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Help Wait, what? It's too RICH? - ZXR250

Discussion in 'Kawasaki 250cc In-line 4's' started by DamnitLaverty, Apr 9, 2017.

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  1. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    So now I'm mega confused. I threw the ZXR on the dyno this morning- knowing it wasnt making redline, I expected it to be lean. Instead it was just going PIG rich! Rich enough it can't get any RPMs.

    The carbs are rebuilt to stock spec. Float height is in spec. Fresh litetek gasket kit installed. Stock air box. Stock muffler. Fresh air filter. Idles great. Runs great. Gets 38 miles per gallon (15km/l) tho lol and only 20hp (so what, 15kw?)

    What'm I missing? The cheapskate in me says **** tuning it- just take the airbox lid off or install pod filters... but I should fix it properly. I am running outta ideas tho!
     

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    DamnitLaverty, Apr 9, 2017
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  2. Johnny

    Johnny Well-Known Member Premium Member

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    Worn out needle valve needles and/or seats maybe?
     
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    Johnny, Apr 9, 2017
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  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Yeah worn Needle's and emulsion tube's would be my guess.
     
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    my67xr, Apr 9, 2017
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  4. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    Only 32k km on the bike- I'd hope they're not worn. I'll check for specs in the manual I guess and measure.
     
    DamnitLaverty, Apr 9, 2017
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  5. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    GreyImport, Apr 9, 2017
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  6. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    You've set the float height, but have you measured the fuel level? If the float height is fine but there's way too much fuel in the bowls, you need new needles and seats.

    At work I have used autosol metal polish on the end of a cotton tip earbud to polish float needle seats
     
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    Linkin, Apr 9, 2017
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  7. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Also you can modify the slides by drilling an extra 1.5-2mm hole next to the one that the jet needle goes through. Supposed to increase throttle response down low.
     
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    Linkin, Apr 9, 2017
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  8. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    Are all the Needle Springs working properly? If they get stuck or aren't working properly they can cause odd issues.

    Needle Spring.jpg
     
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    Frankster, Apr 9, 2017
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  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Check all of the choke plungers. The float heights were set with the tip of the needle just touching without compressing the spring? Are the main jets standard size? Owners fit bigger jets because they think it will make more power.
    There also exists the remote possibility that someone has drilled out the main jets.
    The chances of being able to get it run with pod filters are slim to none.
     
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    maelstrom, Apr 9, 2017
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  10. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    Yep, confirmed good.

    Yep set properly and yep, stock size jets! dunno about drilling, but nothing else on the bike leads me to believe fuckery is afoot.
     
    DamnitLaverty, Apr 9, 2017
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  11. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    But have u replaced the needles? ..... the rubber tip is probably hard as a rock .... something that really cant be seen or felt .... and if so its probably not shutting off the fuel 100%
     
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    GreyImport, Apr 9, 2017
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  12. kiffsta

    kiffsta Senior Member

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    do a plug chop, let see whats going on
     
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    kiffsta, Apr 9, 2017
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  13. sharky

    sharky Well-Known Member

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    Do you have the stock zxr needles(left needle) or the adjustable needles & clips. The float needles could be on the pin back to front which causes seating issues, the float needle spring as @Frankster mentioned also. What are the pilot screws set at?

    20170409_112107.jpg
     
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    sharky, Apr 9, 2017
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  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    If the bike is breaking down at high rpm then it cannot burn the fuel being drawn in and it will show excessively rich on the dyno. The operator should know this of course.
     
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    maelstrom, Apr 9, 2017
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  15. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Also, have you checked for air leaks? Do you have the 6k-8k rpm flat spot? I'm assuming you replaced the fuel and air o-rings bewteen each carb body when you had them apart, yes?
     
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    Linkin, Apr 9, 2017
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  16. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    With only 20k miles on it, i didn't replace them.

    Will do in a bit. The Ducati took a hit yesterday and right now the only functional bike I have is the ZXR, so I kinda don't wanna disable it.

    Nope, I haven't. I presumed an air leak would make me run lean. No 6-8k flat spot. Yes, i replaced all the Fuel and air o-rings.
     
    DamnitLaverty, Apr 10, 2017
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  17. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    So yeah, yesterday was an adventure! Dyno, then went home to grab the Ducati. Hit a pothole hard enough to break all 4 fender mounts and run over my own front end, bent a fork and pooched a rotor.

    Didn't wanna take the ZXR down, but i wanted to try an experiment today. I removed the airbox lid to try and get more air to the excessive fuel.

    HOLY CRAP! it sounds awesome, it runs awesome. FINALLY ALL THE WAY TO 19K!

    Obviously the problem isn't fixed, but it's mitigated for the moment until I can settle the Ducati with the city's insurance. I haven't solved WHY it was rich, but at least i can use that fuel now. :)
     
    DamnitLaverty, Apr 10, 2017
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  18. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    I would think the age of the rubber tips would affect them more than anything

    Did u have just have the lid off or was the filter out also?

    Bummer about the Ducati ... must have been some pothole !
     
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    GreyImport, Apr 10, 2017
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  19. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    Lid off- carbs exposed. the box still has the filter in it, but it's out of the way from actually DOING anything.

    Yeah, the pothole was terrible, it was damn near a hole to China.
     
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    DamnitLaverty, Apr 10, 2017
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  20. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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