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Help Needed

Discussion in 'Site Discussion' started by Matthew Worrall, Feb 22, 2020.

  1. Matthew Worrall

    Matthew Worrall

    Current Bike (Optional):
    My bike
    License Currently Held:
    UK Provisional (CBT)
    Need help please I've put an 180cc bore on my Yamaha and now it stars but is not ticking over right timing is fine all marked up any ideas would be appreciated
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  3. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    have you adjusted the fuelling to match the new cylinder size?
  4. Zedfragg

    Zedfragg Member

    Location:
    Essex
    Current Bike (Optional):
    Yamaha R1 2002 (5PW)
    License Currently Held:
    UK Full Bike
    Are you talking like a rough idle?

    - Make sure all pipes are attached to the airbox.
    - Make sure your power commander is set up correctly.
    - Also, if you did this yourself, make sure that the gaskets are all solid. Don't be using that liquid gasket crap.
    - When was the last time you had a valve clearance? (It's a long shot but changing the bore, you did do the valve clearances right? I'd also expect the clearance levels to be adjusted slightly given the change in bore size.)
    - Have you done a compression test on the cylinder?
    - Are you using an after market set of pipes and exhaust? If not, I'd probably look into one that can handle the additional flow as back pressure will kill the engine with stress eventually. The stock exhaust on a YZF-R125 always felt like cheese to me, especially with the converter being so poorly welded)

    Rough idle is normally caused by one of two things.

    - You/the mechanic screwed something up in the air pipes (Vacuum, routing, pinched pipe etc)
    or
    - You/the mechanic screwed something up in the fueling system (mapping, idle screw etc)

    ... Oh and last one, make sure you have the license to ride a 180cc.

    If you want to squeeze an extra 10mph out of a small machine, you would have been better off with a 2t to be honest. (Especially given the cost of the parts, the REQUIRED extras like remappers and exhausts and the additional maintenance and eventual burnout of the engine as the valves, rods and gears will be under additional pressure).
    I dunno how comfortable I would have been with a 180 bore in my YZF-R125.
  5. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    >> Need help please I've put an 180cc bore on my Yamaha and now it stars but is not ticking over right timing is fine all marked up any ideas would be appreciated

    a 180cc kit will need the fuel adjusting by about +40%, how are you achieving that? When I fired my 180 up on the 125 map it ran but only very rough. didn't seem happy. I just added 40% to my map and flashed the pcv and it's run great since. whole thign took like 20 mins :)

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