horse power mods?

[mean lean]

If you havnt seen ultimusmaximus's horse power updrades its worth a look. can anyone tell me if one of those pocket bike carbys would give some gains in performance on its own, or is the pipe and boring needed where its at? the stock carby on my chinese motor is a leaky little thing, not enough reason alone to justify upgrade though.

[andyinchville1]

A properly designed tuned pipe (expansion chamber) would provide the most power increase for the engine....The most economical way to achieve a higher top speed for the bike would be a smaller sprocket in most cases.
Hope this helps.
Andrew

[ultimusmaximus]

the key to increased power is letting the engine breathe better... a better carb that delivers air and fuel more efficient is going to compliment a tuned pipe with better exhaust flow...

[mean lean]

cheers fellas,
top speeds not my want, more pull and mid range is. need to source somone that can weld a pipe for me. andrew, ill be looking into a larger sprocket some time soon. can you tell me how to find thred on gear ratios, think im running a 44tooth about 40kmph comfortably. thanks again.

[andyinchville1]

HI Mean Lean,

I'm not too knowledgeable about metric and the KPH but generally speaking, every tooth you loose off a 44T sprocket on a 26" wheel will net you about a 1 MPH increase in speed and vice versa (1 tooth over 44 T you loose 1 MPH top end but gain more pull or torque) (this is with the dax 70 engine...different engines might behave differently because of the possibility of different primary reduction gear ratios and front sprocket sizes).

I'll be happy to help you with the sprockets....thanks for thinking of me!

Andrew

[andyinchville1]

Oh Mean Lean...I did post a pic of a closer to production ready tuned pipe on this site....look in the wild in the streets section.
Andrew

[mean lean]

hey andy,
thats a nice looking pipe, im worried id have trouble lining it up with my bike, steel frame mtb, motor sits a lot lower than with my aluminium frame. worth some thought. is there chance of forcefull manipulation? BRUTE mechanics?

[andyinchville1]

Hi Mean Lean,
Thanks for the comments on the pipe.The pipe has a header length and diameter that is very close to optimal for the system and it is adjustable because of threaded fittings so no manhandling needed to adjust pipe to fit most if not all bikes...Final install doesn't really require welding if the pipes are put together tight enough....I haven't welded on mine except in a couple places (fell bead weld) just for the heck of it and because it is goibg to stay on that bike....All metal is heavy enough that a muffler shop can MIG weld if needed....I had to make it that way because I wanted an adaptable pipe that would fit most if not all bikes and be locally weldable by a muffler shop because I figured most people won't have their own welder...To save me time (unless I can find a co to mass produce but then again there may not be enough demand to warrant mass production) I may offer pipe as a kit that would only require minimal welding.
Andrew

[nKKommando]

Expansion pipe from 80cc dirtbike and carb from 1980 yamaha GT-80 make this bike HAUL!! This thing will take off from right out of under me. After running a stock set up w/ ram air intake for awhile (the ram air is a great and easy modification that does add on top end as well as torque = HP) I decided to go all out and the gains are surprising. Its amazing it is the same chinese 80 engine. It is loud and has a mean growl from the exhaust. My advise: find some cheap parts and retrofit!

[JacksonCognac]

Originally Posted by nKKommando

Expansion pipe from 80cc dirtbike and carb from 1980 yamaha GT-80 make this bike HAUL!! This thing will take off from right out of under me. After running a stock set up w/ ram air intake for awhile (the ram air is a great and easy modification that does add on top end as well as torque = HP) I decided to go all out and the gains are surprising. Its amazing it is the same chinese 80 engine. It is loud and has a mean growl from the exhaust. My advise: find some cheap parts and retrofit!

word. IMO fancy velocity stacks and tuned pipes on $180 engines are not the answer to unlocking easy HP. Simple cheap and reliable gains on an equally simple and cheap motor are what I am after.