Import Motor FAQ - Long Stroke Mills

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Import Motor FAQ - Long Stroke Mills

This is a discussion on Import Motor FAQ - Long Stroke Mills within the Chinese/Import Minis - General Discussion forums, part of the General Talk category; This FAQ is for all Import motors running a stock stroke of 52mm or longer. As you track down relevant info, post to the thread ...

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    Import Motor FAQ - Long Stroke Mills

    This FAQ is for all Import motors running a stock stroke of 52mm or longer. As you track down relevant info, post to the thread and I'll add it to the FAQ. For shorter stroke motors, there will be a separate FAQ.



    Identification: There are many many different importers bringing over either crate motors, or entire bikes under a variety of labels. In most cases, the actual 'brand' of the motor can be traced back to a small group of producers in China. Generally speaking motors of a particular model number from a given producer will stick to a single common specification, so once you've identified your motor you can feel confidant ordering parts based on that ID.



    Lately though with the larger displacement motors we're seeing variations even within a particular make and model of motor. Motors where inconsistencies have been observed that are more than just normal design updates over the life of a product will be noted. On these machines, you'll need to measure your machine specifically to determine which parts are appropriate.


    Lifan - One of the most well known import brands. Like most manufacturers anyone can have a motor produced by Lifan with their name on the side, and some people buy Lifan side covers to slap on lessor motors so don't use those labels as reliable identifiers.
    Identifying Marks
    Known Lifan Motors
    * SDG Pro Mini's '125' motor is basically a Lifan Monster 120 motor. This unit is a bit unique in that Lifan assigns SDG a unique model number rather than using their standard model number schema.
    Jialing - Made 'famous' by GPX / Pitster Pro importing them with much fanfare starting in 2005.
    Identifying Marks
    Known Jialing Motors
    * GPX 125
    Zongshen - Runner up to Lifan and Jialing for brand recognition.
    Identifying Marks
    Known Zongshen Motors
    * RCM bikes in 2005 and 2006 utilized Zongshen powerplants.
    Loncin - Ebay favorite, no known 'big' import brands use this make of motor in their bikes, but many smaller brands do.
    Identifying Marks
    Known Loncin Motors
    Ducar - Less seen than even Loncin, typically found on Ebay.
    Identifying Marks
    Known Ducar Motors
    Faddybike - Produced in Thailand as a clone of the Honda Nice/Wave powerplant.
    Identifying Marks
    Known Faddybike Motors
    Motor Specs: There are a few basic stats that help determine what parts will fit which motor. They also can help determine when you can 'borrow' bits from other motors to use as hop ups by cross referencing other machines with similar base specs.



    To stay consistent, a few measurements will be based on the following giudelines when there is a chance for ambiguity:
    Piston Pin Height: Measure from the TOP of the pin hole to the top of the outer edge of the piston. Some people measure to the middle of the pin hole, but this method allows or a direct read with a ruler or set of calipers making it simpler for others to check and compare.



    Stud Spacing: Until a better way of quantifying stud spacing is developed, one motor will be designated as the 'reference' mill for a given stud pattern. All motors that are compatible will list that motor under stud spacing.


    Lifan 'Monster' 120


    Brand: Lifan

    Bore: 52.4mm

    Stroke: 55.5mm

    Piston Pin: 14mm

    Piston Pin Height: 12.8mm

    Cylinder Height: 79mm

    Stud Spacing: Lifan Monster Standard

    Clutch: 4 disc primary mount

    Oil Pump: Direct crank drive

    Transmission: 4 speed, 1d3u or 4u depending on shift drum used

    Countershaft: Coarse 17mm

    Start in gear: Yes

    Head: 27mm intake, 23mm exhaust, Honda CRF50 style cam
    Zongshen 120


    Brand: Zongshen

    Bore: 52.4mm

    Stroke: 55.5mm

    Piston Pin: 14mm

    Piston Pin Height:

    Cylinder Height:

    Stud Spacing:

    Clutch:

    Oil Pump:

    Transmission: 4 speed

    Countershaft: Coarse 17mm

    Start in gear:

    Head: 27mm intake, 23mm exhaust
    Zongshen 124


    Brand: Zongshen

    Bore: 54mm

    Stroke: 54mm

    Piston Pin: 14mm

    Piston Pin Height:

    Cylinder Height:

    Stud Spacing:

    Clutch:

    Oil Pump:

    Transmission: 4 speed

    Countershaft: Coarse 20mm

    Start in gear: No

    Head: 27mm intake, 23mm exhaust
    'GPX' 125


    Brand: Jialing

    Bore: 52.4mm

    Stroke: 57.5mm

    Piston Pin: 13mm

    Piston Pin Height: 13mm

    Cylinder Height: 79mm

    Stud Spacing: Lifan Monster Standard

    Clutch: 5 disc primary mount

    Oil Pump: Direct crank drive

    Transmission: 4 speed, 1d3u or 4u depending on shift drum used

    Countershaft: Coarse 17mm

    Start in gear: Yes

    Head: 23mm intake, 20mm exhaust, uses 'E22' style cam, short
    Transmissions: There are a few variations on a common theme floating around in the gear boxes of various motors. Most all import big displacement mills run a 4 speed box with either an international shift (1d3u) or all up shift pattern.
    Jialing
    Gear Ratios
    1st: 3.181

    2nd: 1.705

    3rd: 1.238

    4th: 0.958
    Shaft Sizes
    Lifan 120/125
    Gear Ratios

    Shaft Sizes
    Main Shaft: 17mm clutch side, 12mm sprocket side

    Counter Shaft: 14mm or 15mm clutch side, 17mm sprocket side
    Cams: Remember to verify valve to piston clearance, and valve to valve clearance whenever swapping cams around.



    There are many cam specs HERE for comparison amongst the various offerings. You can thank Cyclerider for gathering most of that data.


    Jialing 'small valve' head - Uses 'short' E22 style cams with a 3 bolt sprocket. Note that it's been reported later heads have altered geometry, causing valve to valve contact with long duration cams. G1 and G2 Crower grinds are reported to work with both older and newer batches of the Jialing small valve head. As yet no external method of telling old vs new heads apart has been reported. VERIFY valve to valve clearance before running an aftermarket cam!Lifan 'Monster' big valve head - Uses Honda CRF style cams. Note, it normally uses a 3 bolt 32 tooth cam sprocket, Honda cams use a 2 bolt pattern. If you use this head on a motor with a 16 tooth crank sprocket, you will need to source a 32 tooth 2 bolt cam sprocket to use Honda cams. Periodically check your cam sprocket for signs of excess wear where the cam cover thrust button contacts, or the inside thrust tab rubs.
    Piston Kits: Yeah, right, you're going to leave YOUR's stock...



    Countershaft Sprockets: It used to be simple, you just ordered front sprockets for an old Z50 and they'd fit... but some motors started shipping with larger countershafts, with require different sprockets that don't seem to match any existing motors. See which shaft type your motor takes in the specs section, then check out some of the available options.
    Coarse 17mm - Aka old Z50Coarse 20mm - Lifan and Zongshen 54 x 54 motors
    Dr ATV
    Common Issues: What to look forward to with your new motor, along with preventative steps or post gotcha fixes.
    Clutches
    Primary Shaft Mounted Manuals - There are two varieties you'll see, 4 disk and 5 disk, with Jialing being the only one shipping a 5 disk setup at this time.
    Slipping Clutch - Put heavier springs in. The most common suggestion is to get a set of clutch springs for a Honda 1999 or later TRX90 and swap them in for better clutch feel and more grabbing power.



    5 disk upgrade - Some have sucessfully transplanted a 5 disk clutch stack from a Jialing to other motors that initially had 4 disk setups. This requires modifying the clutch basket, removing material from the bottom of the tab cutouts so the new stack will fit in.

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    Thread cleaned, all info gleaned and added to the above.



    Anyone got more info to add?

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    Outlaw Powersports's Avatar

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    Kurlon, great compilation of information!!!



    Now if we can just get some dyno's done on each of these motors after mods, that would be great. I am working on getting the GPX motor with the Lifan 140 head dyno'd.

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    Macka's Avatar

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    Lifan has a 124cc same as Zongshen. Same specs as you have listed so far for the same cc zonger. I will be able provide more specs in the near future.

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    Some more on the Zongshen:



    Identification:

    From what I have seen, all the Zongshens engine numbers start with ZS, in my case, ZS154FMI for my 125cc, then below it the identification number.

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    Just got a new Lifan 125 Monster



    127.1cc

    9.5 hp

    55.5mm Stroke

    54mm Bore

    23mm Exhaust Valve

    27mm Intake Valve



    Start in any gear with 4 up transmission

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    Winston, have you actually measured the bore and stroke on that motor?



    (And for reference, the Lifan 'Monster' tag refers to a specific Lifan 120 motor, all others are not monsters despite similar specs or bottom ends.)

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    No but here is a link to where i got it from



    http://www.britishamericanmotorsport...n/lifan125.htm



    Also on the side of the engine is 137cm3 dont no if that is any help

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    So, fun question is weather or not that bore kit was installed at build time by Lifan or by the shop selling the motor... If you get a chance, crack into that mill, get some pics, and take some measurements. : )

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    kurlon,

    Do you know the history of the 120 or a link, whats a honda nice, this is a chinese clone of the honda?

    Here is my lifan 120 or 125 piston specs





    40mm tall

    52.4 dia

    14mm pin

    pin center to dome top 22.5mm

    pin center to skirt 17.5mm

    pin center to oil scraper 8.25mm center to center

    pin center to oil ring 12.25 mm

    pin center to compression ring 15.25 mm

    the valve relief are 3mm deep

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    Unfortunately I don't have the history of the Lifan mills.



    The Honda Nice is a motor Honda had built in Thailand for scooters in Thailand that have since been discontinued. It's a popular motor to build because it's damn rugged, easily builds out to 160cc, and parts are still available direct from Honda. The downside, you generally have to get one that was used in Thailand and 'rebuilt' by one of the local scooter shops who don't use what we'd consider best practices. So after spending a large chunk of change to get one, you have to turn around and spend more to bring it back to spec.

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    Kurlon here are con rod specs for the 55.5 x 52.4 motor.

    25mm x 39mm rod pin.

    14mm piston pin.

    100mm rod length center to center.



    you got a gpx rod, need to know the dims?



    What about the piston height, pin to dome top?

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    Quote Originally Posted by Kurlon
    So, fun question is weather or not that bore kit was installed at build time by Lifan or by the shop selling the motor... If you get a chance, crack into that mill, get some pics, and take some measurements. : )




    I bought one Lifan B/Valve kick in gear engine (1P52FMI) with 124 cc on the cylinder and pulled it down to find that it had a 52.4 bore x 55.5 stroke (119.73590666161965 cc) The output shaft has a 17 mm coarse spline :



    and another Lifan B/valve kick in gear engine (1P54FMI) with 138 cc on the cylinder that is 54 mm bore x 55.5 stroke (127.15965846442622 cc) :



    and I also have another Lifan B/valve crank clutch motor (1P54FMI) that has 138 on the cylinder , that I suspect is a 54 bore x 54 stroke (123.72291093836067 cc) but I'll be able to find out now (thanks to the info in this thread) , by checking the diameter of the countershaft .



    I checked the countershaft and it has a 20 mm coarse spline .



    Apparently , they have a taller 1st gear ratio than the kick in gear Lifans . Here are the specs of them :



    Specifications:

    Single cylinder, 4-stroke, 2 valves, OHC racing head, air cooled, 125cc

    Bore x Stroke: 54mm x 54mm, this is a 'square' engine for best balance between power and torque

    Valve Sizes: 27mm intake, 23mm exhaust

    Displacement: 123.7cc

    Compression Ratio: 9.47:1

    Gear Ratios: 1st 2.833:1, 2nd 1.706:1, 3rd 1.238:1, 4th 0.958:1



    This is the same as the (1P54FMI) "138" Lifan crank clutch engine and has the same type of flywheel cover !

    http://cgi.ebay.com.au/ws/eBayISAPI....ype=osi_widget



    They are also selling 140's with 55 bore x 59 stroke on ebay OZ :



    http://cgi.ebay.com.au/ws/eBayISAPI....8492&rd=1&rd=1

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    Interesting, where did you get the gearbox data? That's a much closer ratio setup that I'm using to seeing in an import mill.

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    hey i have the same Lifan big valve with the 124cm3 on the cylinder that turned out to be a 52.4x55mm, but the funny thing is, my engine # is 156FMI. I dont think that you can trust any of the markings on the cylinder and apparently not the model # either. oh well.

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