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  1. #1 Superbyke rmr 150cc big bore engine\carb problems 
    C-Moto Noob
    Join Date
    May 2015
    Location
    uk
    Posts
    2
    Hi everyone.. hoping to find some help here... I have a superbyke rmr 125 and have fitted a 150cc big bore kit.

    This one.http://www.ebay.co.uk/itm/151947456016

    With this carb.
    http://www.ebay.co.uk/itm/381298305214

    And this air filter.
    http://www.ebay.co.uk/itm/162063142278

    I have blanked off the egr and completely removed it and added a filter for the breather which was attatched to old air box.

    Now to my problem. The blasted carb setup!!
    The carb originally came with a 100 main jet, I adjusted the air screw to get the idle set and the revs to go up and down quickly and responsivly when open and shutting throttle.
    Great.. no problems. Took a little time but good.
    Test run.. throttle a little baggy at low revs, but moves up 7.5k without too much effort then... bogs out like being flooded or starved.
    So.. I change jet from 100 to 110.. lmao.. the thing wouldn't go past 2k and struggled to pull me along..
    I have now put in a 95 jet from the original 22mm carb that came with the bike.. it can pull to 8k before bogging out and has a little more power in lower gears. Still no where near as much power/pull/torque when it was a standard 125cc.
    Surely I can't need to put in a smaller main jet than the original 125 carb and block needed? To make this bigger cylinder work properly.
    Other posts I have read suggest 110 or 115 main jet.
    Any suggestions appreciated.
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  2. #2 Re: Superbyke rmr 150cc big bore engine\carb problems 
    C-Moto Noob
    Join Date
    May 2015
    Location
    uk
    Posts
    2
    Right.. figured it out. Put original mikuni vm22 carb back on,... 30mm carb is a PITA to tune up correctly.
    I left the original pilot jet in which is a 15 and dropped the main jet to 92.5. I also dropped the needle in the slider down 2 notches. It is now sitting in the middle notch of the needle.
    Please don't be fooled into thinking a bigger cylinder/piston will require an upjet of the carb, mine had to be jetted down and I may even go down to a 90 main once I have it run in properly.
    Have a 16tth front but may change it to a 17.
    So far everything seems to be running well. Much more torque in lower gears and still pulls hard in 5th.
    Not run in properly yet so I'm not sure about top end speed, but am expecting an improvement over the original engine.

    I would like to thank mychinamoto and it's members for the invaluable information contained on this site, without it i would of kicked my bike half to pieces and be walking to work.
    Tony
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