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Discussion Starter · #1 ·
looking to build a bigger mini for dirt flat track. what is the best bike to start with that has available parts to build the engine and would be good to flat track?

looking for some suggestions from those of you that have built bigger minis.

my experience is mainly in 110's.
 

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not too familiar with flat track, (although it sounds awesome!)

But there is quite a cult following with xr/crf 100's, and a pretty huge aftermarket.



There are a few race schools, dirt track or otherwise that use exclusively xr100's

See this:

0005_red



Then again, I'm biased.... I have an xr100 ;)
 

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On a dirt short track, Big wheels and motors with heavy cranks are smoother, better control and easy to win races. "XR100 ect" If you go with a lay down motor,Id at least use a big flyweel and a heavy crank slinger motor if you want to be smooth "Trust me you do". Even on a Indoor on concrete. What are the rules-class-wheel size? A xr 100 or crf 150 on 17" wheels will not win a drag race against a worked 160 pitster ect but will win hands down on a flattrack. What are the guys that win youre class run?
 

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Discussion Starter · #7 ·
class rules are simple. any bike under 200cc and no knobby tires.

there has been a rm 80 a ttr 125 a kawi 200 2 stroke, i think it was a kdx.



a crf 150 could be the ultimate bike but, im looking for something less expensive that i can build into a winner. building a nice xr 100 could cost more in the long run but, building a mini is half the fun.
 

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Im actually building a old sl70 flattrack racer rite now. 150 YX motor, 14 inch wheels. The 12s on the bike in my avatar dont hook real good on dirt,still fun though. Works crazy good on indoor concrete though.
 

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rickyrider25 said:
class rules are simple. any bike under 200cc and no knobby tires.

there has been a rm 80 a ttr 125 a kawi 200 2 stroke, i think it was a kdx.



a crf 150 could be the ultimate bike but, im looking for something less expensive that i can build into a winner. building a nice xr 100 could cost more in the long run but, building a mini is half the fun.


You may be surprised. Check out EBay Motors real quick. There are a ton of new, leftover 17/14 inch wheeled CRF150r's selling cheap.
 

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wish i could post a link to HACKMUNCH's klx125, 190cc, kx 85 suspension build :D

id go with a klx125 or crf100. ttr's are good bikes, but i think that the kawi's are built a little better and then of course the honda.. can't beat a lil honda 4stroke!
 

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507 brett said:
wish i could post a link to HACKMUNCH's klx125, 190cc, kx 85 suspension build :D

id go with a klx125 or crf100. ttr's are good bikes, but i think that the kawi's are built a little better and then of course the honda.. can't beat a lil honda 4stroke!
For flattrack racing? A motocross frame? Do you race?
 

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geezer said:
Im actually building a old sl70 flattrack racer rite now. 150 YX motor, 14 inch wheels. The 12s on the bike in my avatar dont hook real good on dirt,still fun though. Works crazy good on indoor concrete though.
That's a sweet little flattracker you built there. Nice job!Got any pic's of the sl70 your working on?
 

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Pitviking said:
That's a sweet little flattracker you built there. Nice job!Got any pic's of the sl70 your working on?
Not yet but i will as I get it going. Its going to have modern forks and alum swingarm. Thanks Theres more pics of the Z in my album if you look.
 

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the drz/klx 125 is a really good motor to play with of the shelf u can get 150(143), athena has a 152 kit coming out in late jan 11, 190(187), and 170 kits, u can use a dr200 motor in that chassis too. If u get creative the possibilites are endless. Personally we have built 143,147,150,170,190,198,211,225,230, and right now we got them up to 274cc. rm 85, kx85/100 fork bolt right on as do most shocks. hot cams, and web cams make cams, so far my personal favorite was my supermoto bike 198cc ported head 28mm pumper carb 6 speed tranny, inner rotor, made over 25hp
 

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it's all about your personal opinion.

The crf/ xr 100 is going to be the most expensive to build

Ttr is going to be next best thing. You will need to get stiff springs and or thicker front oil in the ttr because as it sits stock is way to soft.

If you get a ttr or klx/drz get the l

The disk front brake(if you can run them) and

the bigger wheels are easier to find some knock off tires

unless you were going to go with sun 17 in rims

The klx/drz is the best choice by far.

Me being a die hard Honda rider... Like the klx feel for dirt track. All I have done to it is some renthal bars, bbr cam, bbr pipe, bbr stiff springs, 15w fork oil,

Next I'll do 17in sun rims and maybe a 150 bbk. Other than that the bike is perfect!



Just have to remember " the sitffer the suspension the better... only if it's slow and not like a pogo stick"
 

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The comment above about flywheel weight and momentum are very true,many flattrack bikes are down on HP but have heavy flywheels /wheels(rear) to aid traction with a wide TQ curve...I am currently putting a xr100 to ride on the ice in the winter, and on my 1/4 mile short track in the summer, I am going to leave the motor near stock, maybee a pipe & some carb work, and 16/19 tires& wheels to start....a few other mods will be heaveier springs F&R, new HD spokes on the rear , as the stockers are a joke, & a lower frame tie, because the frame is a little to limber , and it feels like a shock problem , when it is the frame loading & unloading....as far as dumping a ton of money in the motor first , I don't think that is a good plan , until you get the chassis working good , & it is obvious that you are out motored...(learn to roll thru the corners with as little off throttle time as possible, with less HP you can stay on the gas longer going in and get back to it sooner coming out, and can actually make up time /beat people with more power, cause they can't use it in the corners)hope this helps...shawn
 
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