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Project FZR250 3HX1 1988 - Almost Done

Discussion in 'Your 250cc Projects' started by Why?, Nov 29, 2022.

  1. Why?

    Why? Active Member Premium Member

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    Well I started work on the other FZR250 as I am waiting on parts for the 2KR to complete.

    I thought this one would be easy but the more I pulled off the more things I found wrong.

    The Bike was purchased from a guy who had started doing it up but due to ill health sold all his bikes.

    The good thing I though was you could actually start it and rev it but that was about it.

    So Far:

    Re routed all the wiring via the correct routes which tidied up behind the front fairing. Fixed a couple of damaged wires. My Only win.

    Pulled the carbies off and made sure all jets were clean and re-assembled carburettors. But bugger me now the fuel pisses out of the carburettor when the fuel pump runs. Not pulling them down again today. Carburettors had been played with before and had not seen to much care as bowls were attached with all manner of screws.

    Yamaha air box and filter were no longer in place, it had 4 small pod filters.

    Front brake master cylinder had been replaced with Chinese one and did not work, clutch lever was also a Chinese piece of crap.

    Exhaust servo works but has no connecting cables.

    Very depressing when I thought this one would be the easy one.
    IMG_8427.JPG
     
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    Last edited: Nov 29, 2022
  2. Why?

    Why? Active Member Premium Member

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    Day 2 pulled the carbies down, checked the needle and seats all working fine and sealing, back on the bike all seemed good, bike running then two minutes later fuel pissing out the overflows bugger CAD04CD8-8B02-4466-AAF6-A7F8B89FCD5D.jpeg 78D396D6-2EC4-4B00-A771-361579FB89B8.jpeg
     
  3. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  4. Why?

    Why? Active Member Premium Member

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    Thanks I'll do that, now I'm looking for a wiring diagram, all working except lights
     
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The pod filters are never going to work. You will need to track down an original airbox.
     
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  6. Why?

    Why? Active Member Premium Member

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    I have organised an original air box.

    What I would like to know is have the jets been changed to suit the pod filters? I ask this because compared with my 2KR which had the same carbies, the jets bores on this bike is larger (bigger holes) so I'm wondering if it will run rich with the standard air box?
     
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  7. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Jets are all marked with sizes

    MikuniEmblem2.jpg

    From a rough translation from the 2KR service manual your main jets look to be 72.5

    BDS26 carb settings.jpg
     
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    Last edited: Dec 1, 2022
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Pod filter people, not to be confused with people who want to live in pods, eat bugs, own nothing and be happy, always fit "big jets" because ummmm ...
     
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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    'cos people misheard at some stage, the actual fact of the matter is that big jets = more carbon and less zoom, somewhere, sometime, somehow that all got screwed up backwards, and well the rest is history
     
  10. Alumascoupe

    Alumascoupe Member Premium Member

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    First off, AWSESOME BIKE !! can only imagine the revs she can do :)
    Ok since hating on the "Pod people" has come up (again LOL) I should probably confess I do have a beard, i do have a tatoo, & am technically in an age group many "hipsters" are, but dammit I refuse to eat avocado toast or be pretentious about everything so please don't think I am one LOL
    . I have installed a pod filter on my TW200 scrambler project....a big giant air box really ruins the "look". I would think a pod filter being less restrictive (if large enough) would more or less necessitate running a bigger jet, due to incressed airflow, no ? Obviously not just willy-nilly chuck a big ole jet in, but methodically done by reading plug until you get a good clean burn.
    Since I see so much hate towards pod filters here I gotta ask, what is the big deal ? Is it a lack of vacuum ? Is it that a lot of newbies (like me LOL) Have no clue & think much like putting a fart can on a honda that it will suddenly be faster when its often the opposite if not tuned accordingly ? Is it that sucking warm air from right behind the engine a step backwards ? Why the automatic hate of pods ??
    If I want to have a clean look of no massive chunky plastic box on an otherwise classic looking bike, aside from a pod filter, what are the options other than a big stock airbox ? What wisdom can you guys share to help me keep a clean look without being a "pod people" ? LOL
     
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  11. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Pod filters with CV carbs doesn't work well because they need a non-turbulent supply of air, ie a still-air-box.

    With pods you may get more air flowing by pure volume, but not better airflow.

    On a slide carby it may be different story
     
  12. Why?

    Why? Active Member Premium Member

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    All the electricals now working, have starting issues (very hard to start when cold), waiting on air box and new spark plugs.

    I have an empty connector which I don't know what is for please see attached. Has red and brown wire. IMG_8460.JPG IMG_8459.JPG
     
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  13. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    That red and brown looks like the connector to the rear brake switch.
     
  14. Why?

    Why? Active Member Premium Member

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    Rear brake switch is connected and working?
     
  15. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    I've seen a few 2KR's with that plug, no idea what it is for. It might be switched power for an accessory. See if it has any voltage when you turn the ingition on.
     
  16. Frankster

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

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    Mate, don't hate on the avocado toast just because some knob made it a trending item. Nothing better than smashed avocado on toast with some cracked pepper and squeeze of lemon juice...yummo.

    As for pod filters; yes most of us on this forum do not approve of them being attached to CV carbs. If you must remove your airbox, I would suggest a velocity stack and maybe a mesh filter at the end. I have run CV carbs with open velocity stacks (on the drag strip) and they worked fine, but drag racing is a wide open throttle situation.

    2KR coming along nicely @Why?

    https://tinyurl.com/59ypc237

    upload_2022-12-3_10-22-10.png
     
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  17. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    We don't hate pod filters. If they worked, we would love them. I have told every twin cylinder "cafe" person that has shown up here wanting to fit pods, to buy some Mikuni VM's and go for it. You can't buy different needles and emulsion tubes for OEM CV carbs which makes trying to get them to run correctly, very difficult, so to put it simply, we just say they don't work with CV carbs.
    https://litetek.co/docs/InSearchOfFreeLunch.pdf

    Could it be done on the 250cc 4? I would say it would be extremely difficult compared to the 1100cc four in the article. The 250cc fours are already so highly strung that they are tempermental as is. If someone has enough time, money and access to a dyno with an experienced operator then it should be possible. Personally I would rather fit 4 slide carbs and try to sort those.
     
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    Last edited: Dec 3, 2022
  18. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    A set of Keihin FCR's at their crazy pricing, at least 1200-1500 USD. Still is a cheaper option than all the dyno time trying to get pods to work on the standard CV carbs.
     
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  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Indeed, the Mikuni engineer in the article stated that the factories spend months sorting air boxes, carburetion and exhaust systems. Let's be real, what chance do we have? Knowing that, my take on these topics is simple. I never believe any claim about increased performance unless it is backed up by proof. For example, this Kiwi's YouTube channel has endless vids on dyno testing all sorts of mods on a Toyota. There must be thousands of hours that he has spent on this, that is proof.
     
    Last edited: Dec 12, 2022
  20. Alumascoupe

    Alumascoupe Member Premium Member

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    Ok so the OP has an airbox coming, & spark plugs too, hopefully that cures the cold start troubles.
    I dont wanna hijack the thread to pod filters so I think I will start a separate thread for pod people & those who hate them ;)
    Why? Were you able to figure out that mystery red/brown connector ? You mention exhaust servo not working, could the connector be for that servo maybe ?
     

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