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Project FZR fix up

Discussion in 'Your 250cc Projects' started by Yetiburger, Oct 7, 2017.

  1. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    yeah ive had it running. just took it to the mechanic to sync the carbs. seems to run alright but wont take any throttle until its completely warmed up
     
  2. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    That is mixture screw's still, but as i have found, changing them will require another sync
     
  3. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Mixture screws shouldnt affect carb sync .... a carb sync sets the butterflys to work in unison .... when rebuilding I set everything to factory settings then bench sync with a very fine wire in the butterfly after turning the idle knob so it closes etc while adjusting the sync screws accordingly .... then when its on the bike u tweak the mixture and idle for each carb
     
  4. Joker

    Joker CLUB250 Staff Member Premium Member Ride and Events Crew Contributing Member

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    None of my FZR's have ever liked throttle when cold, but they shouldn't cut out when you "blip" them a bit. If they do, as has been said you want to make the mixture screws a little richer.

    If it runs off the key and maybe even with a bit of choke when cold that seems normal to me so I can't see how the compression numbers would be so low... you'd hardly be able to start it if you were outside the compression limits...
     
  5. Mike Fulcher

    Mike Fulcher Member Premium Member Contributing Member

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    Yes I agree using a penetrating product is your best option, our company uses it for everything, from freeing rusted bolts & nuts, to seized up bearings, corroded & seized up Carb. parts.
    The best product by far we have come across here in NZ is a product named Blaster, a very powerful penetrating catalyst. It is also an awesome penetrating lubricant for Chains, sprockets, an to use when Honing Cylinders & for use as a machining coolant & lube, absolutely magic stuff, & that's not a sales pitch, we have to buy the stuff.
    Check it out on www.BlasterCorp.com
    Cheers
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    EDIT: further discussion here
    https://www.2fiftycc.com/index.php?threads/pb-blaster-penetrant.9918/
     
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    Last edited by a moderator: Apr 3, 2018
  6. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    It certainly does on my bike,
    when you get them close to perfect and have to drop the idle speed they need to be resynced again too

    I synced mine with a bit of wire the first time,
    then when i made a mamometer and compared the 4 carb's they were out a long way, same with the Carbtune sync tool
     
  7. beano

    beano Well-Known Member Premium Member

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    i agree craig, ive found that to be true from my own experiments with the morgan carbtune, adjusting the mixture screws will cause the levels to visibly change on the unit.
     
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  8. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    so make the mixture screws richer by turning them in clockwise? the bike dies if you even look at the throttle until it has warmed up for a good 5 - 10 mins. going to tidy the fairings up and just get on the road for now. might pull the motor down mid winter and have a look.
     
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Richer is turn out (anti-clockwise) not in. The further you turn them in the more you block the fuel flow.
     
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  10. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    ohk i thought it may have been an air bleed. hopefully adjusting them makes a difference.
     
  11. Wozza

    Wozza Active Member Premium Member Contributing Member

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    General rule of the thumb, mixture screw between the slide and motor is fuel related and in is lean out is rich,mixture screw between airbox/filter and slide is air bleed, in is rich out is lean ;)
     
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  12. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    On my 3LN3 carb's i first made sure the bike was at operating temperature, (ride it around a few block's)
    then set all the mixture screw's as lean as they can go, eg to the point where the idle speed start's to drop
    It start's easy from cold with full choke, and take's about 20-30 second's to warm up enough top be able to back the choke off to half, then after another 10-15 seconds i can just about turn it off
    At this point it will rev without hesitation and i can ride off, i turn the choke of completely after going 200m or so
     
  13. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    sometimes its easy to forget the genius available in this forum. ive wound the mixture screws out to about 3 turns. now the bike doesn't die under throttle. it does bog down a bit but doesn't die. should i wind them out a bit more?
     
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  14. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    I have finally welded one fairing up. going to give it a sand and bog it up tomorrow. I have a front fairing coming that's in better shape than mine (still broken). is the heat proofing inside the fairing needed and does anybody know where to get it from? 20180411_170543.jpg
     
  15. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Just try small fractional adjustments now .... like ΒΌ turns
     
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  16. Andych

    Andych Well-Known Member Premium Member Contributing Member

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    Have you added any strengthening to the inside of the Plastic weld? Bunnings have sections of stainless steel mesh (Tradeflame product) as well as ABS filler rod. The stainless mesh you melt into the back and it gives the area a lot of strength.
    Best to also use a filler for Bumpers etc.
    I used this stuff on my Across and it worked really well....
    Filler.jpg
     
  17. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    yeah I've been using ABS rods to add extra plastic to the inside of the welds, but some mesh might be good around the smaller sections of fairing.
     
  18. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Read all of @my67xr 's posts about tuning his carbs. I would say that he has done the most to get his FZ running perfectly. It will alway run completely differently cold to hot and all tuning should be done hot.
     
  19. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    I reckon it sound's like your floats may be too low now that the mixture screw's are out to 3 turn's.
    Maybe try the mixture screw's out another 1/8 of a turn first but if the bog is still there i'd be double checking the float height / fuel level
     
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  20. Yetiburger

    Yetiburger Member Premium Member Contributing Member

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    oh yeah could i possibly get a link?
     

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