Best engine kit?

Discussion in 'Motorized Bicycle General Discussion' started by Kanye, May 2, 2015.

  1. Kanye

    Kanye New Member

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    crmachine offers a top end kit for the GT5 engine.

    http://shop.crmachine.com/product.sc?productId=97&categoryId=16
    http://shop.crmachine.com/product.sc?productId=57&categoryId=16

    But prices seem WAAAAAAAAAAAAAAAAAY over the the top.




    Then there's bicyclemotorworks

    https://www.bicyclemotorworks.com/store/products-page/race-ready-66cc-2-cycle-bicycle-engine/

    seems like good deal, has everything one would need.


    How much would building it home cost, tools included compared to the other two options?
    Are these kits really worth it, will they really perform better than the stock engine?
     
  2. Greg58

    Greg58 Well-Known Member

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    First welcome to the forum, your question has been asked many time here. All of the engine kits are made in China in several different factory's, some are of better quality. What some of the suppliers of the higher priced engines do is disassemble the engine and replace parts like bearings with upgraded versions, some even check the balance of the crankshaft to ensure you get a good running engine. As for building a bike at home that depends on a persons mechanical knowledge, you do have to fabricate some parts and pieces at times.
     
  3. Davezilla

    Davezilla New Member

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    Any engine purchased from Fred at crmachine.com is going to be a good engine since he goes thru each one, trues the cranks, uses the good bearings, etc... His performance engines are also really nice with a very noticeavble difference over stock.

    Bicycle Motor Works also sells performance engines and he goes thru them as well to correct the factory short comings but I'm not sure if he does anything with the bottom ends or not. He does sell some really cool looking engines tho, but I've never tried them or heard of anyone in here who bought one.

    If you want a really good stock engine kit for a decent price then Dax is the way to go with his balanced engines, these are very reliable and they run a LOT smoother than most others. Go to thatsdax.com and look around, his engines are some of the best.

    Another really good engine is sold by venicemotorbikes.com and his kits cost around $200 or so but his engines are also balanced and gone thru, he's another one I'd buy from.
     
  4. YesImLDS

    YesImLDS Member

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    See what I would like to see on the market is a basic engine that has all the free mods done to it to increase power while only increasing base price maybe thirty dollars or so. I've kicked it around about possibly doing something like this to sell here and there for some spare change and would be of good quality. All that you'd get ported and polish everything with a lighter piston providing better balance and a slightly milled head for a little more compression. All retaining the stock parts, but re-assembled with care unlike from the factory.

    Also like said above anything from CR machine will be good quality while some of his prices are definitely ridiculous.... I can't understand anyone paying a ludicrous amount for just a cylinder jug that's been ported out when the chrome lining on these can't seem to hold together for more than a month! (nevermind on that part because it doesn't seem that he sells just ported jugs anymore.)

    What I personally would do is just grab a thatsdax engine. He provides some cheap kits with upgraded bearings that are pretty nice for a decent price. Then learn to mod these out yourself and save yourself loads of cash.
     
    #4 YesImLDS, May 2, 2015
    Last edited: May 2, 2015
  5. Kanye

    Kanye New Member

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    Thanks for the replies, I think I'll go with the dax or the venicemotorbikes engine and mod from there.
    Since they're balanced.

    What tools would I need to do major mods the engine? Such porting the intake and exhaust, notching/ramping the piston etc.
    Some drills, dremel tool, and some clamps to hold anything down right?

    I wan't to be as budget friendly as possible.
     
  6. Greg58

    Greg58 Well-Known Member

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    One of the best ways to learn about engine mods is to use the search function, near the top of each page you'll see the "Google custom search" box, just type in "porting" and you'll find many threads from members over the years including how to do it.
     
  7. Kanye

    Kanye New Member

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    Did research on porting, it seems very daunting.

    Alright, I got one more trick up my sleeve, i'll report back it all works out.
     
  8. Davezilla

    Davezilla New Member

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    As far as porting goes, here are a few basic guidelines to get a very noticeable improvement without worrying about all the math and science in it all... it wont make you a 10hp screamer but it will give a nice torque increase with better power and rpm up top...

    Start with a new engine or cylinder
    go in and nremove all the overhanging nikasil from the intake, exhaust, and transfers
    take a sharpie marker and mark 1mm on both sides of the intake and exhaust port, and mark 1mm on the exhaust roof.
    now take your dremel and carefully cut to these marks using a carbide rotary file if you got one.. the high speed steel ones also work well on the aluminum but the nikasil can wear them out quickly...
    Once you got the ports opened up 1mm on each side of the intake and exhaust, and raised the exhaust roof by 1mm,use a sanding roll to smooth everything out but don't cut any more into the openings.
    next. Mark your piston crown where the transfers and exhaust openings are and ramp down about 1mm in these 3 places. At the bottom of the piston skirt on the intake side, cut 5mm off the bottom of the skirt and smooth it out.
    Clean everything up and reassemble everything.
    Now your engine will have better torque down low but capable of reving up at least 1000 more rpm on top.
    You can also boost your compression for even more torque by lapping off about 1mm or so by placing a sheet of sandpaper on a flat surface and rubbing the head over the sandpaper in a circular motion until about 1mm is shaved off...start with about 120grit paper and smooth out with 240 grit paper.
    You will have a noticeable increase in acceleration and speed just from this simple mod... to cut any further this is where you'll need to learn the math and science behind it all and use a degree wheel to ensure you don't go too far and mess up the jug and or the piston.
     
  9. Davezilla

    Davezilla New Member

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    Another trick is to remove the end cap off the muffler and drill 3 to 5 5/16" holes in the end cap which will add more top end power with slightly better bottom end torque and the bike will still be fairly quiet...
    there's a lot more power to be had with the exhaust by adding an expansion chamber pipe but a de restricted straight pipe will give a noticeable increase while keeping fairly quiet.
     
  10. Davezilla

    Davezilla New Member

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    Tuning the carb after break in also helps for even better power, but this is best done after break in because you need to run rich and oily until it breaks in or you can easily overheat and ruin all your work if you go too lean or lean it out too soon.
     
  11. Davezilla

    Davezilla New Member

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    Forgot to mention one of the easiest things to get a little more power and smoother running is while the jug is off to smooth out that casting ridge in the transfer port roofs... we don't want to raise this roof but removing the casting ridges in here does make a noticeable difference and should be done even if nothing else is done with the ports.
     
  12. Kanye

    Kanye New Member

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    Alright, thanks for the plethora of help.

    I already have a stock engine kit lying in my room, waiting for either a mountain bike or a cruiser with rim brakes. [​IMG]

    What I plan on doing is comparing the stock engine to the modified one.

    it will look something like this.


    Bone stock engine vs pro "full race" engine

    Home ported stock engine vs pro"full race" engine.

    The race engine of choice will be the best of both worlds from two companies. [​IMG]
    The full race engine, is going to be a crmachine bottom end with a bicyclemotorworks racing top end. [​IMG]

    At least that's a good in theory combo I know of.


    Has someone already run such as set up?
     
  13. Davezilla

    Davezilla New Member

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    I dunno what your budget looks like, but as far as full race engines, the only true full race engines are from Arrow Racing, and Fred makes one that's pretty strong as well but kept it piston port type. I really hadn't heard of anyone racing with a bicycle motor works engine and I really hadn't heard of anyone in here using one so I can't really say anything good or bad about his engines... I know they look really cool, but looks arent always everything...
    have you seen this guy's engines yet? http://arrowmotorizedcycles.com/index.html His full race version is a bit pricy but most likely the strongest of the ones available to buy. Fred's engines come in at a close second, he doesn't measure horsepower or boast numbers but his engine is really fast as well.
     
  14. Kanye

    Kanye New Member

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    Actually, I haven't, but it looks very promising honestly.
    My definition of full race was exaggerated, it's more like moderately modified.

    My budget is $730 and growing

    Which seems to be the better option?

    $500 for arrow engine.
    $140 for shift kit
    $50 for exhuast

    For a safer, beefy build, I'll add.
    $360 for Electra cruiser
    $120 for Double wall rims
    $70 Maxxis Hookworm.

    $690 sketchy build

    $1190 for safe build.

    I want to go with the arrow head, but it might be too slow.
    Or

    $500 for Dax 50cc KTMC
    $140 on shift kit
    $100 for exhuast.
    $150 mounting/misc parts ?

    $890

    I want to go with the KTM, but it seems like the expenses of building it will pile up.
    .
    I''m afraid of the clutch issues as well.

    Even with the unknowns, i'm slightly leaning towards the KTMC.
     
    #14 Kanye, May 4, 2015
    Last edited: May 5, 2015
  15. YesImLDS

    YesImLDS Member

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    Or $150 for basic decent kit
    $40 for dremel and bits
    $100 for mods
    = $190 for all the power you'd ever need.

    In all seriousness the most major mods I have is

    $45 fred head
    $50 snake pipe
    and a ton of custom porting and decking and polish, etc.
     
  16. Kanye

    Kanye New Member

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    I have a need for speed though, I wan't to cruise at 40mph - 45mph. Using it as a daily driver.

    That's why I've chosen such moderately modded engines, heavy duty rims, and a well built bicycle.

    I'm even thinking of doing a Honda GX160 build, but i'm afraid of legal issues and weight, so that's just a pipe dream.


    I also thought about doing a 110cc or 125cc 4 stroke pit bike engine, but I don't have to expertise to execute that.

    Looks like I'll just have to settle for the arrow two stroke.
     
  17. YesImLDS

    YesImLDS Member

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    My bike cruises at 45mph. Check out my build lots of go fast bits in it. You got to remember these things aren't super performance built and with more performance doesn't make them more reliable. My first build I got to go 45 with basically stock everything except an expansion chamber and some real nice porting and decking on the head. It's possible to do for cheap and a few hours of workbench time.
     
  18. Davezilla

    Davezilla New Member

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    Yup... I agree... it don't take much more than a dremel, a good set of carbide burrs, and a decent knowledge about porting and it don't take much else to make these capable of cruising in the 40 to 45mph range.. mine also cruises at 42 mph and that's with a 44 tooth rear sprocket and the stock nt carb... I do have a Fred head mane made my own pipe out of a ktm dirtbike pipe... each piece is matched to perform in the same rpm range, the porting, the exhaust, the gearing, and the jetting...
    The engine coasted me around $160 to build and I did mine with a bottom end from Dax, an ebay cylinder and piston that I ported and ramped myself. The pipe costed me a whopping $30, a few welding rods, and about an hour or so of my time, bringing the total cost of the engine up to around $190... Fred head included.

    There's really not a need to buy a prebuilt race engine when just a little porting and a little welding is all that's needed... you can buy a snake pipe or an sbp pipe if you cant weld or don't have access to a welder but that'll only add about 80 to 100 to the total price which still keeps your total price under $300
     
  19. YesImLDS

    YesImLDS Member

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    Nuff said Dave.
     
  20. Kanye

    Kanye New Member

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    As long as it can cruise i'm good. Wouldn't the KTMC from Dax be a more reliable engine?
    I'd also think you wouldn't even have to push it as hard either.


    Anyway, you're right about everything having to match up and be in sync for a specific power-band.

    I would do some porting, but I don't have a work bench, just a glass table, nor do I have any power tools.

    Nor do I have knowledge on two stroke porting, but since my brother is going to do this as well,.. I might as well save BOTH of us some money, by learning porting theory, proper tuning, and investing in tools.
     

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