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  1. Mammoth

    My Weird obsession with stupid chinese four wheelers

    I share the same feeling with the early 1980's honda trx125. They are little pack mules and fun to ride with bigger tires. Im up to three of them. I learned a long ago that little is better for tight trails.
  2. Mammoth

    GX390 Build

    I have a coupler that will connect the 1" shaft to the transmission, and after that it will have a drive shaft to a propeller. Im going to try to increase the efficiency by not running a jet and go with a propeller built into a tunnel. The tunnel is going to be more of an arch. After...
  3. Mammoth

    GX390 Build

    To make a long story short bypassing all the failed ideas and get right to the point after weeks and dozens of attempts the engine finally fired up today. I had installed a new magnet to where I thought it would be, but it wouldn't fire. Had an electrical engineer show up today with all his...
  4. Mammoth

    GX390 Build

    This video has lots of good info about bore vs stroke.
  5. Mammoth

    GX390 Build

    Got the engine all back together and it turns over alot smoother now. Still doesn't fire correctly, but I may have found an answer. I'm thinking the magnet on the flywheel I'm using to trigger the pickup is too long. The instructions call for a 3/8" round magnet. I think the long bar magnet on...
  6. Mammoth

    GX390 Build

    While turning it over on the dyno it seems like its having ignition issues. Can't quite figure it out. The instructions say to set it at 18* before top, but it acts like its firing too early. I tried at 18, 9, 2, then went past top and tried 5, 10, 15, then 20. It fired a few times in a row at...
  7. Mammoth

    GX390 Build

    I see. The transformer still needs 100 amps to operate the welder at max 50 amps. I had to find a solution for the size of the cable going to the welder. A 100 amp 240 volt cable is prety big with screw in connections. By going through the transformer I can now plug it into a regular 50 amp...
  8. Mammoth

    GX390 Build

    I ended up ordering two individual bearings in ceramic for the side cover purchased through CBR Bearing. I will pm you about the snowmobile. Once I make real progress on that project I will start a thread on it.
  9. Mammoth

    GX390 Build

    When your racing every gain in percent counts. After a number of laps the first and second place finishers are usually right next to each other. That means the race was won by a fraction of a percent. Ive never had any negative side effects from thinning the dipper. You can picture how little...
  10. Mammoth

    GX390 Build

    It will go in an aluminum mini jet boat hull. Most people use a jet ski engine, but they use 2.5 gallons or more of gas an hour. Im going to build this boat for long rang. A stock 390 uses just under 1 gallon an hour. This is what I have in mind.
  11. Mammoth

    GX390 Build

    Spent the last three days getting the dyno ready and the engine mounted. Still have a few things to do before testing.
  12. Mammoth

    GX390 Build

    Learning as I go with lots of books for reference. Picking up tons of info on boat design. A lifetime could be spent studying propeller shape. It would be suicidal to the health of your fingers if you put them in the holes of the pull start handle. The plan is just to wrap my fingers around the...
  13. Mammoth

    GX390 Build

    Still going on this pushing it as much as i can, but progress is slow and hard won. Added a tach.
  14. Mammoth

    GX390 Build

    In 2013 I purchased all the parts to build a GX390, and they've been sitting in a box ever since. Im working on four other projects at the moment, but I really would like to get this together so I'm trying to fit it in. Here is most of the parts for this build. Got the rod, piston and...
  15. Mammoth

    They were just throwing these away at work

    This company is always throwing away something cool. Today it was four pumps and a generator. The pumps had two 8hp motors, a 5.5hp and a 3hp engine. The generator had a 3hp. Probably very low hours. I got one of the 8hp's and the guys on the crew got the rest. Have to keep an eye on the...
  16. Mammoth

    Cool short kart story's from your past

    I know most of us have cool short story's about karts from when we were younger that would probably be interesting to here. So please share If you got one. One I'm thinking of is when I was about 12 and we realized my friends landlord had an Invader chained to a pillar that was supporting the...
  17. Mammoth

    Building a Race Kart

    There's a couple motors out there that I don't see very often, but I always keep my eyes peeled in case one should happen by. I recently came across these 2 engines that I would have never guessed they'd cross my path here in the U.S. They are 2 stroke 685cc torque monsters built for sidecar...
  18. Mammoth

    New Motor on the Invader

    I like looking at all the pics on this forum so I figured I would add some from my collection. This 5 horse Tecumseh engine came with the Invader when I first bought it. I messed with it a little bit to get some more hp but it still wasn't enough. Purchased the 420cc and got to work. Noram...
  19. Mammoth

    Ever seen one of these?

    Just saw this and thought it was neat. Does anyone know the name of it? http://monterey.craigslist.org/snw/4879840464.html [/URL][/IMG]
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