Just got some specs on my 138cc lifan engine.

[liamisace123]

Originally Posted by physco_nutcase_danny

the lifan 140 has 140cm3 stamped on the barrel and is a kick in gear gearbox..youve got a non start in gear gearbox which is a 125 gearbox..they made a 138 kit for that engine..genuine lifan 140 has a different clutch cover to the one you have because the clutch is more central to the engine rather than at the front...

were can you get these from?

[physco_nutcase_danny]

Originally Posted by liamisace123

were can you get these from?

cylinder barrel http://cgi.ebay.co.uk/Motocross-140c...3A1%7C294%3A30

piston kit http://cgi.ebay.co.uk/motocross-138c...3A2%7C294%3A30

if your going to put this kit on a 125 non kick in gear engine you will have to bore out the little end .5mm on the conrod because the gudgeon pin for this piston is .5mm wider than the 125 piston gudgeon pin.NOT A DIRECT SWAP..barrel will fit no problem just bore out the little end..

you can fit this kit on the 127 kick in gear engine no problem..depends what engine you have..

[Mick]

As far as i know my cyclinder is infact 127cm3, With a fake 138cm3 stamp.


Would the barrel and piston you have stated above bring it up to 138cm3?

[physco_nutcase_danny]

Originally Posted by Mick

As far as i know my cyclinder is infact 127cm3, With a fake 138cm3 stamp.


Would the barrel and piston you have stated above bring it up to 138cm3?

yes it would make the 125 into a 138 but you would need to bore out your little end on your conrod to take the gudgeon pin for the 138 piston.

you need to strip your top end off and measure your piston diameter and compare the sizes to the link above.if its the same size then you have a 138 already fitted and the little end must of already been bored out.if the piston is smaller then there must be a mistake on the stamping of the barrel..which ive never come across before..you will probably find you have a 138 kit already fitted if it states that on the barrel.worth taking apart and measuring so you know what size it is for a fact.

[Mick]

Turns out my engines 123cc, As its non kick in gear.

the 138cc lifans that kick in gear are infact 127cc.

Read below to see why.

Who knows ????? With chinese engines nothing is definite ...... We have a 156FMI Lifan (Mojo Super 120) . We pulled it down to port the head and check the piston size to see if it was 56 mm ...... but it was only 52.4 mm (52.4 mm bore x 55.5 mm stroke). It said 120 cc on the cylinder and it WAS really 120 cc . The 2nd and 3rd numbers are supposed to be the bore size .......

Then I bought a Lifan Super 125 kick in gear motor and pulled that down to find it has the exact same 52.4 mm bore x 55.5 mm stroke (120 cc) despite having 125 cc cast on the cylinder . After that we bought a DHZ 138 with the non kick in gear motor . The start in gear 138's turned out to be 127 cc (54 mm bore x 55.5 mm stroke) yet they have 138 cc stamped on the cylinder ........so I assumed that our "138" engine was a 127 ........ but now according to Le Garage ....... it's possible that those "138" non kick in gear engines are actually only 123.7 cc if they only have a 54 mm stroke crank ......... I know for dead certain that 138 stamped cylinders have a 54 mm bore because I bought a new Lifan "138" cylinder kit and measured it ...... but to make 138 cc the stroke would need to be 60.26 mm .

We ended up buying a 1P55FMJ Lifan 140 to put in the "138" bike and it has been proven (by people pulling them down to check) that they are genuine 140's ......

The ONLY way to know for sure with the engine assembled would be to get the piston to bottom dead centre just before the compression stroke (both valves shut) with the spark plug removed and fill the bore to the top with oil until it comes out of end of a rubber hose that's a tight fit in the spark plug hole . Then bring the piston to top dead centre with the hose draining into a cc measuring flask . The amount of oil that gets pushed out into the flask will be your actual true cc capacity .