Midbike FAQ

Thanks to Joe Lanza and others for putting this together.



MIDBIKE TUNE TIPS.

(These tips are mostly for X1/X2's but all midbikes are almost the same.)

1) OUT OF THE BOX...

when you fist get your X1/X2/cateye it will be, I’m sorry... a piece of junk the mechanics at GSMOON in china are just slapping these things together and shipping them out but with a little work you will have an affordable GP racer.

2) HARDWARE PREP

A)remove all plastic body fairings,
lets start on the right side front ,
B)remove each bolt one at a time so you don’t forget where you were (don't take the bike all the way apart unless you have the memory and skill to put back together)
C)add some locktite 242 medium to each bolt (available at any auto parts store ((*WARNING*do not use loctite red!!! this is a permanent loctite and you will thrash your hardware when you try to remove it ))
D)put it back in, tighten (do not over tighten! the stock hardware is not the greatest, its easy to strip or shear )on our race bikes we have replaced all our hardware with American made stuff
((((*WARNING* do not use loctite around stock break levers or plastic fairings it will melt away the plastic only use on metal.))))

Go all the way around bike a make sure it's all tight .


3) WIRES

we took off all the lights on our race bikes but if you still have all those wires use tie wraps to keep them up around the gas tank and off the engine or you could melt them to your engine and/or pipe and have a real bad day

4) FUEL OIL

Any good synthetic oil. Remember, generally, the more it costs the better the quality. I said generally.


5) GAS MIX

with the X1 or X2 believe it or not with these low compression weed wacker engines, regular pump gas 87 octane with a mix of 20:1 will give you max performance

6) CVT OIL

on the X2 there is an oil service fill and drain bolt on the CVT transmission the biggest bolt on the top of the CVT case is the fill and the biggest bolt on the bottom is the drain. Use 70w90 gear oil

7) CHAIN LUBE

Might I suggest the use of chain oil versus chain wax/chain grease. Just put the oil on a paper towel and just lightly coat the chain with it.

8) IS YOUR STOCK CHAIN TOO TIGHT?

the stock X2 with cvt, chain is way too tight
you want to have at least 1/2 inch play up and down (total play 1 inch) the tight chain puts a heavy load on your cvt output shaft and could damage your output shaft seal !!!on our race bikes we had to add a couple links, especially if you have a larger than stock sprocket

9)AIR FILTER

the stock filter is just a piece of foam just use soap and water to clean, dry and reinstall

if you put oil and gas in it the gas will clean ok and evaporate but the oil will stay on the filter attract dirt and choke the engine. I never recommend using gas to clean anything too dangerous.

Some aftermarket racing filters require a type of oil on the filter element i.e. K&N filters but don’t do it on the stock one...let it breathe.

K&N filters require their filter oil. Remember, DON'T OVERDO the oiling of the air filter! Just needs a tiny bit.

As for me, I personally feel the oiling of the filter attracts more dirt so therefore I use a dry one. ADA Racing is one to be exact.

10) SPARK PLUGS

Non-Projected Type Tip (regular) Plugs:
(Left to Right: hot to cold)

NGK: BM6A, BM7A

Nippon Denso: W20M-U, W22M-U

Bosch: WS8E, WS7E, WS5E

Champion: CJ8, CJ6

AC Delco: CS45, CS42, CS41, CS40

Motorcraft: A7NX, A3NX, A2NX

Autolite: 235, 254, 255, 253
(credit to zero4 for the info)


Platinum plugs are not all they everyone says they are. The only thing about Platinum plugs is they last longer. COPPER conducts electricity better than platinum does.

On another note, I wouldn't go with too hot of a plug (higher heat range) since the engine is air cooled to begin with. Don't want to have too much heat in the tiny engines.


11) Starting YOUR X2

you have to hold the rear break and then push the start button. Make sure you have a full charge on the battery.
pull start = make sure your key switch is ON and close the choke once the bike starts open the choke


12) STOCK CARB TUNE

ok this is a little work I hope I don't lose anyone

a) start engine and warm it up. (2-5 min)

b) have someone lift the rear wheel off ground or use a bike stand to hold bike up off the ground.

c) with short controlled burst of full throttle, turn the air screw IN (rightly tightly, clockwise, etc.) until you reach MAX RPM (listen to the revs- whine it out) Don't worry about turning the air screw in too far, once you go in too far the RPMs will slow down, that’s when you back it off until you reach MAX RPM again.
This will work at any elevation.

13) CVT SLIPING?

http://www.gokartsupply.com/340ser.htm

I sanded my pulleys with 400 grit sandpaper, it hooks up much better now.

14) FRONT FORK ADJUSTMENT

ok you see the nuts on the bottom of your forks these are the lock nuts for the fork tension adjustment screw.
(((They should be the same on both sides)))

To adjust you need to remove front wheel and spin tube.
If you want a harder front end let the threads stick out about an inch.
If you want a softer ride let the threads stick out about 1/8 or 1/4 inch.

If they are not the same on both sides you can damage the break rotor and get bad wear on the front tire use a ruler or some type of measuring devise to make sure they are the same on both sides.

15) BREAK SERVICE

The best upgrades and fixes you can do to your brakes are:

1. Remove the rotors and debur and clean the surface where the rotor mounts to the hub. Clean rotor itself with steel wool and isopropyl rubbing alcohol or acetone to remove any oils. Reinstall rotor (without touching it-oil on pads or rotors leads to poor brake performance) with new pan head or countersunk rotor bolts with blue loctite (NOT RED), and tighten in a criss cross patter (i.e. bolt 1, 4, 2, 5, 3, 6 [assuming 6 rotor bolts numbered in a clockwise fashion) to the correct torque. ($5.50 for locktite and real bolts)

2. Go to you local bike shop and buy MTB high leverage brake levers (for "V" type brakes or specific mechanical disc brake levers) and brake caliper shims (thin, usually 1/100 of an in. washers) ($30 from shop, cheaper online [www.mtbr.com or www.pinkbike.com for MTB classifieds)

3. Buy MTB Cable housing and new cables, metal cable ferrules and end crimps ($15~$25)

4. Install new brake levers (TRASH THE OLD ONES because they suck) and cut housing to appropriate length, but try to measure the cable housing and so the MTB shop can cut with a special tool as to not pinch the ends of the cable housing which will result in poor cable retraction and ****ty brake performance)

5. Unbolt the caliper from the mount and remove pads. Clean pads thoroughly with either motorcycle specific brake cleaning solution, or a 5:1 mix of hot water and dawn or straight acetone then reinstall pads (without touching again). Install new brake lines etc, and fasten loose dangling lines to frame / suspension with zip-ties (but not too tight because of turning and suspension movements, just enough to secure the lines in place). Replace bolts and use new shims to position the caliper so that the pads are about 1~3 mm (depending on brake lever pull preference) away from the rotor itself on both sides. Tighten caliper and fine tune brakes with barrel adjuster on brake lever itself as the cable stretches during its break-in period, and now you will have perfectly functional, STRONG brakes that will stop you.

16) RACING PARTS LIST

I recommend... a racing filter, racing carburetor, tuned race pipe.
2 stroke engines need some back pressure. To get the most performance...


17) X2 DIGITAL SCHWIN SPEED (to get accurate MPH reading)

40.75 inches = 1035 mm is what I chose.

With this # my top speed is 36.7 on flat.

The actual # may be around 40-40.25 if you factor in the "flat spot" or contact patch of the tire. Tire pressure/temp may even be a factor if you want to get precise. I just wanted a base line to measure by.

Thanks to bmarley5780

http://www.pocketbikeplanet.com/images/icons/icon1.gif How to: Hp Carb Tuning. Thanks to someone

Rich: Rich means a lot or in this case more than perfect. (example): If your coffee is too sweet, it is to rich with sugar. If your engine is running rich, it is getting to much fuel added in with the air that the engine is bringing it.





The H.P. Carb includes 3 adjustment screws. These are the idle adjustment screw, low throttle adjustment screw & high throttle adjustment screw. Some people call them the Low speed & High speed screws, but they actually operate based on throttle opening not engine speed.

Idle Screw: The idle screw keeps the throttle slightly open allowing enough air to pass for the engine to idle. Turning this screw in or clockwise allows more air to pass. Turing it out or counter-clockwise decreases airflow.


Counter-Clockwise = less air = slower idle.

Low Throttle Screw: This screw adjusts the amount of fuel added to the air passing through the carb at partial throttle, or up to 1/3 throttle openings.

High Throttle Screw: This "T" Screw adjusts the amount of fuel added to the air passing through the carb from 1/3 throttle to full open.

NOTE: The fuel added by the Low Throttle Screw is still being added at 1/3 to full open. Adding more fuel with the Low Throttle Screw will affect the High Throttle mixture slightly



In order to begin tuning your carb you must first get the engine started so you can listen for Rich or Lean mixture. We recommend these initial settings to start with:

Idle Screw - All the way clockwise
Low Screw - 1 1/4 turns out (counter-clockwise from closed)
High "T" Screw - 2 turns out (counter-clockwise from closed)




Step 1: If you just installed your H.P. Carb Kit. Push the primer until fuel can be seen returning to the tank in yellow return line. (Primer Note: The primer brings fuel from the tank to the carb. Priming the carb not the engine. Raw fuel is not actually being pumped into the engine. Pumping will not help start a cold engine).

Step 2: If the engine is being started for the 1st time with an H.P. Carb, we recommend you pull off the filter and place your finger over the carb opening so no air can pass. Now pull the pull start. After each pull check to see if your finger is wet with fuel. Once your finger is wet, the engine is ready to fire. Hold the throttle 1/2 to wide open* and pull start. Once the engine starts keep it running at the lowest possible RPM. (* without holding your finger on the carb)

Step 3: Warm the engine up all the way. When you are sure it is warm let off the throttle to see if it will idle. If the engine idles slow, chutters & dies then turn the Low Throttle adjuster in 1/4 turn and try again until it idles steady.

Step 4: Once the engine idles steady, use the low throttle screw to get a slow chuttering idle. If the engine slowly chutters and dies, then it is to rich and the low throttle screw must be turned in, to lean the mixture a bit (1/8 to 1/4 turn). If the idle speed gets too fast with the leaner low throttle setting use the Idle screw to get a slower idle speed. The ideal low setting is as rich as possible without loading up (Chuttering & Dying). Once the low throttle mixture and idle speed are set, you are now ready to move on to the High Throttle Adjustment.

Step 5: The object of High Speed adjustment is to obtain the highest possible RPM under load with the richest possible setting. The richer you can keep the mixture while still getting peek RPM the better. The engine will accelerate, it will live longer, run cooler and respond better. Just adjusting the high throttle screw for max RPM on the kick stand would leave the engine very lean and when the engine is under load it probably won't accelerate well at all and could seize.

Instead, start rich and lean the mixture out in small increments (1/8 of a turn). Testing each new setting under a load. Once the acceleration starts to suffer, you have gone to far. (Go back 1/8 of a turn). It is better to depend on cylinder porting to get peak

RPM than on ultra lean mixture settings. Optimum settings for typical stock engines is about 1 1/8 to 1 3/4 turns out.



Problem: Engine Chutters at full throttle and doesn't rev high.
Solution: The "T" screw is to far open. Close 1/8 turn and test under load until acceleration suffers and then open 1/8 turn. NOTE: Engines with stock porting tend to chutter at high RPM.

Problem: Engine bogs from low speed.
Solution: The "T" Screw is to far closed. Open it 2 or more turns and tune for chutter. NOTE: Worn parts, tall gear ratio with heavy porting, high intake duration, restricted exhaust and low cylinder compression can cause low speed bog.

Problem: Engine idles but slowly dies.
Solution: The low speed screw is to far open. Turn in 1/8 turn at a time until idle cleans up. If idle speed is to fast after adjustment slow the idle down using the idle screw.

Problem: Engine idles smooth but runs poor under load unless throttle is full open.
Solution: The low speed screw is to far in. Turn idle screw all the way clockwise and set a low idle using the low throttle screw.

Problem: Engine idles fast and stalls when you try to slow idle speed down.
Solution: These are the symptoms of an intake leak. Go-Peds® usually leak at the manifold to cylinder gasket. Make sure the carb mount screws arent' going to far through the manifold and causing an air leak. Screw marks or cuts in the gasket are a tell-tell sign of screw interference. You can check for leaks with the ped running. Spray WD-40 around the manifold, if the idle speed changes you have a leak.