which should I get: 49cc slant or flat?

Discussion in 'Motorized Bicycle General Discussion' started by rudyauction509, Jan 27, 2013.

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which is better: 49cc flat or slant?

Poll closed Feb 1, 2013.
  1. 49cc flat head

    0 vote(s)
    0.0%
  2. 49cc slant head

    1 vote(s)
    100.0%
  1. rudyauction509

    rudyauction509 New Member

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    OK first of all I'm not getting a 66cc. I have 6000+ miles on my current 49cc motor and want to stick with that size. I ran a 66cc for 500 miles and the only good thing was the power. I couldn't stay on the bike for more than a few miles because of the vibrations, the bearings went, my kickstand fell off at 25mph, etc.
    I am going to start building a couple of bikes for a friend to ride and to sell. I have 2 options: 49cc slant head or flat head. price difference literally 1 cent. I want more power and know that the slant head gives that, but does it wear the bearings significantly faster, how much more power does it give, any other pros or cons that I should know about? vibration? excess heat? both motors are from BGF, I'm sticking with him, he's been great, even replaced my piston, cylinder and muffler for free when the muffler cap blew during break in and seized the motor. models are z50 and z50f. I have the flat head version now.
     
  2. jji7skyline

    jji7skyline New Member

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    I've done some research into the difference between the slant and straight head, but apparently the slant head does not provide a significance power increase over the flat head, simply because the slant head was not designed for power. It was developed so the kit would fit into smaller frame sizes.

    Therefore, I would recommend the slant head because even though your frame is large enough, the slant head looks cool, and leaves more space for spark plug upgrades, which tend to take up space if the spark plugs are longer.
     
  3. Greg58

    Greg58 Well-Known Member

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    I have one of each type, a grubee 48cc slant head and a bgf straight. They both run well, it took a little more to get the bgf to run as it should tho. The piston skirt did not clear the intake port like the grubee does, the power was less. After machining the piston for the port clearance the bgf runs as it should.
     
  4. rudyauction509

    rudyauction509 New Member

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    thanks guys, i thought it increased compression. I'm still leaning toward the slant for possibly building some smaller bikes. the 66cc slant I had threw me over the handlebars the first time I tried to start it, though, and had so much more power it's hard to believe it came just from an extra 17cc's.

    oh and what's with this message I just got when I tried to post this 5 minutes ago???

    "This forum requires that you wait 30 seconds between posts. Please try again in 43 seconds"

    directly copied...
     
  5. jji7skyline

    jji7skyline New Member

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    For increased compression, just get a performance head, but it seems you're not looking for power are you?
     

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