what mods work best?

Discussion in 'Performance Mods' started by flyingpez, Apr 24, 2010.

  1. flyingpez

    flyingpez Member

    I'm new here but I have worked on real motorcycles for some time now and I'm looking to make a high performance bike (at least something that will
    go 35-40+ mph) Ive been looking for a day or so and Ive found a number of mods and seem easy enough. here is what I know of so far.

    1.boost bottle.
    2.aftermarket carb. ("speed" or "CNS")
    3."tuned pipe."
    4.38ish tooth sprocket.
    5.bore out the exhaust port.
    6.reduce the head chamber size.
    7.and maybe even nos

    what do you all think? what mods am I missing?


  2. rockvoice

    rockvoice Member

    just a tuned pipe and honing your intake to match (as close as possble ) the intake port on the jug will wake it up.
  3. chefdouglas

    chefdouglas Member

    One of the cheapest easiest mods is a good quality sparkplug gapped to .28 .Made a difference on my bike for about $3.
  4. flyingpez

    flyingpez Member

    so do you think if i just go with a tuned pipe, hone the intake, and get a new spark plug I will be fine? will one of the "speed" carbs or a boost bottle make much of a difference?

  5. chefdouglas

    chefdouglas Member

    I can do 35 with baffles removed from stock muffler, mild honing, spark plug upgrade and plastic air filter removed just foam filter on and intake and exhaust gaskets cut to fit opening (mine came with a hole half as big as the pipe), I also leaned the carb one notch. I plan on getting a tuned expansion chamber at some point. I'm over 200 pounds. Keep in mind stopping is more important then going fast. Disc brakes are the way to go or at leased upgrade from stock brake pads. Over 35mp I'm not comfortable on a bicycle and take my motorcycle instead. A new carb is probably a good investment but I'm not sold on the boost bottle, the concept is good but I've read mixed reviews on there benefit.
  6. flyingpez

    flyingpez Member

    how many tooth sprocket are you running?
  7. chefdouglas

    chefdouglas Member

    44 stock
  8. andrew88rmz

    andrew88rmz Member

    Im new to motorized bikes but i have worked on motocross bikes and raced them my hole life, so i feel im some what qualified to reply on the subject. I removed the base gasket, cut open my exhaust and removed the catalytic converter guts weldet it back up, and installed a number six ngk plug, I also dropped the needle on my stock carb. It made quite a bit of difference on my bike and ive put about 10hours on it since. It took me from 26mph to 31mph. It feels like i should gear it up now.
  9. flyingpez

    flyingpez Member

    Any pix Andrew?
  10. andrew88rmz

    andrew88rmz Member

    I posted some pics in the introduce yourself section. It says "what up mb in florida" or something like that.
  11. 210061741

    210061741 Guest

    Ok i will tell you what i do.
    But it is alot.

    STAGE 1

    #1 first get a expansion chamber ...Like SBP is great.

    #2 a lesser toothed sprocket will get you going faster but may loose some bottom end.
    I run a 36T for a long time with no problems. Now i am runing a 30T but my engine is hevily modded.

    #3 Get a high compression head.
    I ran the MM billet head and replaced it with this.
    For $30.00 it's well worth the money.

    #4 Base and head gasket.
    replace the base gasket with some thinner rubber fiber type gasket material from autozone.
    If the base of the jug leaks the engine wont run for long.
    I know normally the head gasket is aluminum.
    I have had alot of trouble with it leaking.
    I use the same rubber fiber gasket for a head gasket.
    So far i havent had any issues.

    #5 porting.

    Raise the exhaust port about 1mm higher and cut 1mm off each side. 1.060" from top of cylinder to top of port.
    Lower the intake port up to 3 mm.
    Don't widen the intake port you want velocity.

    Re jet the carb and get the thing tuned in as perfectly as you can.


  12. flyingpez

    flyingpez Member

    Wow thanks Rich that helps alot! I bought one of the cheap chambers that someone here was raving about (for $20)

    I was looking towards getting a smaller sprocket too.

    As for the head, Would it just be better to buy the new one instead of using a mill to cut it down? and If I do use a mill to cut it down instead how much is should I cut it down?

    are cutting out your own gaskets? what is the stuff called?

    and as for the carb, did you just re-jet the stock carb? is that all the "speed" carb is (a re-jetted stock carb)?

  13. chefdouglas

    chefdouglas Member

    Did the head bolt right on or did you need to mod it? How do you think it compares to the "slant head" high compression one made for HT?
  14. 210061741

    210061741 Guest


    The head is a near direct fit.
    The stud holes are for 7mm studs so they need opened slightly if you have 8mm studs. Not sure if i would try it with the 50cc and 6mm studs. But the bolt pattern is dead on for the 8mm studs.

    I got rid of the aluminum gasket and used some rubber fiber gasket material from autozone. It's holding up good. I noticed even with a stock head the aluminum gaskets leak alot.

    It is far better than the stock slant head.
    Has a little over 5cc combustion chamber.
    The stock head is 8cc.

    It also has a very nice squish band and the profile matches the piston very well.
    It takes the NGK HS style plugs.

    It is about an inch or 2 taller than the stock head.
    So you need the room to fit it.

    Heres a comparison shot of MM billet head / Stock Head / and puch head.

    It make the engine sound much better.
    I would run a NGKB8HS sparkplug or a similar heat range.

    It's on my bike now and i love it.

    Hope to make a video this weekend.
  15. chefdouglas

    chefdouglas Member

    Thanks! Looks like better cooling fins as well. I run the same NGKB8HS on my slant head and really like it. It made a HUGE difference from the stock piece of s@#t plug.
  16. 210061741

    210061741 Guest

    Your welcome.
    I just orderd another one of those heads.
    Also they have nice headgaskets for a couple of bucks.

    I am going to pick up som NGKB9HS plugs later today.

    Going to try it out in the puch head.

    Can't hurt to run cooler if possible.

    Worse case the plug fouls out.

    Best case it don't and my engine runs cooler.
  17. flyingpez

    flyingpez Member

    I bought a b6hs and a b8hs plug today and I got the gasket material. now I just need to get an engine bike and head. If I was to use a mountain bike what would be better 24 or 26"?
  18. chefdouglas

    chefdouglas Member

    It depends on your hight but a 26" will probably fit better(for the engine). A larger wheel will have a greater top speed a smaller wheel will have better low end for the same RPM. Smaller wheel is more nimble but larger smoother ride. I think most people use 26 but both have advantages. I would go with what feels best and get a sprocket that fits the style of riding and terrain. Also consider the components that come stock on both. I'm a fan of disc brakes for the front. I also recommend a dual pull brake lever so left hand clutches the right brakes like a motorcycle.
  19. flyingpez

    flyingpez Member

    ok. Ill try to find a 26" bike with disk but if not Ill work on making the other kind better. I will also look for a dual pull lever.
  20. 210061741

    210061741 Guest

    SBP has the dual pull levers.
    I have one from pirate cycles.

    Definatly good to have.

    I learned that when i went to pull the clutch and grabbed my front brake instead.

    Put me to the ground pretty hard. Bent my crank arm and smashe my knee real good.


    Right on man.