New comer tips.

#1
just recently bought a mini bike with a 3 horse engine on it. with limited room with the frame to upgrade to a 5 horse (damn near impossible without modifying the frame) so im looking to get some easy tips on how to increase the output of my engine to go faster. new smaller sprocket, and removal of the gov are on mylist... anyone else got some tips to help me get some more speed outta this bike?
 

delray

Well-Known Member
#2
hey j3st3r ,welcome. are you using a clutch or torque converter? if you are using a clutch. a small sprocket will make the bike perform poor at low speeds and off idle take off. it will make the clutch work very hard and could damage it in the long run? if you only using it on flat ground you might be ok with a small sprocket? i had a 2.5hp motor with a small factory sprocket 65tt and change it to a 80tt. now the bike takes off faster,because the clutch ingages better and does not slip and also built a header pipe and exhaust systems to give it little more power. you can also take the gov-off and run your throttle right off the carb. also some the b&s carbs have a throttle stoper. check and see if that piece stops the throttle from fully opening,if so you can modifly it by grinding the throttle stop down little and allowing it to fully open and maybe polish the con-rod for strengh. it will rev-up higher rpm's and if it blows up? then you know you had to much power to it :thumbsup:
:scooter:...........................:thumbsup:
 
#3
yeah im using a B/S engine. ill check out the carbs in the morning. I'm using a 8 1/2 diameter sprocket and was told a smaller sprocket will equal more revs on the wheel giving me more mphs. At what point is a smaller sprocket too small and ruining the initial point to changing the sprocket?

(sry i dont know what 65tt and 80tt sprockets are, or a torque converter)
 

delray

Well-Known Member
#4
65tt and 80tt the tt means teeth on the sprocket. a torque converter is a belt system. the problem with a small hp motor you can sometimes run into a problem trying to push you and the bike off idle and low to med-range making it feel very slow. by me installing a larger sprocket on my small hp motor it gave it better low end power and good med-range. making feel like the bike has more power. the header pipe and exhaust help little too.:thumbsup:
i would try to keep the sprocket as big as possible. for example my bike had a 65tt(small,8inch or so dem#sprocket) on 14inch tall tire. now install a 80tt(9 3/4 dem#) giving me about 2inch of ground clearance. no problem with ground clearance when riding in the yard and stuff:thumbsup: if you install a 5hp motor? that would change everything,because of all the power it can give you.
:scooter:..................
 
#5
I had a BS 3hp on my small bike and the sprocket was 8 1/2 inches. With a 12" tire (6" rim) you don't want to go bigger because you bottom out in turns.

60 tooth is 7/3/8" and 72Tt is 8 3/4" so mesure your sprocket or see if it has a number on the face. If you go smaller than 70T you might have trouble getting of the line altogether with a tired 3HP. (depending on tire)

Alot of the 3HP engines came off of edgers so they can be a little gutless but mine will go pretty fast once up to speed.

Tuchumseh makes a 4HP engine that is small and has more poop, it also looks old school. GTO
 

delray

Well-Known Member
#6
yes, you what to give your self some ground clearance. one other option is using a jackshaft to gear it right,if you have the room to mount it or a bolt on jackshaft:thumbsup:
:scooter:.......................
 
#7
i was browsing the internet trying to find an example of what my frame might be, and i discovered that my frame is a 'Bird - Duck.' Its got a chopper feel to the frame and the back end of the frame is shorter then the front, leaving me NO room to go to a bigger engine. Unless i weld a new mounting plate and slide the engine position forward, but then i think the engine will get in the way of my leg clearance. I want to put a 5 or an 8 on it, but i don't think i'll be able to without moddifying the frame. I'll bring it up to my Small engine repair place down the street, i see them messing around on carts and minibikes all the time and see what they say.
 

jeep4me

Active Member
#8
It sounds like maybe the guy you bought it from didn't really know what he was doing when he set the bike up. maybe you should go back to him and ask him to make it go faster or at least pay for some of the initial cost. It's quite possible he has another bike that would better serve your needs.
 
#9
Hey J3st3r

You should be able to fit in a HS50 small block Tecumseh 5hp in it. Brandt at www.ruppparts.com is your guy! He knows how to push alot of power out of that little engines. He has had the fastest Flathead out at windber for years, and beating 8 and 10 hp engines.


Josh
 
Top