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  1. #1 BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
    C-Moto Not-so-Noob
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    I own yuki SM 125 (QM125GY-2B with K157FMI engine)
    stock engine wrecked and coudlnt get replacement in my country (Slovakia)
    Fitted Suzuki GZ 125 Marauder engine inside..
    rebuilded it with my mechanic
    GZ 125 Marauder 2000 year bottom end (bought with 12000km on clock, spins easily, no rod play
    used stock k157fmi cylinder and bored to 58.25 and used this piston
    http://www.ebay.com/itm/KR-KOLBEN-KO...pVZ-33&vxp=mtr
    bought suzuki gz 125 marauder head (2001 year) with 12mm sparkplug and 30/26 valves, valves has been grinded againist seat to make perfect seal/seat.. , piston rings were set and installed by mechanic.. and used rocker arms from k157fmi as they were in better shape than ones from used GZ head
    bike had problem putting out more than 75KM/h!! (very low) i could jet it how i could want
    replaced the stock filter with double foam filter, pitbike 38mm exhaust (loud as hell)
    and installed LT230s camshaft used from ebay, bike did around 91-94km/h not tucked in and around 98km/h tucked,, and 105km/h with going behind car, tucked in , and backwind
    now the cylinder is scratched after 8000km (double foam filter and took water in rain..) 9.5bar compression only opened throttle
    going to rebuild it with big bore kit..
    which one do you recommend?
    could this one be used with domed top piston?
    https://www.aliexpress.com/item/BIG-...999.301.1uT0vZ
    my sparkplug is dr8ea
    sprockets are 15/51 (used JT ones), from wemoto.com.. bike felt slow with 16/51 (this combo i used on old engine
    used already once taobao (cssbuy agent) to order items from there, the right hand switch and clutch cable.
    any ideas to make my bike go atleast like stock 100-105KM/h GPS? (using aftermarket speedo calibrated with GPS btw)

    HEAD HAS NO SAI HOLE
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  2. #2 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
    Senior C-Moto Guru humanbeing's Avatar
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    Stock gz (15/45)... Ur's 16/51
    Faster = Smaller rear sprocket http://www.mychinamoto.com/forums/sh...4379#post84379 or make the ratio smaller than those Suzuki (No good to discover trails / Lots of Up-hill...)
    Domed is for 12mm (NGK D...)
    ===
    U already had experience buy via agent ***engtaobao.com offeres good old SAL option https://en.wikipedia.org/wiki/Surface_Air_Lifted *** ...https://item.taobao.com/item.htm?id=37368510898 is maker's direct sale... https://item.taobao.com/item.htm?id=40158406458 had those better rings https://translate.google.com/transla...D80&edit-text=
    Last edited by humanbeing; 05-17-2017 at 01:10 AM.
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  3. #3 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
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    Quote Originally Posted by humanbeing View Post
    Stock gz (15/45)... Ur's 16/51
    Faster = Smaller rear sprocket http://www.mychinamoto.com/forums/sh...4379#post84379 or make the ratio smaller than those Suzuki (No good to discover trails / Lots of Up-hill...)
    Domed is for 12mm (NGK D...)
    ===
    U already had experience buy via agent ***engtaobao.com offeres good old SAL option https://en.wikipedia.org/wiki/Surface_Air_Lifted *** ...https://item.taobao.com/item.htm?id=37368510898 is maker's direct sale... https://item.taobao.com/item.htm?id=40158406458 had those better rings https://translate.google.com/transla...D80&edit-text=
    Thanks for your answer humanbeing!
    yep currently i have domed top engine from GZ marauder 125 2000 bottom end and 2001 head.. (NGK DR8EA sparkplug)

    on chinky (K157FMI which dropped valve) engine i used 16/51, transfered it to the suzuki engine and the engine had not enough power even with the camshaft.. so when i was ordering new chain set (using jt sprockets.. 15/51) and swift heavy duty chain
    CSSBUY offers SAL post. so its okay and have only 4% fee there due reddit

    1st question is which option is good for me without SAI hole (without EGR hole) (picture),, i want silver cylinder without SAI with domed top piston
    there were some horrors with people seizing engine due to big bore kit.. (run shell Advance Ultra 10w40 oil btw.) 6€ per litre fully syntetic

    2nd question.. which are the best rings for the 147cc big bore kit(62mm) ? i guess the 62mm CG150 ones, but i am not sure if the thick, thin ones or what (picture)

    3rd.. due to possibility of slow bike.. could be the reason due to bike needing different ignition timing, is there any better cdi out there? (plug and play or with adaptor.. ) best in mind with rev limit in place or so.. or programable..
    sending some pictures.. have copy of polisport halo,, and suzuki GZ 125 marauder engine on my QM125GY-2B)

    4th are any oil valve stem seals for valves available for my GZ marauder 125 in taobao?


    5th question.. what carb do you recommend.. currently running stock mikuni vm22,, intake manifold enlarged to accomodate the intake hole on head..
    its enlarged from 24mm to 27mm.
    also added picture when i built it year ago.. (the reason of the cylinder scratches are the small fine dust from the valves brushing againist seat to make good seal.. (my mechanic said thats the problem why your cylinder is scratched..).

    the links
    the cylinder

    http://www.cssbuy.com/item.php?url=h...%3D37368510898

    the rings

    http://www.cssbuy.com/item.php?tid=40158406458
    looking for CID or PVD ones..
    Attached Images
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  4. #4 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
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    the piston picture of build..


    15609069_10207983188646307_483017409_o (1).jpg

    the jung cheng head gasket was 1.0mm.. used during rebuild thin suzuki one with thickness 0.1mm..
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  5. #5 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
    Senior C-Moto Guru humanbeing's Avatar
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    [1] Option 2: GN 欧(Euro)一 银(silver)... 凸... Mechanic's theory about full syntetic https://translate.google.com/transla...5082&sandbox=1 12,13#
    [2] PVD type is the best BUT very difficult to find from retail... CID is better than regular... What u need is name brand 62: 1.2/1.2/2.5 (ie. the stone age CG150) rings unlike those T??? kit...
    [3] Check ur rotor http://www.motorfans.com.cn/forum.ph...uthorid=217223 Good old 凸 GS125 (That thingy is shorter than 10mm flat)= Denso 05300 . The
    "4-curves" CDI had one option that similar to this legend aggressive...
    [4] Those thingy are 5.5*11*8.2 (Suzi #: 09289-05018) It's not that expensive in EU, Why TB??? Anyway https://item.taobao.com/item.htm?id=40284472851
    [5] No comment
    ===
    Back to the basic https://item.taobao.com/item.htm?id=35540342426 if worry it will fail...
    Last edited by humanbeing; 05-18-2017 at 05:32 AM.
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  6. #6 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
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    Found the thread with 4 curve cdi... Asked seller if he has one available he said none in stock
    1st will order that 150cc one :) thanks for link..
    2nd contacted the seller.. He didnt tell me if the "CG150 option Phi is 1.2 1.2 2.5 (or got any better link please which are for sure 1.2 1.2 2.5 thickness rings?

    3rd dont understand chinese.. So used the translator to english where i could.. Will measure the rotor tomorrow and let you know..
    4th around 10-12 eur for those seals which is bit steal at official dealer but propably jap part better than chinky
    5th.. Had pz27 on my bike, adjusted float main and pilot jet and it still ran worse than the vm22 (130cc 58.25 piston)
    Special question.. Are the rocker arms same in gz/gn/dr pre 2003 family same as k157fmi? I used the ones from k157fmi as they were in much better shape..

    Thinking about going to pz30 with acc pump or legit vm24/vm26
    You are the real pro humanbeing. Where are you based anyway?
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  7. #7 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
    Senior C-Moto Guru humanbeing's Avatar
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    Maker's model | diameter| thickness | Shop's option | Fits
    ===
    Rocker Arms https://www.bike-parts-suz.com Typed EN125. Result: Part # is the SAME btw old & new
    Last edited by humanbeing; 05-19-2017 at 01:20 PM.
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  8. #8 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
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    Will order the CG150 rings.. the standard ones..
    and thanks for the site. its amazing
    got paypal? wanna donate for help
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  9. #9 Re: BIG BORE KIT, most modded QM125GY-2B ever propably?, need some help. 
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    Quote Originally Posted by humanbeing View Post

    Maker's model | diameter| thickness | Shop's option | Fits
    ===
    Rocker Arms https://www.bike-parts-suz.com Typed EN125. Result: Part # is the SAME btw old & new
    talked with seller.. he has only egr version (even trough choosed gn convex euro.. )
    he said its compatible.. but it looks pretty weird when you are assembling it as i have currently also egr cylinder.. and non egr head.. haha
    and its just been shipped..
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  10. #10  
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    Quote Originally Posted by SanoShaker View Post
    talked with seller.. he has only egr version (even trough choosed gn convex euro.. )
    he said its compatible.. but it looks pretty weird when you are assembling it as i have currently also egr cylinder.. and non egr head.. haha
    and its just been shipped..
    Plug n blank that off
    Not needed makes no difference then if it ever actually did


    Sent from my iPhone using Tapatalk
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