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Help Suzuki GSXR250 revving issues

Discussion in 'Suzuki 250cc In-line 4's' started by Simon, Sep 9, 2018.

  1. Wozza

    Wozza Active Member

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    You need to work out if electrical or fuel...close the plug gap a tad and see if that helps...get some maf cleaner or similar spray..you spray it on to cool electrical units like cdi? coils ect...grab some start you bastard and spray that into the carbs as it starts to run rough see if it picks up (just be bloody careful as it is a flammable gas :) ) run some injector cleaner in the aux fuel bottle and finally get some fresh fuel from an independent source...some one may have thrown sugar in the tank ;)

    Ps is your bike cdi or tdi?
     
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    Last edited: Sep 10, 2018
  2. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    CDI has not been seen since the olden days of Kawasaki two stroke triples and the like, to the best of my knowledge.
    The auxillary fuel tank that you are using has a vent?
     
  3. Wozza

    Wozza Active Member

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    honda used cdi up to the late 90's :)..or is the 90's now considered olden days ..it was like yesterday to me :D
     
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  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    My MC22 is 1990 or so, it uses TCI. Which models used CDI?
     
  5. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    My '99 R6 uses CDI, but it also has a throttle position sensor on the carbs... they use it for 3D ignition advance
     
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  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    This is a DC CDI. There is no 12v + connection to the coil. These things are nasty and give a serious shock, wear gloves.
    The early Kawasakis were AC and the ignition was completely independent of the battery.
    IgnitionDC_CDI.JPG
     
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  7. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    OK I just watched your video, and it is the exact same symptoms I experienced on an FZR250 with worn out needles and emulsion tubes. This leads to massive oversupply of fuel, horrible fuel economy and crappy low end power. @GreyImport also looks like the same 'dead throttle' symptom that your FZR has.

    The GSXR250's use the same Mikuni BDST carbs as the FZR250's.

    I bet my bottom dollar that your issue lies with the needles and emulsion tubes.

    As a test, use an aux fuel tank with a fuel tap inline. When the issue occurs, keep the throttle wide open and shut off the fuel. After a while it will clear and run fine until the bowls are empty.

    I became very familiar with the above technique to avoid stalling and holding up traffic.
     
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  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  9. Wozza

    Wozza Active Member

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    most of honda's high reving singles used cdi...XR XL GB....
    Reason I asked is the OP posted he check cdi unit...if its actually a cdi unit then the broken magnets might be causing issues with it
     
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  10. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I know the bigger GSXR's from the late 90's to around 2005 used a cdi, that's why you can't use their Pencil coil's on our TCI ignition bike's, the primary and secondary Ohm'/s in their coil's are a lot lower
    And yeah i was only telling Frankster the other day about the 200+ Volt's going from the CDI to the ignition coil's on some bike's.


    That flywheel with the broken magnet's look's like it's been taken off without using the proper tool to do it at some stage
     
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  11. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Wow guys.. I'm working today so will be a bit quiet..but a massive THANKS to all.. that's a comprehensive list to go at.. and lots of pointers.. didn't consider the needles and emulsion tube at all..will try each and every suggestion.. can't thank you guys enough
    Cheers, si
     
  12. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Yep it's got a vent.. and it's clear. When I say I've checked the cdi I replaced it from my other bike which I know to be good.. and when I say cdi Im referring to transistorised ignition unit located on the LHS near the battery.. Cheers for the help buddy.. me likes that mc22 you've rescued!!!
     
  13. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    I'm going about locating another flywheel.. unsure if it's the actual problem but there's no way of rescuing the old one.. be a lot happier when it's traced back to either ignition or fuel.. thanks for all your help and keep the ideas coming boss, cheers si
     
  14. Simon

    Simon Well-Known Member Premium Member Contributing Member

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  15. ShaneP

    ShaneP Well-Known Member Premium Member Contributing Member

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    Aren't FCR flat-slide carbies? Is that what you have one the other bike? I've seen them for sale, at about $2000!
     
  16. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    In the absence of having an inline fuel tap to hand, improvise using a c clamp attached to the fuel line when it starts to happen to cut off fuel supply and see if the engine corrects itself until the bowls run dry...will do boss
     
  17. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Quite a thread that one, but its shockingly similar to what I'm looking at Blair. I've priced up new floats, starter jets, main jets, pilot jets, emulsion tubes and needles (all x4) and its working out as £630 plus duty which will take it to £800 or so to make the carbs 'as new' with genuine oem Suzuki parts. Mega expensive when I can get a full set of FCR's from the States at £590 built to order, with duty around £750 all in..if I can narrow it down further to fuel then will probably go with this option...thoughts? cheers matey
     
  18. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    There about £600 (GBP) buddy, imported from the US..built to order using FCR 28carbs (used/rebuilt)..plus import duty..all the guy needs is the spacing between the centre line of the existing carbs as he machines them to fit less setting them up (jetting). I've had a set a while back which are still going strong now..but cost £300 to set up properly on the dyno. Webike do a set at 1100£ for the bandit 250, again FCR 28's which should bolt on and require minimal adjustment (new
    https://japan.webike.net/products/1228208.html)..wowcha..expensive I know!!! FB_IMG_1536618516602.jpg

    ..cost of rebuilding the BDST 32's is around £800 with oem parts (I'm on webike now getting a proper quotation) so im thinking go all in and fix it..if that's the problem! I was thinking to take the carbs off the other bike (known good) but its running higher compression, +1mm slipper pistons and different cams plus a flowed head - the bank will likely be massively overjetted..so came up with a compromise..so I can work out whats going on..got a spare bank of carbs..currently measuring up what's good what's not..so I can order just what's needed and keep the cost down
     
  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    £800 with oem parts :confused: I think your FCR option sounds better. Speaking of FCR's how much performance difference did they make Simon?
     
  20. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Jets don't wear out. You can just buy a small ultrasonic cleaner and clean them. The needles, emulsion tubes, and float needles eventually need replacing, but inspect them first. Of course diaphragms and all the rubber parts. Remove those pilot merge bungs too and replace those o-rings. If you are going all out you may as well replace the throttle shaft seals too. Not so difficult on Mikunis.
    'B' kit at the bottom https://litetek.co/Carb_Kit_Suzuki_GSXR250RK.html
    and guide is here https://litetek.co/Guide_MikuniBDST_Rebuild.html
    I can't find any 28mm FCRs anywhere for that low price, source?
     

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