Just installed doesn't really work




I just installed my Chinese 48cc motor. The motor starts + runs when I pedal, but is severely underpowered. I get no real pickup.

Now, when I disengage the clutch, if the choke is open (down), the motor dies immediately. If the choke is closed (up), the engine idles just fine (after messing around with the idle screw.)

Just to be clear. Here are some scenarios:
1) Compression start engine, choke is closed (up)
2) disengage clutch, motor runs fine.
3) Open up the choke, engine revs up, down, and then dies, all in 3 to 4 seconds.

2) Disengage clutch, motor runs fine.
3) Open up the throttle, engine dies in 3 to 4 seconds.


Any ideas?

ps - is there a good throttle twist grip on the market somewhere?
Motorized Bicycle Starting and Operating instructions: Friction clutch model:
1. IMPORTANT: PLEASE READ: Gas and Oil Mixture for Fuel ratio
The engine is a 2 cycle design, therefore, a gasoline/oil mixture is necessary. During the break-in period (1st 4 tanks of fuel, the ratio is 18 to 20 parts gasoline to 1 part 2 cycle oil. After the break-in period, the ratio is increased to 20 to 25 parts gasoline to 1 part oil. The engine crankshaft bearings are lubricated from the oil in the gas mix. A rich break in oil mixture ensures bearings will not cease during engine break in period.
!WARNING! Remember safety first: Wipe up any spilled fuel. NEVER fuel a hot engine or smoke while fueling. This could result in sudden fire, personal injury. Always move your motorized bike at least 10 feet from any fueling area before attempting to start it. Never leave the tank fuel cap off after fueling as rain water will contaminate the fuel and cause engine failure.

2. Open the fuel valve. Small lever pointed down with fuel line is in the open position.
3. Depress the small round cap plunger, ( Tickle button ), to prime carburetor. Located on left side of the carburetor next to the idle adjust screw. One or two times is enough.
4. Lift choke lever to the upward position. This is the small lever on the right side of the carburetor. All the way Up the choke is on. All the way Down the choke is off. Move progressively downward to off position during engine warm up period.

Starting procedure for Lever Friction Clutch Models:
6. Pull the handlebar clutch lever inward, to disengage the engine from the rear wheel.
7. Pedal; (down hill if possible for first start) A mid frame bike wheel stand is helpful to start the engine in place.
8. Let out the clutch lever all the way out and continuing to pedal. The result is a direct engine hook up with the rear wheel via chain and sprocket and the engine will now start spinning, Pedal until motor starts. Accelerate slowly at first.
9. Twist throttle to increase speed, reverse twist throttle to decrease speed. To stop, disengage clutch and apply brakes. To accelerate, pedal and release clutch while opening throttle.
10. Adjust choke to the smoothest engine running position.
11. After warm up push choke lever all the way down. If engine races too fast, or too slow, pull clutch lever and lock in the notched catch, stop and adjust engine rpm.
12. If the rpm needs adjusting, turn the idle adjust screw (left side of carburetor) in or out slowly to obtain the proper idle speed of about 1400 rpm +/- 100 rpm To correctly break the engine in, Do not exceed 15 mph or 30 min. continual running for the first 50 miles during engine brake in. Engine will develop more power after break in.
13. To stop the engine, push Kill switch and turn off gas valve at tank. Turning off the gas will prevent fuel from being siphoned from tank. Warning Note: Never leave the tank gas valve in "open" position" when engine is not running or the bike is in storage.
14. After or before each ride check all mounting fasteners, including head bolts, axle and brakes.
15. Warning Note: Engine lock up or piston seizure due to improper gas / oil mixture will not be covered by factory warranty. This the responsibility of the owner / operator to make sure the gas and oil is mixed correctly.
larry ca
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just so you don't start feeling all alone out there...

based on the little i know, i'd be double-checking intake gasket and tightness, carb to intake connection...we're looking for intake leaks.

re: the main slide/needle...what slot is the circlip on? may make a difference.

just throwing some things out there to check out.

good luck & keep us posted 8)
The "no idle unless full choke" problem certainly sounds like
an intake gasket. Frustrating, certainly, but easily fixable.

Make an expedient gasket out of thin single ply cardboard
(such as a cereal box) and coat with RTV silicone sealent
(or equivalent) and re-assemble. I bet that will cure most of
your problem. The cheap gaskets that came with the kit are
not to be trusted. Be careful.

standard issue