My Intro

Discussion in 'Introduce Yourself' started by Aqua, Jun 12, 2010.

  1. Aqua

    Aqua New Member

    Hi guys I just installed a 2 stroke china engine to my vintage 1993 proflex, what a pain in the rear! Anyways I am from BC Canada, and I am a gal who sadly knows little about engines but hey gotta learn somewhere.

  2. Happy Valley

    Happy Valley Active Member

    Hello and welcome to MBc.

    Hmmmm, '93 Proflex. What model is that? Dual suspension with the cross link front fork?

    Curious because I've only seen two Proflexes here, mine a '98 Animal and one that AlaskaVan has.
    Last edited: Jun 12, 2010
  3. give me vtec

    give me vtec Active Member

    welcome to the site... please ask any questions you might have.
  4. Aqua

    Aqua New Member

    This is one of the first ones, its the 753 model it only has the rock shox indy FS, but I found a source for elastomers for it and replaced the rear good as new.

    (not mine but exact same model)

    The question I have is my main issue, figuring out the chainline... because every time I sit on the bike the chain loosens just enough to jam.. driving me nutz!
  5. Happy Valley

    Happy Valley Active Member

  6. GearNut

    GearNut Active Member

    You will have to fabricate a spring loaded chain tensioner to push against the lower chain run. This will take up the varying chain slack created as the rear suspension cycles up and down.
  7. Lazieboy

    Lazieboy Member

    Yo what up.

    Hi. and welcome. This is where all your answers are. Pay em forward.
  8. Aqua

    Aqua New Member

    Yes, this is what I figured. Any links to examples of anyone doing this?

    @Happy Valley I have no idea why I said indy but I meant quadra shock on it, a little early for the indy models, lol

    Heres some pics (sorry for quality I was too tired to seek out my camera charger )

    It looks like it should work, right? but no, unfortunately because of the little but of slack in the chain, it jams and then puts so much force on my little chain tensioner creation it usually bends it into the spokes.


    The other issue is due to the small spacing of the rear suspension chainstays the pully has to be very low and close to the rear sprocket to give tension and not hit the upper chain.
    Last edited: Jun 13, 2010
  9. Neon

    Neon Member

    Aqua. I thought you did an excellent job of jamming the engine in the bike. Putting on the spring tensioned roller should solve the chain slack problems. Could try mounting the roller on the rear swingarm supports just above the top of the chain.
  10. Happy Valley

    Happy Valley Active Member

    Nice job of mounting!

    FS bikes can be problematic finding the right chain tensioner arrangement with the HT frame mounted engines. The configuration of that model PF swingarm exacerbates it somewhat though the good thing is the limited travel with the elastomer rear strut.

    Hopefully you can find a spring loaded arrangement that works.

    Here's just a sampling of DIY solutions:

    Thing is will there be room? Ya know, this is an ongoing issue for many so the archives here might yield an idea also with a search query like 'spring loaded chain tensioner'

    Another whole ball game would be a shift kit however can't say how it would work on your bike.

    Lots of creative folks here so there's bound to be a way to make it all work.
  11. Aqua

    Aqua New Member

    I am starting to question what I got myself into. Today I tried fabing a tensioner like this one someone suggested on another forum..

    except the arm is reversed and smaller of course.

    So my first go I used a piece of aluminum clamped with U bolts for the plate, and for the arm a piece of steel I attached the spring, got it lined up, seemed to work well.. but took it out and tried it, and I guess the idler was a bit off and it just jammed and bent the piece of steel!

    Now I am trying a super heavy duty piece of steel for the arm but having a lot of trouble aligning the idler (pulley) properly. FTR my chainline is straight as when i mounted the motor I measured, just getting this stupid idler in there properly is turning into a serious task!

    Thanks for the links I will go over them, heres hoping for an epiphany! :idea:
  12. Aqua

    Aqua New Member

    Had another try at it, perfect tensioner, perfect everything... however when I pop the clutch it still jammed and bent my bracket this time :/ I think it is time to say adieu and put the motor on my '84 apollo
  13. Happy Valley

    Happy Valley Active Member

    .......or try a rear rack mount maybe?
  14. Aqua

    Aqua New Member

    Yea, well, the motor was only 100 bux and when I have more time I will give it another go (I really want this bike for this week as I am going up in the woods).. I think maybe it was not the best project for a beginner, first I spent a day mounting the motor in the too small triangle, then 3 days figuring out why the motor was jamming as I had no idea what it was supposed to do... finally figured out the chain was just buckling a tiny bit and jamming (I think it was the angle of the motor) and the motor was fine.. then a couple days massacring various incarnations of chain pulleys :poop:.

    Maybe I will make a jackshaft type install on it down the road.

    But, good news, since I know how to do it now It took me less than 3 hours to put the motor on my apollo road bike (obviously the kit is made for this type of frame) and just had my inaugural ride!
  15. GearNut

    GearNut Active Member

    Congratulations on your ride!
    At least you got to enjoy it, instead of curse at it!