Deciding on a 2 stroke kit

Discussion in 'Motorized Bicycle General Discussion' started by Len455, Mar 11, 2012.

  1. takeitez

    takeitez New Member

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    Just to clear some things up with what dragray said earlier it is not true that any engine will hit 50 mph and that it will just take a long time to get there. Most of these china engines will not get to 50mph because wind resistance gets to be to large. getting to 40 is easy and 45 is doable but 50 is really hard. (this is all with rear sprockets that are much smaller then stock)
     
  2. Len455

    Len455 New Member

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    Well thanks for all of your help guys. I just ordered the pk-80 from pirate cycles. Cant wait.:-||
     
  3. mapbike

    mapbike Active Member

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    One thing I wanted to point out here is that there isn't such an animal as an 80cc in one of these china girl engines, they are either 66cc or 48cc.

    Many of the problems people have with these kits are self inflicted but there are lemons as well because any of these kits can be a crap shoot like has been said many times, I suggestpulling the head off, the intake off and removing the cylinder/jug before ever even running the engine, replace the upper bearing/wrist pin bearing with a quality one, make new better intake gasket or purchsase upgraded ones from a vendor, replace the mounting hardware with higher quality bolts or allen head cap screws, make sure gaskets match the ports, remove any burrs in the intake or exhaust ports with dremel, and use a good fuel resistant sealer like Seal All or Permatex High Tack Sealer on jug to case and intake gasket, these engine aren't hard to put on many bikes but time should be taken to make sure everything is right or you will have solid heck from the get go.

    Just make sure things are right and ask lots of questions on here if you're not sure.

    If you do choose to replace the upper cage bearing here is the part # KBK 10X14X13, you can get these from www.motionindustries.com or if you have a motion industries industrial supply local just go by and tell them what you need, they may have to get it out of a warehouse like mine did but I had them in just 4-5 days best I remember, these bearings are one of the weaker points in these little engines, I have one with about 1500 miles on it now with it's original bearing and I've had engines go 200 miles and that bearing let go and trash the entire upper end of the engine, NOT a must replace item but one that many of us on here would point someone to do since they are known to fail probably more than any other critical internal part.

    There are many things that can be done to these engines and components but what I have listed above is what I think is a good idea from the start based on my own experiences with the ones I have.

    best wishes.....(^)

    Peace, Map


     
  4. Len455

    Len455 New Member

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    Cool thx. I'll do all of the free things i can to the engine then in a couple of months replace all of the cruical components and maybe get a boost bottle.
     
  5. mapbike

    mapbike Active Member

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    Personally I'm not sold on the boost bottle stuff for these engines, all I know is that the fastest bikes I've seen with these engines don't use them so I think the money is better spent on upgrades like a Billet intake, a better air filter or best of all the upper bearing I mentioned before that can be had for less than $10 there is proven benefit with these mods.

    Cleaning up the ports and make sure all the gaskets are top notch, on a 2 smoker an air leak can cook an engine pretty quick, in the beginning these engines run so rich that a small leak may not affect them much but once the carb is rejetted to get them tuned up nice an air leak is a real bad thing.

    Keep in mind that air leaks can happen easy on these little engines if special attention isn't paid to making sure you have good quality gasket, the stock intake gasket especially is junk on all the engines I've seen, not saying it can't work but I never use them, I make my own from good material always.

    Best wishes on the up coming project. dnut

    Map


     
  6. takeitez

    takeitez New Member

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    Hey map so the billet intake is good stuff? What kind of difference does it make?
     
  7. mapbike

    mapbike Active Member

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    Five things I think it has done on my engines with four of them being absolute facts.

    1. They match the port to the intake real nice, this makes the air fuel mixture flow easier into engine.

    2. They give the air fuel mixture a straight shot into the intake port which increases ease of flow.

    3. They allow the carb. to sit lower which can solve clearance issues on some bikes allowing use of either the stock or custom air filter.

    4. They have less of a chance of causing you to have an air leak between carb. and intake because the billet intake are grooved out toward the end and have an O-ring seal.

    5. Last but not least, I think because of the benefits I listed above that my engines are more responsive.

    Now, this is NOT saying that the billet intake is a magic bullet, but coupled with a free flowing exhaust, and a well tuned carb. all of the thing I mentioned above can be realized IMO.

    As you can see Ilike them for multiple reasons which are all benefits IMHO.

    Peace, Map






     
  8. Len455

    Len455 New Member

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    Cool it looks like ill be going to napa or pepboys and getting what i can.
     
  9. dragray

    dragray New Member

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    ok, yeah 50 is pushing it, but i was using that as an example....not an actual speed.
     
  10. dragray

    dragray New Member

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    yeah sometimes it pays to go with a place that offers a warranty that they actually stand behind.
     
    #30 dragray, Mar 13, 2012
    Last edited: Mar 13, 2012
  11. allen_okc

    allen_okc New Member

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    mapbike is correct in stating that there is no real 80cc for bicycles, but the engine claimed to be a 80cc still has the power to get my cruiser up to 40mph on flat land... 20mph uphill...

    but it looks like the engine i bought is no longer available, or if it is, it has a different name...

    my bike has been on the road for three years with no rebuild needed - i did get the racing carburetor for it which was a mass improvement...

    everywhere i go the bike has got a lot of attention from people, either offering to buy or a lot of questions about it...

    the 49cc is gutless compared to the quote"66cc" stealth motor... but remember, to tag and license it as a moped, call it a 49cc...

    here is a link about the motor i bought from zoombicycles...

    http://www.techdigest.tv/2009/02/the_zoom_bicycl.html

    my bike has proven itself time and time again to me and im convinced that i made the right choice with it...
     
  12. allen_okc

    allen_okc New Member

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    the stealth 80cc engine - three years and running...

    [​IMG][/IMG]

    [​IMG][/IMG]
     
  13. Len455

    Len455 New Member

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    Thats a nice bike! Were did you get it?
     
  14. allen_okc

    allen_okc New Member

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    its actually a long story how i got this bike - i never heard of a stretched beach cruiser until i saw this one...

    its actually one of the original stretched cruisers when they first came out - it didnt have have any markings or badges on it... very old bike...

    but i won it through a dare - the guy who owned it said if i could ride it up this hill without stopping i could have it...

    so i rode the rusty old bike up this steep hill which is a half mile long without stopping - what he didnt realize that the pedals up front like it is gave me leverage to do so... single speed bike...

    so i restored it and gave more gears from a mountain bike i had and put a full dress of lighting on it (turn signals, brake lights, headlights, tail lights and dress lights, all 12 volt system) and macargi forks and wheels and fenders...

    and of course a stealth engine kit... been riding it ever since...

    macargi has a bike similar to it...

    ive been offered 12 hundred dollars for it - all i can say is "NOT FOR SALE"...
     

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