GY6 150cc

Quick Facts and info on GY6 150 Machines

CH - CN - CF 250cc

Quick Facts and info on 250 Machines

GY6 Engine codes

Understanding the numbers

learn how to find what GY6 motor you have.

GY6 150cc Valve setting

How to

Setting the valves on the 150 is easy and should be looked at if your machine is more than a year old, especially if you're experiencing any performance problems that aren't found elsewhere.

Do I have a
150 or a 250?

Bought a used ride and not sure what size motor is in it?
The quickest way to tell if you have a 150 or a 250 is, most all 250 machines will have a radiator and the 150's do not however, there are other ways to tell what you have.
Read below...

Gy6 Motor help in Delta, PA.

Which motor do I have?

CN250 (GK) & CF250cc

Quick Facts

*The CN/CH250 motor is a carbon copy of the 1986 Honda Helix.

*Most of These 250 motors use a 172mm Piston & Cylinder. 4 Stroke.

*Most 250cc vehicles come with a 28mm or 30mm CV carburetor installed stock with around a #125 main jet and a #35 pilot.

*The center hole on the CN250 clutch (Flat to flat measurement) is 26mm.

*The center hole on the CFMoto 250 Clutch is 24mm (Flat side to Flat side)

*The 250 Produces around 19HP and has a top speed of around the high 30's in a Go Kart and high 60's on a scooter.

*Almost All 250's use a DC CDI

*USES 80w90 Gear oil

*USES 10w30 motor oil (5w40 in the manual but 10w30 is universal and works great)

GY6 150cc

motor Quick facts

*The same SIngle Cylinder, Air cooled 4 stroke GY6150cc Chinese motor is found in almost all 150cc Chinese Scooters and Go karts imported into the US.

*Some Common factory Motor names are: Tongjin, Howitt, Tecumseh and many  motor parts are interchangeable between them. Most use a 58mm Piston & Cylinder

*Most come with a 24mm Carburetor installed stock and anywhere from a #105 to a #112 Main Jet and a #35-#38 pilot Jet.

*produce around 9-1/2 hp with a top speed in the low to mid 30's for a Gokart and close to 70mph when installed into a Scooter.

*The kick start shaft is commonly repourposed to hold the exhaust and an external reverse box is added when installed into a Go Kart.

*Go karts typcally use the short case version CVT (16")

*Scooters typically use the Long case version  CVT (18")

*Uses 80w90 Gear Oil

*CAN Use 10w30 Motor Oil (Manual calls for 5w40 but 10w30 is universal and   works great!)

We specialize in adding performance when replacing worn parts!

Knm Garage Go Kart Performance How To

It's Eezy-Peezy and anyone can do it!

Your new machine is actually very basic and most issues are simple in nature.



Chinese Scooter and Go kart Parts, Repairs & Upgrades made easy!


©KidNme llc

Ring gaps are often a confusing and misunderstood part of a re-ring job. There are MINIMUM and MAXIMUM ring gap specifications,which must be observed for the best performance of a new ring set.

Minimum gap tolerances must be observed in order to prevent the ring ends from butting together as the ring expands when the engine approaches operating temperature. Hastings recommends a MINIMUM of .0035 gap per inch of cylinder diameter. Example: 4" (bore) x .0035 = .014 minimum gap.

Maximum ring gap is an important part of ring performance in that too much gap results in lost compression, power loss, and ultimately poor oil control. The following chart indicates the specifications for compression ring gap as outlined by the Society of Automotive Engineers (SAE) as standards for the automotive piston ring manufacturers.

Safe, Recommended Automotive Compression Ring Gap Clearances

Ring Diameter               End Clearance Inspection Limit

1.0 - 2.3624                              0.006 0.014
2.3625 - 2.9524                        0.008 0.016
2.9525 - 3.5424                          0.01 0.02
3.5425 - 4.3299                        0.012 0.022
4.33 - 5.1174                            0.014 0.026
5.1175 - 5.9049                         0.016 0.03
5.905 - 6.8899                           0.02 0.035
6.89 - 8.9999                            0.024 0.041
9 10.9999                                 0.029 0.047

An important fact to remember is that the manufacturers rigidly adhere to these tolerances and that the ring gaps are inspected in gauges accurate to .0001" at the cylinder diameter the ring is manufactured for. Any increase in the diameter of the cylinder is being used in, over the designated size, results in an increase of approximately .003" in ring gap for each .001" increase in cylinder diameter.

In order to check ring gap, the rings should be placed at the lowest possible part of the cylinder (below ring travel area) as this is the portion of the cylinder that is unworn and which the ring is sized for. Checking ring gap in the worn portion of the cylinder will show a gap increase in direct relation to the amount of cylinder wear present. The illustration on the right shows the effect of cylinder wear on ring gap.

This graphically illustrates the effect on ring gap that cylinder wear has. You will notice that the tapered cylinder has .012 wear at the top portion of ring travel, which increases the ring gap .036. Therefore, it is entirely possible for the ring to have .061 end gap in that portion of the cylinder and be within recommended manufacturing tolerance.

For this reason, Hastings recommends a MAXIMUM of .003" wear per inch of cylinder diameter, not to exceed .012" in any case for successful re-ringing. If a cylinder is worn in excess of this it should be re-bored and the proper oversize ring installed. Checking ring gaps can give an approximation of cylinder wear as well as keep you from installing wrong sized rings for the application being rerung.

The Diagram to the right shows effect of .012 cylinder taper on ring gap in four-inch bore.

Checking Compression Ring Gaps

[effect of .012 cylinder taper on ring gap]

250cc Valve setting

How to

Setting the valves on the 250 is easy and should be looked at if your machine is more than a year old, especially if you're experiencing any performance problems that aren't found elsewhere.

Trans Oil Change


Changing your transmissions oil is easy and only needs to be done a couple times......

Motor Oil Change


Changing your oil is the 1st thing you should do and do it often.......

GY6 150cc Oil Change

How to

We use a quality 10w30 motor oil until the motor is broken in (Approx 500 miles or more) then switch to a quality Synthetic.
We also use an 80w90 Tranny fluid.