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2KR with an EXUP valve??? And what 3LN1/2KR parts interchange?

Discussion in 'Yamaha 250cc In-Line 4's' started by millenium7, Sep 16, 2015.

  1. millenium7

    millenium7 Member

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    Everything i've read suggests that in 1989 there were both the 2kr (non exup) and the 3ln1 models (with exup)
    Mine definitely is a 2kr chassis and plated 1989, single front disk, twin headlights. However it has an EXUP valve in the exhaust. And I just pulled the CDI and it is labelled 3HX-82305-00 which is from the 2KR models

    I have absolutely no history on this bike, no idea if the engine has been swapped, or just the exhaust or what. Were there ever any 2KR's made with an EXUP valve?
    Chances are i'm going to need parts in the future and at the moment i'm not sure what fits what and if I should be ordering 2KR, 3LN1 parts or if it doesn't matter for certain things. I may need things like carby parts, intake manifolds, cables etc in the future. May even need a CDI which I notice has a different part number but same plugs (do they swap?)
     
  2. risky

    risky risky

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    early 2kr,s had no exup but later ones did.
     
  3. Moo

    Moo Plodge Racing!!!

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    Pictures?? knowing if its an early of late 2kr will help.
     
  4. millenium7

    millenium7 Member

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    Only photo I have at the moment
    [​IMG]
     
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  5. Moo

    Moo Plodge Racing!!!

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    my understanding is there is a good few interchangeable parts, non motor and motor.

    Examples that i am aware off: (open to be told i'm wrong)
    3LN bars and top yoke of the tripple to position your bars more aggressively. 3ln front end....forks, wheel and brakes, rear wheel ect.

    Wheel bearings and seals are the same, the engine casings are the same for example the stator cover will fit the 2kr the 3ln and the zeal, head gaskit and majority of engine seals are also the same as they all fall into the 1hx family code.

    unsure of the carbs.
     
  6. millenium7

    millenium7 Member

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    Engine # starts with 1HX. I believe the engines use a different oil filter design, and i'm not sure where the filter is on mine

    The carbs... now I took the airbox off a couple nights ago, more accurately it basically pulled straight off with very little resistance, i'm unsure if the intake boots were even secured on there. And when I went to put it back on I thought how in the flap do you get this stupid thing on? It's by far the most retarded design i've seen as its next to impossible to really know if you've got all 4 on their respective carbs. I took the boots out of the airbox and tried to fit them individually, they are SO tight that I cannot get the damn things on all the way. I can get them on slightly skewed, but not seated (can run my fingernail around in the inside and feel theres a big gap on 1 side, always). I'm a pretty strong guy, and I cannot press them on all the way no matter how hard I try. And when I go to do up the clamp and then try and fit the airbox down on just '1' intake boot I can't do it, because of the lip it has to sit into. Doing it the other way (just pushing the airbox down, with the boots already in the airbox) seems impossible to get a proper seal due to no way to wiggle or stretch the intake boots

    This makes me think that maybe the engine and certain bits have been swapped, including exhaust and carbs but not the airbox, and maybe there's a mismatch in the diameters. I know intake boots can be a little difficult to fit, but this is just insanely stupid
    What I think i'll do is buy some radiator hose large enough to quite easily slip over the carbs and intake boots, cut into 4 short sections that slip over the carb and intakes, then secure them with 8x hose clamps. Or should I just completely piss the airbox off and use 4x pod filters?
     
  7. risky

    risky risky

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    forget pod filters period.oil filter on 2kr is under motor and to access it needs fairings and exhaust OFF. is a paper cartridge while 3ln,s have a srew on canister.carby boots need a few choice words and much patience.
     
  8. Murdo

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

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    And rubber grease! Maybe try softening them with a hot air gun.
     
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  9. millenium7

    millenium7 Member

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    Used rubber grease, no go. I can't physically stretch them over with my hands. Whats the easiest method, fit the boots to the carbs then wiggle the airbox on, or fit them in the airbox then somehow get them on the carbs? I'm still thinking I won't bother i'll just use radiator hose, that way I can get the correct size, mount them to the intake boots, then simply slip them over the carbs and tighten down some new hose clamps, piece of piss
     
  10. Murdo

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

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    With some of my restorations I have had to heat the carb rubbers individually and stretch them over a piece of pipe and let them cool before they will attach to the carbs.
     
  11. millenium7

    millenium7 Member

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    Cool, radiator hose it is then. Hah

    On another topic, I definitely need some new friction plates. Took it for a good ride today and if I race shift into 3rd there's a lot of slippage. Are the plates and springs the same for all the engines?
    And does anyone have the tolerance specs for the springs?
     
  12. millenium7

    millenium7 Member

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    Well, after pulling the carbs apart and comparing them to others listed. It seems mine are somewhat different in design and could very well be from a completely different bike. Here's a couple pics

    [​IMG]
    [​IMG]

    Inlet outer diameter on carbs is 47.5mm, intake boots are about 44.5mm. This may explain why its practically impossible to fit them. No 'mikuni' markings on the bowls. Looks completely different to all the other pics i've seen
    Needle: D4V1 / 3rd clip
    Main: 72.5
    Pilot: 17.5
    Fuel screw???? I can't see them
     
  13. Lynxdragon

    Lynxdragon Well-Known Member

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    air screw is on the top by the diaphragm cover is memory serves me. I made carb to air box rubbers out of silicone hose, I still have more then enough left if your interested. just be sure to cut the hose the same length as the old throats on the rubbers, else makes it impossible to tune.


    Sent from my iPhone using Tapatalk
     
  14. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    That's interesting - looks like 2KR's had the same design as the 3LN6/7 carbs with the spring holding the needle in. I wonder why they did away with it from 3LN1-3LN5 ? Cost saving on a 5c spring?

    A 2KR with EXUP is a 3HX1/2/3 - and that is all they are... a 2KR with EXUP valve and servo motor. Likely that the CDI box is different to 2KR's without EXUP.

    http://www.my-x15.net/FZR_INFO.html
     
  15. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    To compare parts just look at the 2KR and 3LN parts books in the Resources

    2KR carbs are 26s and 3LNs are 28s
     
  16. millenium7

    millenium7 Member

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    This is what I have at the moment [​IMG]

    Its just 51mm silicone hose pulled over the old boots, and extends down to the carbs. Effectively the stock boots are just resting on top of the carbs. The carb diameter is I believe 47.5mm and the (presumably stock) boots are about 44mm. Whoever the heck thought this design in general would be a good idea was probably on some serious drugs. My boots are in good condition and pliable but buggered if I can get them to stretch on the carbs. Maybe if I used a hydraulic press.....

    This probably isn't the best method but it is incredibly easy. The hoses sit down on the carbs with almost no resistance, just plonk it in place then tighten the clamps. I thoroughly sprayed the area with starter fluid and had no change in revs, so they're sealing

    What was your design? I didn't full replace the stock boots because I couldn't think of an easy and effectively way to make it seal the airbox side. Then again i'm not so sure I trust the stock boots either... they have a fair bit of play in the lip that sits into the airbox
     
  17. Lynxdragon

    Lynxdragon Well-Known Member

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    my design used thick walled 3 ply silicone radiator hose, I placed that inside the air box in the same manner the old rubbers do and epoxy that in to make sure it's a sealed fit not just pressure fit. the other end you cut at a 10 degree angle and push over the carbs, and hose clamp in place.

    [​IMG]
    [​IMG]

    it's 48mm ID, my bike was a 1986 engine with a 89 carb and frame, with ex up. and as I said before, I have heaps of that hose left. could possibly get the whole assembly off the new owner since he bought new boots.


    Sent from my iPhone using Tapatalk
     
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  18. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Just to let you know, most radiator hose is EPDM and fuel will dissolve it.
     
  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The float bowl seals are a good indication of the carburettor model. If you visit http://litetek.co/Carb_Kit_Yamaha_FZR250_2KR.html you can see the early model parts and also an image of those early models. Click on it and it will cycle through the various incarnations of models prior to the 3LN series.
    [​IMG]
     
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  20. millenium7

    millenium7 Member

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    It's on the air intake side, not the engine manifold. I'd imagine the pissy amount of fuel that gets shot backwards into the intakes would years to have any noticeable degradation to the hose. Judging by the amount of dirt in the carbs i'd say the stock boots weren't doing anything, very likely popped out on the first bump in the road. Would rather have silicone hose than useless intake boots that suck dirt on a daily basis

    I somewhat suspect the carbs have been swapped at some point because the engine - while not spotless - was at least reasonably clean. The carbs on the other hand were absolutely filthy on the outside. I spent most of my time cleaning the outsides of them it was that bad, cleaning just the inside was pointless when as soon as I removed anything all the grease and dirt would just fall into the passages again

    According to the 2kr manual they look similar if not the same, but different to this link http://2fiftycc.com/index.php?threa...0-3ln-bodywork-frame-engine-carburetors.3469/
    Note the needle configuration looks the same on the 3LN6/7, but everything else is very different
    So I wonder if any of the carbs had a different intake diameter. Maybe mine are from a 86 model or something which had a larger diameter, or maybe my airbox or intake boots were replaced with ones that had a different diameter

    Anyone manage to get measurements of theirs?
     

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