Is putting a motor on a RACING BIKE with THIN TIRES dangerous?

Discussion in 'Motorized Bicycle General Discussion' started by fogell420, Dec 17, 2012.

  1. fogell420

    fogell420 New Member

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    My cruiser bike with a 2 stroke motor on it doesn't go that fast, maybe 25 mph on a flat surface. but i live where there are lots and lots of hills, and this bike can't get up lots of them.

    i want to put the motor on my racing bike because it's super light, but it has very thin racing bike tires.

    it also rains a lot in oregon and the ground is almost always wet

    is this dangerous?
    i want some detailed thoughts so i can make an informed decision about what I wanna do.
     
  2. Predator303

    Predator303 New Member

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    get a bigger sprocket for hill climbing and live longer. oh and if you know how, sand down the head of the engine for higher compression. that will give you a huge power increase. but shouldnt be done with an older engine since all parts are already used to the power of the engine.
     
  3. LR Jerry

    LR Jerry Active Member

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    If you only planned to race on a smooth track your idea might work. Otherwise its not a very good plan. I'm currently doing upgrades to my bike and will be back on the road soon. With the upgrades my ride will be a fully automatic 8 speed bike. Will be posting more pictures soon.
     
  4. fogell420

    fogell420 New Member

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    how do i sand down the head of the engine?
     
  5. Predator303

    Predator303 New Member

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    I sent u a message
     
  6. moonerdizzle

    moonerdizzle New Member

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    I rode a road bike for a full year, snow and summer. its not that bad, i had 27 inch tire up front and a 700C rim and tire in back. you have to watch the road, your tires will get caught up in cracks and stuff, but over all they work fine, and they work real well in winter time, cut right threw the snow and slush
     
  7. Nashville Kat

    Nashville Kat Active Member

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    You could try a 27" or 700 wheel on the front with some investment and see how you like that first- that's how I approached it

    And I liked it so well, I built another with 700c wheels and went back and put a 27 on the back of the other-

    Most bikes have a drilling for the front barke- you will need an older medium reach brake- if you have cantilevers that connect to the fork, they will not fit then- save them

    measure the reach and be sure to get the right one. Wheels can be had used sometimes on craigslist, but not always when you want them. I've got some that way.

    a 27 x 1 /14 is a great size- that translates to about a 32 mm 700c width, but tire manufacturers vary a bit there

    Don't recommend necessarily if you plan to ride a lot in the rain- I NEVER do unless caught

    but you'll find even with just the front the bike rolls and pedals a lot easier

    Other performance enhancers for the older bike might be a bilet intak ($20) and a 415 trike chain which is a lighter 415 chain with smaller plates and much less rolling resistence for the motor too. ($15 shipped) These two things alone might be the difference you seek. I get 30 cruise easily on the 66 with 27 x 1 1/4 and a 34 gear, and 35 plus opening it up- never do.

    If the hills are not miles long, a quicker lead in would give you more meomentum too.
     
  8. The_Aleman

    The_Aleman New Member

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    You might want to consider running a crosstrainer 700c tire on the rear, it would be more durable for starts and stops than a road racing tire.

    Although that said there's plenty of durable road tires, example: These multi-colorable tires made for skidding :D
     
  9. thegnu

    thegnu New Member

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    heres my thin tires an I routinely reach about 35 mph with this bike .its sitting on 1 an 3/4 tires
    Gary
     

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  10. Nashville Kat

    Nashville Kat Active Member

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    Yes, you can also go to 26 x 1.50 and even 26 X 1.25-

    personally I'd go probably 1.50 which I believe are both more available and wear a bit longer- the high sidewall of the 26 alloy rim could probably use the extra verticle tire profile for ruts too

    So there are more options- I first went from 2.25 original beach tires down to 1.75, which is the size I rode a lot as a kid in the early '60's. The diference in roll and tire weight was astounding, so then I soon decided to put a 27 on the front-

    incidently, a 700 C wheel does work better in a cruiser frame than a 700C in terms of clearance- but the front and back brakes have to be different sizes of reach then.:
     
  11. Nashville Kat

    Nashville Kat Active Member

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    Here are some great brakes that will fit a lot of cruisers with 26 wheels on both ends:
    http://www.ebay.com/itm/BICYCLE-BIK...Cycling_Parts_Accessories&hash=item4ceeae72fa

    I got a pair awhile back- they look even better than in the ad- the anno aluminum is brilliant red- looks like a christmas ornament, and lost in the picture

    the back will generally fit a 700 or 27 wheel in the back too- but the reach is too long then on the front brake- a shorter one is needed then.

    the hardware for the brakes- pads and center pivot and bolts are usually a lot of this total cost if bought seperately. If you search a similar design for roadbikes- the price is much much higher.

    Happy Holidays

    .santa.santa.santa.santa
     
    #11 Nashville Kat, Dec 22, 2012
    Last edited: Dec 22, 2012
  12. LeTweek

    LeTweek New Member

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    I would never consider anything smaller than a 1.95 profile tire; at least where I ride. Glass, potholes etc. Cold [email protected]#$ snow?? leave it for the Knievels.

    "I know she's just a mailorder Chinagirl, but she means a lot to me."
     
  13. KCvale

    KCvale Active Member

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    If your bike is solid and you have good brakes the width of your tires is about comfort.

    What I simply can't go by without comment is this.
    That has to be most dangerous and ummmm.. 'not best' advice I have ever seen here and I have seen a lot.

    Unless you have a machine shop with a milling machine don't be trying to sand, grind, or otherwise screw with the most important part of motors combustion chamber is my advice.

    Want more compression and a REAL power increase for $8? Just drop in an NGK Iridium spark plug.
     
  14. locell

    locell New Member

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    LOL like putting a motor on a bicycle is safe to begin with!
     
  15. sputterputtBAM

    sputterputtBAM New Member

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    Right on locell, we can try to maintain some degree of safety though. this was not on my priority list though.
    I would, ALWAYS wear a helmet, ditch chain tensioner and shim motor mount to adjust chain, pants and gloves are good measures to minimize damages

    It's not such a big deal to sand down head for compression increase. I would research it here fist though. if too much is taken off it'll kill a motor quick/instantly.

    if you got $$ a better option is the aftermarket manic mechanic billet head. He built it with features youll never achieve with stock.

    On a budget? The best performance is gained through an expansion chamber exhaust.

    Put em both on and maybe a intake match the ports n gaskets up, theres not much more to be gained from a mb motor.

    Read the forum a lot... try to recognize hacks/half wits from gear heads.

    Good luck, I bought a KLR650
     
  16. KCvale

    KCvale Active Member

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    1. Safety really is #1, take it from a guy that has hit a van broadside and even with good insurance will be paying off medical bills for years to come and will the aches and pains the rest of my life.

    2. Please understand the precision involved in the seal between the head and cylinder, if it is not perfect you will loose compression, lots of it with an uneven surface on either side or even mismatched torque on the head bolts.

    The manic head for ~$100 gives a bit more compression but it's heat dissipation is the real bonus as I found out with that Silver Shifter eXtreme build last year.
    The thing is just a tad longer better plug accomplishes the same thing for $8 if heat is not an issue.

    3. 2 thumbs up on a good X-chamber exhaust, it's like a reverse turbo charger if tuned right and will give ya a real wallop HP increase.
     
  17. Easy Rider

    Easy Rider Santa Cruz Scooter Works

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    What kind of racing bike are we talking about? I say with a ht motor, it should be okay. If you plan on racing it on the track, I wouldn't suggest it especially with all the turns. A thin tire is bound to pop from a tire pinch.
     
  18. the chief

    the chief New Member

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    its fine, i have built a couple with 28c tires, you just have to pay a bit more attention to the road surface, watch out for pot holes etc. since you don't have as much sidewall to cushion the bumps, i would definitely recommend a suspension front end though, haven't done it with a rigid fork.
     

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