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Help FZR250 3LN3 carb problem.

Discussion in 'Yamaha 250cc In-Line 4's' started by Gert, Jun 15, 2016.

  1. Gert

    Gert Active Member Premium Member

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    Problem with my FZR:

    First, the carbs were dirty due to the wintertime and bad fuel with.
    So, cleaned the carbs. Nothing special. Does happen often in the spring. Most of the years there is one bike in the spring with faulty carbs.
    After that I balanced the carbs. Build the bike together and ready.
    Next time I wanted to ride, the cilinder number 2 was flooded. Crank full with fuel too.
    So, swapped oil and filters and cleaned the carburators again.
    Since then, problems.
    I can start the engine without choke ( too rich?)
    After a few seconds the engine is flooding and the bike stalls due to too much fuel.
    It is possible to keep the engine running, but only with 100% throttle and then the engine makes about 1.500 rpm.

    Changed fuel level, now the engine is running a little time longer, but if I try an testrun, after 100 meters the engine stalls.
    If I shut the petcock, the engine does run good untill te bowls are empty.
    If I disconnect the fuelpump, the fuel level is not high enough to feed the engine under load. And with fuelpump, the engine floods.

    Here are some pics I made checking fuel level on the bike.
    Level without fuelpump:
    http://www.celica.dds.nl/plaatjes/brommer/fzr/carbs/3LNcarb04zp.jpg
    Level with pump and running engine:
    http://www.celica.dds.nl/plaatjes/brommer/fzr/carbs/3LNcarb06mplopend.jpg

    So, I am afraid there is something wrong with the floats or float level pin. So I ordered float needle valves at Yamaha.

    Searched the internet, found Blair at Litetek.
    Ordered the gasketkit and asked for help.

    Blair advised me to join 2fiftycc. I did.

    He advised me to probably change the emulsionpipes and the needles too.
    Found them at motorcyclywarehouse, but that is an complete rebuild kit. Is there a way to buy just the two pieces somewhere?

    Yamaha can deliver them, I know, but only at massive prices.

    Ideas anyone?
     
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  2. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Without a doubt the problem is the needle and emulsion tube. I could not find just the needle and tube anywhere on the internet, so in the end, I bought the Keyster kits from motorcyclespareswarehouse and Blair's litetek kit. It was worth the cost to get the bike running properly.

    They keyster kits are good because they contain brand new jets in addition to needles and tubes - they make a big difference.
     
  3. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Its a bad design with the early needles and tubes ..... they lie on an angle and wear .... later carbys had a spring system to keep the needle centred in the tube at all RPMs

    Not always visible but theres usually wear marks on the needles and the opening in the needle jet will not be round.

    needle 1-3-5.jpg CarbNeedleAssembly 6-7.jpg
     
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  4. Gert

    Gert Active Member Premium Member

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    I did ask really nice if they sell the needle and pipe seperately, but they just do not answer... :(
     
  5. Gert

    Gert Active Member Premium Member

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    Since they are not responding, Ik placed an order today. They probably recieve these kits as one from China or so? I dunno. We will see.

    Let's wait how soon the package arrives.
     
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    They are Japanese Keyster kits. They have 2 separate version for the 2 inside and 2 outside pairs of carbs.
     
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  7. Joker

    Joker If you want me find Club250 on facebook. Premium Member Contributing Member

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    Ok so did it run OK before you let it sit for winter (I assume that is what happened?) Did you change anything over the winter until the time you went to clean the carbies? What did you clean the carbies with?

    It sounds to me like you're letting too much fuel into the engine. I'm trying to be logical about the thought process:

    (1) Needles & emulsion tubes - Gradual decline over time probably...
    (2) Pilot screws - If you haven't touched this and it ran well before then shouldn't be this.
    (3) Jets & sizes - As per (2)
    (4) Fuel float levels - you adjusted this and saw an improvement. Interesting.
    (5) Float seals & needle recess...

    I'd be looking in the area of (4) and (5). O rings get eaten alive by carby cleaner so just something to consider. Rather than type it up myself:

    http://www.cyclepedia.com/manuals/online/free/fuel-system/float-valve/
     
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  8. Gert

    Gert Active Member Premium Member

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    Got mail today from Motorcyclespares that the kit comes only as an complete set. Okay, I was afraid so, I already ordered the complete kit some days ago.

    @joker. No, the bike ran already fine this year. After three tanks of gas, the problem suddenly showed up.
    I cleaned carbs more often, that is nothing new. It is new that the engine does not want to run anymore.

    Just got an message from the Yamaha dealer that the float needle valves landed.
    Soon I will recieve the Litetek kit and after that the Keyster ones.
    I am very curious :)
     
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  9. Gert

    Gert Active Member Premium Member

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    Wow, Blairs package has just arrived! You beat the rest. Points up :drinks:
     
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    and you paid the right price for shipping too :)
     
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  11. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Subscribed...

    Interesting, so can I assume from this that the 3ln3 onwards do not suffer from the chugging problem, mines been sitting in the garage for a very long time because I never did solve that one issue


    peace out

    Glenn
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Hi Ruckus,
    Where have you been? Yes, it was the needles and emulsion tubes. You will have to dig the old girl out of the shed.
    cheers
    Blair
     
  13. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    My Bike:
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    Short story - blew the output shaft of the Fizzer, couldn't get it back on the road in time to keep commuting.

    Bought an '05 GSX-R750 with a Akraprovic Full Titanium header system and Carbon Shorty end can, man that girl kicked, after a few months I had rubber, suspension and steering sorted, only ever managed to test it out to 220 KM/hr - redline 3rd gear on a six seed box- IT HAD LEGS and it handled beautifully, perfectly neutral steering and sliced through traffic. Lightest Gixxer 750 they've made and power to burn!

    Rode it 7 days a week rain, hail and shine till I had a guy turn right and pull across 2 stopped lanes, right on dusk, wet roads, into the bus lane where I was travelling, put her down, missed the car by centimetres, the bike peeled his bumper bar off and I ended up slamming up the gutter.

    Luckily I had cat like reflexes otherwise it would have been the full double somersault over the bonnet, the wet road actually helped because the front locked when I clamped and twisted and just slid - I hit the road hard.

    Sore shoulder for 3 months and had a huge haematoma on my hip for 4 months, but nothing broken or permanent.

    The Insurance company wrote it off because there was supposedly a mark on the frame...BUGGERS!

    Now I am in a "tin top" and filled with the sadness which afflicts all commuters stuck in traffic and need some bike time.
     
  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Oh bad news, but like you said you weren't hurt too bad. The Fizzer output shaft bearing collapsed? Maybe you could pick up another Fizzer engine without spending too much.
     
  15. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    the fizzers output shaft is kaput, the sprocket that came with the bike, unbeknown to me was a loose fit on the shaft, and it worked the nut loose which destroyed the thread. I spot welded the nut back on knowing that the shaft needed to be replaced however the sprocket rocked back and forth tearing through the splines - I did manage to get an extra four months out of the shaft.

    I believe the 3ln3 forwards have more meat on the splines for the sprocket which are longer, I'd love to find a parted out 3ln3 engine for the shaft as I don't need the whole engine, specifically because I simply don't have the space to store any spare parts at the moment

    I am also going to have to do something about that blasted front end, got an R6 rear shock which made a heap of difference, that font end is still to be dealt with

    peace out

    Glenn
     
  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  17. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    guys you rock because I have lost count of the number of times I had those cursed carbs out on the bench, over and over and over again...

    And it was the needles and emulsion tubes all along, not the blasted float level

    On a related note, is it possible to retrofit the 3ln3,5,6,7 spring loaded needle retention system to the 3ln1 carbs or do I need to search out a full set of later carbs. I'e never had any other than the 3ln1 carbs to actually look at so I don't know the differences in any other parts
     
  18. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Guys I also want to add it is good to be back because you're a really great bunch with a wonderful sense of community
    The internet is so seldom friendly and helpful these days

    I applaud all of you

    peace out

    Glenn
     
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  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    @GreyImport & @Linkin have pics and details on those differences and would be able to answer that question.
     
  20. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    And I agree, this forum has a good sense of community.
     
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