need some advice lifan 140cc cylinder heads

[myinnerrotorkits]

hi i have some lifan140 alloy heads and heavy black 140 cylinders from last year. i am a rookie for engine problems and i just wanna use another higher cam to make engine much more power,i only can do simple modification, dont know whut cam can fit the cy head? but no any other modifications!! another questions: whut good crankcase can fit this head and cylinder. need help!!
thanks in advanced

 

[corey58]

u an pitbike wolesalers but dont no things like this???

 

[no_crf50_here]

is it just me or does it seem like he is doing market research or something?

 

[corey58]

yer dose seem to be the case

 

[MasterSpoon]

market research may be a good thing
we are always finding different problems with these bikes or things that could have been done better originally so I don't mind. No idea on what to use tho.

 

[Mack]

Heres a question for you. How many and how much can you supply Lifan 140 heads? The barrels are useless.

 

[Dirtrider]

Are the lifan 140 heads the same as the 120 big valve heads?

 

[Mack]

Pretty much same spec, just slightly different casting.

 

[Dirtrider]

So are the 140 heads any better than the 120 and will the cam and valves all swap over?

 

[myinnerrotorkits]

not same

not same the valve size is different and the cam is different

Are the lifan 140 heads the same as the 120 big valve heads?

 

[myinnerrotorkits]

Mack

HI Mack
i only want to sell them at cheap price to clear stock before 30th Jan
PM or MSN NP

Heres a question for you. How many and how much can you supply Lifan 140 heads? The barrels are useless.

 

[myinnerrotorkits]

i never try this before but i want to do it by myself not workers

u an pitbike wolesalers but dont no things like this???

 

[themountain]

whats soo different on the cams??... they are crap anyway....so, how much for a unit??

 

[Mack]

They increased the lift on both lobes but majorly on the exhaust. They must've figured out like we all have, that the engines gain big with improved exhaust flow.

 

[Dirtrider]

What valve sizes do the 140 heads run?

 

[themountain]

They increased the lift on both lobes but majorly on the exhaust. They must've figured out like we all have, that the engines gain big with improved exhaust flow.

the few I checked lately were all the same ....anyway if you got this engine its the first thing which have to go

 

[myinnerrotorkits]

valve size

24/27 it comes with complete cam,piston and rings,bracket and valve complete. normally at 28.0USD

 

[Cactus Jack]

the few I checked lately were all the same ....anyway if you got this engine its the first thing which have to go

140's use the long cam with a 35 mm and 32 mm bearing and the cam sprocket flange is pressed on after the big bearing is put on .......

120 BVH's run a Honda type cam with a 42 mm bearing and a 32 mm bearing .... the sprocket bolts directly to the end of the cam ... They don't have a compression reducing squish ring around the combustion chamber like 140's have ....

I (think) I saw Macks pics of the 140 cams ages ago when he first pulled a new one down and he said they have higher lift and duration than normal lifan cams ...... I'm sure he said they have 6.6 mm lift .... plus the valve springs are better ....

I bought what is supposed to be a Sachs Madass cam off JDM Scooters a while back and it has 6.3 mm intake lift and 6.7 mm exhaust lift ...... I bought it for a Loncin 120 but it fits the 140's .......(71.5 mm long from cam sprocket face to outside the bearing on the other end and 73.5 mm overall) I've got no idea on the duration etc .... It's got CQ 67 stamped on it and doesn't have the anti kick back device ...... any idea on what it is ? It has a heap more duration on the nose than a stock Loncin cam ....

What are the specs on the 140 race cam you got Mr Mountain ???? ie duration @ .050" ....... what lift etc ?

 

[tubes380]

how does the anti kick back actually work???
i have recently installed a big bore kit and fully worked head and the cam didnt have the kick back device on it, and now itll kick back every now and then, im amazed it hasnt broken something.

 

[Cactus Jack]

When you turn the cam clockwise (backwards) , there is a flat spot , then a reverse operating cam on the pressed on anti kickback mech which acts to lift the exhaust rocker slightly , opening the exhaust valve and letting all the damaging compression and combustion force escape out of the exhaust port rather than force the crank backwards and smash the kick starter gears or ratchet mech ...

When I pulled the head off the Loncin 120 I noticed that the exhaust valve was being held off the seat slightly . I thought the exhaust clearance might be wrong or the valve stem had seized in the guide or was bent but when I moved the cam it popped shut and the lash clearance was right . The lobes weren't holding the valve open either since the rocker pads were on the base circle ....... it was the anti kickback cam doing its job .......