Happy Friction Time Twin engine build!

Discussion in 'General Questions' started by Gh0stRider, Apr 27, 2010.

  1. Gh0stRider

    Gh0stRider Banned

    Didn't know whether it fit in the frame mount or rack mount forums, so here it is in the General forum.

    Attached Files:

  2. RdKryton

    RdKryton Active Member

    It's different. I like it! I wonder how the throttles are synchronized?

  3. Wheres my dog

    Wheres my dog Banned

    Could easily set one engine up for low end power and the other engine can be set up for top end speed and lower rpm's....

  4. 5-7HEAVEN

    5-7HEAVEN Guest

    How About This?!

    Methinks power would get down to the ground more effectively if you put the friction drive up front.:idea:
  5. Esteban

    Esteban Active Member

    Redundacy ! Sometimes, you just gotta have it !
  6. nvrgoingslow

    nvrgoingslow New Member

    thats not going to work very well each engine has different specs, torque, hp, rpms and so on. its going to be really hard to mach each other, unless you put it up front but still looks like it wont work one engine will always be working harder than the other.
  7. 5-7HEAVEN

    5-7HEAVEN Guest

    You don't have to match front and rear engines' power, rpm,tq. Although I DID run identical Mitsubishi 43cc engines on "The Dragon Lady", I've used different rollers and drives. Once I ran Staton rear chain drive w/18.75:1 along with front 1.25" friction roller, then 1.375" roller.

    When you eased up on the front engine and floored the rear chain drive, it sounded like a transmission shift from 2nd to 3rd. How neat!

    As far as one engine working harder sometimes, that is true, and the lower operating engine LOVES the slower pace.

    I finally ended up using 1.5" rollers on front and rear friction drives, which worked best overall. No need to synchronize throttles...ever.

    My next project is a 1976 Huffy with 3-speed hub, front BikeBug .8hp engine and 2.8hp Tanaka 47R engine in rear. It'll be like an 80-lb boy pulling the front of the load...and a 280-lb NFL lineman pushing the rear. The boy will help out on low and midrange. Front engine would NEVER be able to match the rear engine's high rpm. The BikeBug's disengagement lever will disconnect front roller, and the rear engine will operate alone at high speed.
    Last edited by a moderator: Apr 28, 2010
  8. Gh0stRider

    Gh0stRider Banned

    Hey guys, I've got to 'fess up here.

    While that bike has two engines on it, only one is functional. The bike that they are mounted on is my "test mule", which happens to have a frame mount engine on it.

    While it wouldn't be too hard to have them running both in unison, that's really not my thing. It could be a nice experiment for someone though.

    In any case, I'll be posting some pics of the small installation issues I had to overcome installing that little minimoto engine.

    I put a total of 30 miles on it so far, and while it works ok, there are some things I need to address.

    One is that the clutch engages at too high of a RPM. It doesn't fully engage until you hit about 20 with the 1.25" roller. So minimum cruising speed is about 20, so you don't burn up the clutch. I guess that isn't so bad, as the minimum speed for a HT is only a little less with the engine lugging.

    The other is that the square can muffler is noisy, and I think it is holding back the engine at the top end. I can get about 30 mph on a flat surface, which is roughly 8,000 RPM. I was hoping for 10,000 RPM - but maybe the only way to achieve that is with a tuned pipe. I guess running it wide open during the first tank isn't really the greatest thing for a new engine, but a top end kit with piston, cylinder and rings is about $25.

    Another annoyance is that these engines have high compression, and are difficult to start. There is a de-compression groove cut above the exhaust port which helps a little.

    More to come!
  9. 5-7HEAVEN

    5-7HEAVEN Guest

    Nice con, Gh0stRider, lol! :jester:

    On a second glance, I don't see the throttle cable or fuel line on the pocketbike engine.:detective:

    You can easily move the clutch engagement to just above idle speed by changing to a clutch from davesmotors.com. :idea:


    You're right that the stock muffler limits rpm. I had thatsame problem on my Mitsubishi until I installed an ADA S1 expansion pipe. The sky was the limit with this pipe, even with my 12,000rpm+ GP460 engine.
    Last edited by a moderator: May 1, 2010
  10. Gh0stRider

    Gh0stRider Banned

    I was just waiting for someone to call me out for not having throttle or fuel connections. Heck, in that picture the rear brackets aren't even screwed into the frame!

    When I did get everything hooked up, I took the chain off of the HT engine and did my testing.

    I'll check out davesmotors.com for the clutch. It is a little annoying having the engine zing up to like ~5000 rpm and sit there until you hit about 20. Then of course it picks up nicely until it hits a wall at ~8000 RPM (30mph). A tuned pipe with a silencer might be the answer. I doubt I'd get to 12K like a GP460, but I don't think 10K is an unreasonable goal. I'm pretty sure these things hit around 10 grand when on a minimoto because of the tuned pipe on the mini.

    So much for not attracting attention!
  11. 5-7HEAVEN

    5-7HEAVEN Guest

    I bought a 3-spring pocketbike clutch for $9; it was worth 5 times that for my needs.

    This clutch is velvet-smooth and engages right off idle.:detective: