/ Register

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Help BDST28 throttle butterflys

Discussion in 'Tech Tips' started by soames, Dec 8, 2014.

Page 1 of 2
  1. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK hear is the question do the throttle butterfly's sit tight in the Ventura or should there be a slight gap
    I'm asking because on my spares carbs two of the butterfly's sit nicely ie not light when held up to light source the last two I can seen they don't sit tight , I am guessing that carb sync will be troublesum or am I missing some easy answer
     
    soames, Dec 8, 2014
    #1
  2. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    Assuming that your throttle stops are wound out to the point that they are letting the throttle close fully.
    I can think of three possibilities.
    1/ The butterfly/throat may be worn.
    2/ The butterfly may be bent.
    3/ The butterflies are incorrectly seated on the shaft. This can occur because the screw holes in the butterflies are larger than the screws. This enables you to manoeuvre the butterfly into the optimum position before tightening the screws. I mention that procedure here http://www.litetek.co/Guide_MikuniBDST_Rebuild.html.
     
    • Like Like x 1
    maelstrom, Dec 8, 2014
    #2
  3. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    The carbs are apart for sonic cleaning and only noticed the gap when held up to the light for checking so I'm am guessing there bent,worn. as the two that have gaps are of spares engine that had bent conrods same cylinders
    trip to the engineers then as I don't fancy wrecking the heads on the screws that hold them in after I spent 7 hours yesterday getting the pilot jets out the jet housing
    Or would you say a tiny gap in the throttle butterfly's on all the four carbs once rebuilt would chase a problem ( mixture screw would compensate I guess )
     
    soames, Dec 8, 2014
    #3
  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    The standard screws are brass and are staked. They can come out quite easily, and if not, it is best to use a dremel or similar to grind the protruding piece of screw thread. I suspect that owners trying to use Phillips screwdrivers would be a big part of the problem. I cannot give you a definite answer regarding what is going to happen if you leave as is.
    cheers
    Blair
     
    • Like Like x 1
    maelstrom, Dec 8, 2014
    #4
  5. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    Thanks Blair I will be leaving as is for now until I can get the throttle plates out and check there not bent as you say the holes for the screws are bigger so could be misaligned
     
    soames, Dec 8, 2014
    #5
  6. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK progress on this spoke too ex Yamaha tech seem its OK and I've now put new main jets (8mm ) heads and new pilot jets in put them together n bench snyc'd with fuse wire trick will get photos up when I can and test them on the bike when this frost does one
     
    soames, Dec 14, 2014
    #6
  7. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK so I swapped carbs over on the bike hoping the throttle valve plates would not make any difference first off when I pulled the set on the bike off cylinder four inlets above the valves were half full of fuel wtf good start aye
    I know it was fuel cause I dipped a cuetip in walked out the garage lighter on yes fire so not a cracked head
    Put the spare carbs on but left the airbox off switched to run sucked cokecan full of fuel straight up hmmmm
    Fired right up but 6tho idle backed the idle screw off all the way and then some still 6tho idle
    Now from what I know about carbs / fuel air ratios if the throttle plate is open at idle it does one of two things
    Stalls because not enough fuel too air or over revs
    So I am now stumped again
    As the carbs that wear on the bike are not 3ln1 ( have no idea wot they are ) look pre 88 from the slide shape
    I will try and get photos up when my lappy decides to work
    I'm hoping its float levels are wrong but knowing my luck I doubt it
    So if I have to strip the throttle plates out can someone confirm the screws that hold them are
    M3 5mm countersunk machine screws
     
    soames, Dec 15, 2014
    #7
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    Yes, M3 x 5 oval head countersunk machine screws. The ones I include in my kits are JIS stainless steel. You will probably only be able to buy Phillips if you buy aftermarket and you will not be able to put much torque into them.
    Have a poke around on my web site and read some of the assembly guides.
    The float bowl gaskets can be a good clue as to what those carbs you refer to are.
    The early 2KR models use these gaskets.

    [​IMG]
     
    maelstrom, Dec 15, 2014
    #8
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    You can buy the screws from Suzuki 13604-44080. But it would be a lot cheaper to buy a B Kit from me rather than do that because you get all of the parts you need.
     
    maelstrom, Dec 15, 2014
    #9
  10. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK they are Defo not 2kr carbs but I suspect they might be 3ln 6 or from a totally different model i will have to strip and clean the set that are idling correct in the week and find out wot there off and shelf the 3ln1 set till I have more time
     
    soames, Dec 15, 2014
    #10
  11. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    Yes Blair I had a set a off you for the spare set last month but I didn't know about the throttle plates then so maybe I will have to work out what carbs I have then order all in one go
     
    soames, Dec 15, 2014
    #11
  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    3LN6 carbs are the same except they also use the large square o-rings in the slide housing.
    [​IMG]
     
    maelstrom, Dec 15, 2014
    #12
  13. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    Cheers they seem to be 3ln 6 or diversion carbs from what I can see so far so looks like the slider housing has a seal like your PIC will get them stripped down
    One thing I don't get is the inlet port being full of fuel after the bike was standing for a week
    as for the spare carb throttle plates have sourced m3 8mm countersunk screws will have to check that once I get to the bottom of first set
    If it turns out that I have a 3ln 6 carbs I take it they were improved I might just use them I wonder if that would affect the redline as I know the 18 tho redline was reduced to 15 around 1992
     
    soames, Dec 15, 2014
    #13
  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    The 3LN6 & 7 have Zeal cams and a few other Zeal bits but actually the carbs are unique.
    The Zeal uses 26mm carbs but I am not sure if the 6 & 7 use 26 or 28. Also the square seal is different, being 3YX-1416A-00 for the former and 3LN-14561-00 for the latter. If you give me the size of the square ring you have I can tell you which one it is. I am actually working to complete the 6&7 kits now as that square seal is very hard to find. But with the help of @GreyImport we got hold of one.
    As for the flooding it will be down to the float valve, o-ring or level.

    Might be useful
    http://www.litetek.co/Guide_FZR250Parts.html

    Edit: Found some specs for the 3LN7 and it lists them as having 28mm carbs.
     
    maelstrom, Dec 15, 2014
    #14
  15. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK will be taking some photos today the slide housing does have a square seal at the end and the jet housing has the same seal as the seal you list as diversion / secca11 so I'm getting some were but the carb id isn't there on the carb body so hopefully with the photos later we can ID them also the jet body housing is similar to greys my fizzer post with a slight difference cheers Blair
     
    soames, Dec 15, 2014
    #15
  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    For a start just measure the throat diameter on the engine side. Twenty-six mm will be Zeal and 28 for the others.
     
    maelstrom, Dec 15, 2014
    #16
  17. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    Throat size is 28mm
    Square seal is 30mm * 36mm oblong 1mm thick od
    Inside the float chamber itself there's 2r-1 cast mark
     
    Last edited: Dec 15, 2014
    soames, Dec 15, 2014
    #17
  18. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,108
    Likes Received:
    3,477
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    Ok they are not Zeal carbs. Must be 3LN6 or 7.
    A bit of a rare species.
     
    maelstrom, Dec 15, 2014
    #18
  19. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    OK took the end carb off and can read 3ln 20 then some numbers are unreadable I have seen a PDF file relating to these but its empty so at least they are 3ln carbs
     
    soames, Dec 16, 2014
    #19
  20. soames

    soames Well-Known Member

    Messages:
    60
    Likes Received:
    33
    Trophy Points:
    213
    Joined:
    Nov 23, 2014
    Gender:
    Male
    Occupation:
    problem finder
    Location:
    milton keynes uk
    My Bike:
    fzr250 3ln1
    ok so this is the carb split down [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
    soames, Dec 16, 2014
    #20
Page 1 of 2

Share This Page