Yamaha YZF R125 Forum and Owners Club: Friendly bike community for all. Hose Going From Airbox To Water Pump | R125 Forum
Change
  1. BOTM Winner
    Congratulations grayej! You are the winner of November's BOTM competition!

    Please visit the BOTM section to see more entries, or to enter this month.

    Click here to enter!

Hose Going From Airbox To Water Pump

Discussion in 'Technical / Mechanical Discussion' started by NorthCust, Apr 30, 2020.

  1. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    so I'm wanting to test runnign a pod filter instead of the airbox to prove or disprove a theory, and havign jsut swapped to a bigger injector I had a good poke around the area and it looks like I can temporarily delete the whole airbox assembly without any major issues.

    But there's one hose which seems to go to the coolant pump.. does anyone know what it's for?

    Obvoously if that hose provides negative pressure or does somethign re movign cooland or [insert thing I don't know] then I wouldn't want to run without it but if it's just an overflow I can reroute it..any ideas?
  2. R125Forum.com Advertisement

  3. misiozol

    misiozol Member

    It's breather pipe, one BIG problem I see is that engine will intake hot air thus lowering performance ;)
  4. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    >> It's breather pipe,

    aha ok that's good to know. So I should be able to affix it somewhere to let it continue to breathe and we should be ok..

    >> one BIG problem I see is that engine will intake hot air thus lowering performance

    well for the purposes of testing I could run it without the side triangles, maybe some ducting too if needed. It's more that I want to get a feel for how it behaves without the airbox. Bigger throttle body is on my todo list too and that would probably not fit on the airbox anymore so this is also prior research to some extent.


    Side note:
    Funnily enough I was just thinking about what you said on the other thread about timing chain stretch. Given the way I damaged my last cylinder (massive over-rev from changing down hard instead of up) perhaps it's stretched somewhat. I'd wondered at the time whether the chain would have stretched but didn't clock that it could affect valve timing, plus at the time my focus was "bike running at all", rather than "optimal power band".

    I wonder if what I'm seeing with the very perky low/mid but lacklustre top end could be (partially?) down to timing chain stretch, which has meant the valve timing is now slightly off one way or the other....so perhaps it IS coming on power as it should and all is well, just the power-band has moved bc of force majeure (on the chain).

    I know according to the service manual you're supposed to change all parts for the timing chain (so cam gear, chain and bottom shaft it goes on) but I wonder if I could put a fresh chain on and a vernier adjuster on the cam. The new chain should correct any valve timing probs from stretch, and the vernier would let me push the power band around to where I want it. I don't see me getting a new main/bottom shaft realistically so whilst not ideal it might have to do.

    I'll probably put a longer duration cam in first as my hope that'll wake the top end up a bit, but if I'm wrong and the cam doesn't extend the powerband, just makes more power in the current powerband, maybe ththen the vernier pulley would let me push it back up to 8-10k

    Thoughts?

    Only thing I'm not sure about is the implications of splitting the bottom end.. - could I perhaps just change the cam gear for a vernier one and leave the chain or is that too sketchy and likely to unevenly wear the timing chain or cause a failure or sthing.
  5. misiozol

    misiozol Member

    Whathever you try to do I have done in mine :D , so changing chain only is bad idea it's just pointless due to wear and tear you need to replace with set, as sprockets wear down as well .About all else would check fuel pressure and injector, service manual is kind of brick as it does not say what should be nominal flow @ what pressure , I do have bigger TB and runs i think same as b4, keep in mind that manifold works like venturi . About air box its not worth your effort, better to make mod for supply forced air induction but thats reqire custom ecu as it needs to be running rich. So in conclussion BUY CUSTOM ECU it will cost you ~150e all in and you have absolute freedom you can use all sensors/injector/F pump etc and have wide band lambda, custom maps etc.
  6. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    >> you need to replace with set, as sprockets wear down as well

    ok but the bottom sprocket is on the shaft isn't it and new shaft says unavailable on msp (and it's £400+ lol)..

    I want to put an adjustable sprocket on the top anyway so top sprocket and chain might have to do.

    out of interest on your custom ecu does that allow timing control too? I was planning to go forced induction on the other motor and normally you'd need to pull some timing out iirc. PCV doesn't let me do that.
  7. misiozol

    misiozol Member

    Yes it does, full ignition map from hayabusa is in mine :D plus dual injection map , have microsquirt ;)
    NorthCust likes this.
  8. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    hmm well my plan was to get the 2nd motor up and running on the standard ecu initially so I know it works and then figure out what to do. The microsquirt seems about the same cost as a PCFC which was another option, but if it gives timing adjustment then it might be the better option.

    I know on the megasquirts you have to add a timing gear potentially (normally weld a toothed cear onto a crank pully or similar) - did you have to do any customising like that to get it running or was it more making the loom/wiring and figuring out the software/maps side?
  9. misiozol

    misiozol Member

    TBH I would NOT recomend now microsquirt as it's double overkill (if one would be not enaugh ;) ) , something like rabbit project or something simple so it cost you not more than ~150e , it was cut and solder plus maps rather simple .

Share This Page