thing over 100 miles before I realized that it was the bolt heads and that it could be fixed.

    You can see in this picture the bolt heads that I'm talking about and also that they are the parts rubbing.

    IMAG1358.jpg IMAG1359.jpg
    In this picture I show my solution. It's a quite simple one and works perfectly. All I did was grind down the majority of the bolt heads with a sanding disc. I would say a good 3/32 of material was removed. Though there is still juuuuust enough to get a wrench on there but that will never be necessary.

    IMAG1361.jpg IMAG1362.jpg
    This final picture shows that my solution is in fact a solution lol. I colored the tops of the shortened bolt heads with a black sharpy to check for any friction or rubbing against the surface. This picture was taken after the engine was running for a good amount of time. Plenty of time to show if there is any rubbing and there is no black removed.


    So if anyone ever installs a pull start it would be wise to do what I've done before ever even installing it. It took me over 100 miles of riding and a lot of metal shaving dust in my magneto housing before I came up with this solution. Just thought I'd pass this on to any pull start users like myself. I can't live without these things lol.
    FurryOnTheInside likes this.

  2. Hello Moto!

    Hello Moto! Active Member

    By the way the 100 miles of riding was done on my old bike. I removed the pull start from that and I am using it on my new skyhawk build until a new one comes in the mail for this one. I wanted to get this thing started without the drive chains set up so I borrowed it from my other bike lol.
  3. ezrider

    ezrider Member

    This is a good newbie reference thread that I'll definitely bookmark. I know fer sure that the pedal crank won't clear the pull start adapter on my own bike, but I have no problems with that, so long of course as the engine STARTS. This is my last resort option...after I get through all the other start engine troubleshooting steps.
  4. Hello Moto!

    Hello Moto! Active Member

    I don't think the pedals will ever clear a pull start housing on any stock bike. I have 130mm bottom bracket with angled pedal arms give about an extra inch with the bend. After installation I have about 3/8" clearance from the pull start. I will give you a link to a better set of bent pedal arms. These ones are sold by boygoesfast on eBay. These are way better than the black ones that say gasbike sells. The boygoesfast ones are a 170mm pedal arm length and are chrome. Also, you can buy just the crank set by itself if you don't need the whole bottom bracket kit. I used an american to euro bottom bracket adapter and utilized a 130mm sealed bottom bracket. The black cranksets that you see have a very short pedal arm length and a much bigger bend in the arms. I have one on my other bike and it is terrible. The pedal arms are so short it's hard to pedal. IF you have to get a bent pedal arm crankset..get this one!

  5. Frankenstein

    Frankenstein Active Member

    The only pull start I used stopped winding itself back, rubbed a lot, then the nut that keeps the spring arm thing on the magnet came loose, got caught up in the internals, got shot through the pull start assembly (litteraly looked like a bullet hole, litteraly) and bent the crankshaft arm that holds the magnet, had to walk home with my bike, then inspection revealed the arm was snapped.

    After replacing the crank I found it was the wrong kind, needed a new piston, and long story short my bike never ran good after that day, it's currently a yard decoration at my friends house..

    I've never used a pull start since then.