4 stroke vs two stroke

Discussion in 'Motorized Bicycle General Discussion' started by jamesar, Jan 18, 2016.

  1. jamesar

    jamesar New Member

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    I've never used a 4 stroke engine on a bike but I just built my third two stroke model,it ran like it was broke in and balanced on the first run.the last one is still breaking in after a month .If anyone has built some 4 strokers as well as two how do they compare pros and cons.
     
  2. TheNecromancer13

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    Some people swear by the 2 strokes, but as for me, after my 2 stroke broke like clockwork every 2-3 weeks for a year, I switched to a 79cc predator 4 stroke, and haven't broken down once in the 4 months since (except for a broken frame and a flat tire, neither of which have anything to do with the engine itself). I have more power, higher speed, less noise, less air pollution, etc. The 4 stroke improved literally every aspect of the bike. I'd be happy to share my experience building 79cc predator bikes if you want to make one.
     
  3. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The 2-stroke engines are inexpensive, fast, tons of fun & there are tons of after market parts for them!
    There are plenty of experienced builders here (like me) who love them & ride them all the time with very few problems, but newbies usually have a lot of trouble with them.
    It really pays to NOT buy the cheapest kit you can find & do some research & spend the extra money buying from a respected vendor who will actually help you when you have problems with it.

    The 49cc 4-stroke engines tend to be extremely reliable but they're more expensive, slower & don't have any after market parts to make them faster.
    The most reported problems people have with them is the centrifugal clutch & the jack shaft systems... I've found the 7G belt drives to be more reliable than all the others if you know how to give them a little extra attention when assembling them. (These are what I recommend to anyone who's looking for cheap & reliable daily transportation)! ;)


    The HF 'Predator' 4-strokes are powerful, reliable, fast & fun with tons of after market parts available, but they're a lot more difficult & expensive to build properly!

    That's my 2-cents. :D
     
    #3 Venice Motor Bikes, Jan 18, 2016
    Last edited: Jan 18, 2016
  4. TheNecromancer13

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    That sums it up quite nicely.
     
  5. jamesar

    jamesar New Member

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    This is the kind of info I was looking for ,thanks. I would like to build a 4 stroker ,it will probably be slower but more dependable.One thing I'd like to know is what kind of actual gas mileage would you get from say the predator engine.I have two of the cheapest 2 stroke kits you can get from ebay,one is super smooth and can run wide open ,hardly any vibration,the other one slaps or vibrates near top speed but runs good anywhere below that.
     
  6. jamesar

    jamesar New Member

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    I was looking at the death row kit on gas bikes . net,do you have any experience with them.
     
  7. TheNecromancer13

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    Gasbike was where I got my 2 stroke that broke all the time. If you want to build a predator bike, I could provide you with lots of pictures of my building process and helpful links, but I suggest building one from scratch, as you'll know that the quality is good if you buy good parts. Also about 4 strokes being slower, that may be true for the 49cc kits, but my 79cc predator bike goes 45mph and still has enough torque to take all but the steepest hills. I have another 79cc bike that I just finished, it only goes 35mph, but has so much torque that it can pop wheelies if you're not careful.
     
  8. crassius

    crassius Well-Known Member

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    I get REALLY tired of mixing fuel for 2-strokes. That said, I'll probably never get a 4-stroke because they are too slow, and I refuse to ride a cent-clutch - just trying to blip the throttle a bit while working on one sometimes has me chasing it across the yard.
     
  9. jamesar

    jamesar New Member

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    Well I'm curious,what did you use for a jackshaft or transmission.
     
  10. jamesar

    jamesar New Member

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    I looked at a predator 79cc today,nifty little engine, With a 20%off coupon I can get it really cheap,I need to build a mount and come up with some kind of transmission.
     
  11. TheNecromancer13

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    Here's a picture of me with my most recent bike, zoom in on the mount and you might get some ideas, I can provide pictures of the whole process if you want, just pm me cause I don't want to upload 50 image links. As a transmission I used a jackshaft from GTC with a max torque centrifugal clutch.

    http://imgur.com/He6t3AV
     
  12. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Here's a tread on my old 99cc Predator Felt bike... The 99cc is the same size as the 79cc & will use the same mounts.

    I used a mount from a 49cc HS to make the new mount. (there's some detailed pics in the thread).

    http://motorbicycling.com/showthread.php?t=50513
     
  13. jamesar

    jamesar New Member

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    I now have a 79cc build,I've been riding it for over a week, It runs really good not sure how fast but a lot faster than my two strokers. I'm waiting on some high rise handlebars for it.The pedals are not nearly wide enough so for the time being I clamped on a rod for my feed and removed them.Pictures maybe later.
     
  14. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    I heat the 1-piece cranks with a torch & bend them out.
    This is a lot stronger than those wide 3-piece cranks that some companies sell). ;)
     
  15. curtisfox

    curtisfox Well-Known Member

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  16. jamesar

    jamesar New Member

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  17. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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  18. racie35

    racie35 Active Member

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    Dang Venice! Constructive criticism or just mocking someone's build?
     
  19. jamesar

    jamesar New Member

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    This is built from a 24 inch girls bike,I didn't like the low handlebars they tire my hands out so I went with the high rise.It seems to run quite a bit faster than my two china girls.I wished I had put it on a larger frame with fatter tires but it could be done easily.In three weeks of riding it has not given me any problems.The trans is a mini bike torque converter with the 10 tooth sprocket moved outside the box,works unbelievably well,has power and speed in one package.I have a speedometer coming.
     
  20. racie35

    racie35 Active Member

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    I'm sure you're happy James and that's what matters. When you say torque converter, is it one of those smaller cvt types? I wondered when those would start popping up on builds. Cool
     

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