looking for a little bit more torqe lifan 125cc

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darkestskydiver

darkestskydiver

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reno, nv, usa
as the title states i was looking for a lil more torqe from my lifan 125. i will be getting an oko 28mm soon but was looking at a new cam as another option. can yall recomend a cam for this engine that will give me a lil more low to mid power? the engine is all stock other than the exhaust, and soon to be carby. the exhaust is a hand built 40mm with a kxf 450 muffler that will be shortened up by about 120mm. but it sounds killer right now so i have not messed with it yet.
also what gear ratio's are yall running with this engine? i weigh apprx 72kg
 
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ok 2 problems i see straight away...

28mm oko with major mods it might work but with only a cam it will be a pig..

40mm exhaust.. im guessing this is 40mm right down to the head... big no no on small block engines... 30-32mm is about max you want.. 40mm alone will rob you of a heap of torque so your going backwards before you start going forwards...

akunar.com - cam and valve spring package something high lift but low duration should do what ya want.. or jump on a usa minibike store and check some of the TB range of cams..

also heres where you going to get in trouble... you want to add a heap of torque and power but your going to destroy clutches pretty quick..

do your self a favor and spend your money on a gpx125 or a zonger 140 or better yet a z155 or z175..

gear ratios depend on ride style... track or bush..
 
i mostly ride around my house. lots of hills and some flats here and there. also forgot to mention i live at around 1,615m above sea level.
 
first thing, check that there is no over lap between the gasket on the manifold to the head, because i used to have a lifan 125 and that was a problem i found and i just cut out the over lap and it gained a bit more. and also some times there is a restrictor between the carby and the manifold, if so get a rat tail file and go to town on it
 
Clutch on crank? 2-bolt or screw-in tappet covers? Low compression kills the ones with the "good" 2-bolt cover head. Needs compression way before a cam, and the 28mm carb and sewer-pipe exhaust is for engines half-again bigger, as stated below. Or above if you select new up top view;) A 22mm Chi-kuni, 25-28mm pipe and a piston kit will have you cruising effortlessly.


Gear to suit your needs.
Honda50.com Gear Ratio - Speed Calculator


Lifan 27/23 head likes a piston like the 55.5mm Akunar in my jumbo meat hook:
partz038.jpg
 
Yep, low compression, iron jug, big head version, with clutch on crank. $139 for the new TB kit with a domed piston, 57mm alloy jug. Much horseplay will slip the clutch, DrATV springs and TB plates is only $30 or so.
 
yep, save your coin and buy a bigger engine... better bang for buk at the end of the day with the option to mod further..

id go a klx style engine
 
darkestskydiver said:
so would this be good for an upgrade? Dirt Pit Bike 1P55FMJ Engine Cylinder Kit 140cc Parts - eBay (item 180574701335 end time Feb-11-11 20:47:15 PST)
or is there an actual bbk for these engines? i have another exhaust kit that i will be bolting on to see if that helps. and i'll look into a diferent carby than the 28mm. as far as the cam goes what are the dimensions of the stock lifan cam. size and lenght? thanks.
Click to expand...

lol, thought id better answer this..

to use that bore you would have to measure the barrel heights and piston pin size
you also have to see if the cases require boring for the bigger sleeve..

ok a thing about the crank mounted 125 engines getting around..
theres that many different versions its not funny..

its like china factories just use what ever is on the shelf to complete an engine..

varieties of strokes and bore sizes.. 52.4 x 52.4.. 52.4 x 54 and so on.. lol most 125's are actually 116 or 120

if you have a genuine lifan engine most of the engine case bolts will have a lifan logo on them..
 
well it is genuine lifan afaik. all the markings are correct. the engine numbers are correct. and the packing box i got it in had all the lifan markings on it as well as the instructions booklet i got had there logo on it and i had to get it translated to read it. so i am pretty sure it is a genuine lifan. as for the possible machining goes, thats not my concern as i have full acess to a machine shop to do the work in.
i will not buy another engine and spend 300+ on it when i can achive my goals spending far less and a lil of my time.
so sean01 what should my measurment be to use the linked parts kit? i can mic everything out this weekend to verify what i actually have.
 
you may lose a bit of reliability by doing this, but if its what you want then go for it :D
 
yeah there the markings...

and going by your engine number (52) outlines the bore size, so you havent even got 125cc to start with.

you'll have either of these..
52.4 x 54 = 116cc
52.4 x 55.5 = 119cc (more than likely this one)
54 x 54 (1P54FMI)

also exactly how much more power are you looking for?

if you have access to all machining options then order a 1mm oversized piston (or what ever the sleeve will allow without getting too thin) from akunar and bore the cylinder to suit. deck the cylinder or add base gaskets to get around 11:1-12.5:1 and a nice cam and springs and clearance the valves...
oko 26mm carb and happy days

to order a piston you just need to know the compression height (pin to top of piston) and pin diameter(from memory they are 14mm pin)

AKUNAR PRO PISTONS

and to order the cam you need to measure it as well..

please dont over look the clutch..you'll regret it otherwise..
 
yeah the tru cc's are 119. they call it a 125 tho. i dont need much more power just a lil more than what i got. as i said i live in a very hilly area so more trail riding than racing. i'll look into the options you listed as they seem to be what i'm after. thanks.
 
if your only after a fraction more...

remove the base gasket and use honda bond to seal it, but be careful not to block the oil feed hole. this will raise comp a fraction.. base gaskets are worth about .5mm more piston up the bore..
and for more comp again buy a shim style head gasket from akunar (thinner the better) std head gaskets are worth about 1mm thickness, try find a .5mm one.. just check valve to piston clearance

add an oko 26mm or track down an oko 24mm carb...
 
I got a aftermarket cam and valve springs, both brand new im no longer using to suit a Lifan 125. Both from Akunar.

$30 posted for both if your interested (RRP US$74 + post from Akunar)

897c13d6.jpg
 
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