Generic China Doll 80cc

[RLS]

I'm curious if anyone knows just how hard you can push the 80cc Generic Chinese 2 stroke bike motors ESPECIALLY, with "hop up parts"?
So far I have in the works; a velocity stack and HiPerf Pod filter for "NT Speed" carbs, and a RSE Reed Valve intake replacement.

I am a pretty knowledgeable shade tree mechanic and I am aware of the boost these should add, and that without doing something to bump compression it is a bit pointless....so the stock head has just been shaved as well.
I ask mostly because China Cheap, nuff said right?!?!
What concerns me is the cylinder is not sleeved.... so we are talking about an all aluminum bottom case, jug bore, piston, and head with pretty much the only steel being the gears, con rod, wrist pin, bearings, and misc bolts....I am also aware I should replace every screw, nut, and bolt on it and toss these cheap substandard "SS" ones right in the sCrap can.
I would like input on what to get, what to do, and NOT to do to max it out without having it explode between my knees.
Keeping in mind I come from a long line of knuckle busters who thrive to do what others say cannot.....however I lucked out with more brains to go with the ingenius nature.

 

[bike]

How many horsepower do ya figgure?

Old whizzers are cheap and sound cool- why not try one?

 

[RLS]

How many horsepower do ya figgure?

Old whizzers are cheap and sound cool- why not try one?

First, I don't consider almost $600 for a complete 164cc Model H Wizzer that doesn't fire CHEAP.
Also I have yet to come across a genuine Wizzer that was "cheap" or wasn't totally thrashed already.
I think I would trust a "Flying Horse" more than this thing I'm working with... but I don't like the prices on them.
I also know that in the end if I swap everything but the base case and drive gears it will be more reliable, more powerful, and less likely to detonate.

The stock specs are as follows....
Stock Hp: 6hp@ 6k rpm
Stock comp: 6:01
Stock AVG max top speed: 25Mph

(I had it up to 28mph and holding for about 2 miles on level paved terrain @wot after mild tuning while fullstock) 30lbs 1984 Schwinn Cruiser5 + 6'2" 175lbs ME!

Recommended fuel: 90 oct 0% ethenol
Mixing Ratio:16:1 for new sets, 20: 1 after running 300m
Chain: 415 × 110 L 1"pitch
Driving Ratio:18:01
Capacity of Tank: 0.52 Us Gal
Ignition CDI 6v /Z4C 14MM plug
Clutch: Friction/ Dry

In other News, I do 30/35 MPH quite regularly on my 29" 24 speed Hardtail daily bruiser (Mongoose Deception 29er) which is front forks short of having NONE of its original cheap factory equipment.

F/R Brakes: Avid BB5 calipers and 6 bolt 185mm Rotors

Front/Rear Derailures: Shimano Avio/ Shimano Acera 8/9 SiS

Shifters: Shimano SiS RapidFire w/integrated brake levers and multi downshift 3/3/2 at full strokes

Bottom Bracket Hardware: sealed maintenance Free square taper insert

Chain ring: TRACER 175 5bolt Racing 3 plate CUSTOM geared @ 28/38/55

Front Hub: Modus QR

Rear hub: axle free DMR Bikes Revolver 36H

Qr squewer/skewerless internal threaded Freehub w/sealed bearings

Rear Gear set: Custom 30-26-21-18-16-14-12-11

Seatpost: Aluminum Servicable Adjustable Preload/Spring recoil type

Tires: CST GT 29 × 2.10

Rims: 700 x 54C Deep Vee Hammered finnish Charcoal ceramic coated aluminum

 

[bairdco]

You'll get better answers at motorbicycling.com, but I'll tell you what I've done.

I've raced the china motors since 2010 on kart tracks, and built my first bike in 2008.

I had the first bike documented at over 50mph, while everyone else was trying to hit 40, and this was before you could buy bolt on performance parts.

My last china race bike had around 10hp. Was in the top 3 bikes on the track, and snapped a ring the day of the race, after running perfect all day before in practice.

I took the motor off at the track, threw it in the desert, and vowed to never build another china powered bike.

The problem, as you suspected, is the chinese cases and cylinders. Without a steel or nikasil lined cylinder, snapping a ring will destroy the whole motor. The chinese bearings don't hold up to that much HP, and to me, blowing up an engine at every other race was frustrating, and just plain sucked.

The motors seem to have gotten a little better, but I'm not going back. There's a lot of good quality hi po stuff on the market for them now, but at the races, you see 30 guys in the first heat, and half of that with bikes still running by the final.

There are many engine options out there if you've got the skills to make them fit on a bike (or if you build the bike specifically for the engine) that will give you more power and reliability.

With a china bike, I've seen people spend a thousand bucks or more on their race engine, and they still fail. So you go from this "hey, it's cheap and easy!" To "this really sucks and I'm gonna get a motorcycle..."

As far as Whizzers go, not many people hop them up to go fast, and they're heavy, cost a lot, and should be preserved, in my opinion, and not raced (the "real" ones, I mean.)

I've been racing a modified 1970's minarelli V1 moped engine for a year with no problems, and it'll blow away any china bike. I'm in a different race class than them, though, and race against guys with briggs and Stratton motors, honda kart motors, and 212cc predator motors.

Mine has about 7-8hp, and beats 4strokes with 2-3 times that hp.

Currently, I'm building a new bike around the minarelli, with a chromoly frame and other custom, handmade parts to go even faster.

Good luck, but be prepared for problems.