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Project First bike, the FZR250 3LN

Discussion in 'Your 250cc Projects' started by I_b_pirate, Feb 17, 2020.

  1. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    You only remove those clips if your replacing the leads with new ones .... the connection there should be fine .... and yes those clips are brittle and require perfection to remove and reuse
    Its the plug cap end that gets corroded .... its all in the link Ive already posted above
    The cap just screws off and a few MM is cut off the lead and the cap screws back into the lead ... and u check for any 'green' inside the cap which means corrosion has set in
     
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  2. I_b_pirate

    I_b_pirate Member

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    In side the caps are all shiny brass but the ends at the coils were brown so I gave them a trim.

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  3. I_b_pirate

    I_b_pirate Member

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    Leads are now nicely trimmed and found a solution to my clip problem. One of the leads were so bad I had to cut about 6mm off before I found copper but they all getting good connection now. Bit too late to try start it tonight so will try tomorrow and let you know how it goes.


    [​IMG]

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  4. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK so I just did some reading and now that I've done it, it's obvious - the coils will have a polarity.

    https://www.aa1car.com/library/ignition_coils.htm

    So someone else with a fizzer and the coils accessible and a multimeter can tell you if which is the positive spade connector on the coils, although just looking at the wire colours -v- black wire is a pretty big clue

    The difference is minimal as if it was wired backwards - the voltage to charge the secondary would need to go through the primary first so the spark would be weaker, just how much weaker is unknown.
     
  5. I_b_pirate

    I_b_pirate Member

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    But the black wires each go to different wires on the loom. Both coils have a red/white wore that goes to ignition according to wiring diagrams and one coil has a solid orange wire while the other has a solid grey wire. One black wire goes into the orange while the other goes into the red/white of the other coil.
    Don't know if that's how it's supposed to be but at the moment I've got the positive of both coils going to the red/white (ignition) and negative going to the orange one and the grey one ( ignition box).

    From what I can assume the ignition feeds the coils constant power and the igniter box grounds the coils was on the timing.

    All the cylinders seem to be sparking but I think it's still not getting enough fuel even though the fuel levels in the carbs are fine. Could it be the jets maybe?


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  6. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I'd ignore the loom further down, those two plugs to the coils cannot be connected backwards, IDK if we have a colour schematic of the wiring

    I've often seen wiring colour changes through a loom - it's a pita especially when trying to diagnose shorts or open circuits with hidden or difficult to access plugs where the changes occur.

    Blocked jets, especially the smaller ones related to idle will cause problems and now I've just remembered the idle air jet adjustment, small one from underneath at the front of the float bowl, tighten gently till it stops then come back out about two turn IIRC

    @my67xr can tell you what he's got his tuned to in case the 2 turns is incorrect as I know he's done extensive work getting that and the carb balance sorted @Linkin may be able to assist also

    Is there at least a slit of light through past the butterflies? Last thing may be the idle set too low

    Somewhat surprised it hasn't come to life by now, you've got spark, should have fuel...did you try the start ya bastard?
     
  7. I_b_pirate

    I_b_pirate Member

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    Yeah I've tried start ya bastards and it pops but doesn't fire up. I have the proper screws set at 3 turns so maybe that's too much, I'll try wind them back.

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  8. I_b_pirate

    I_b_pirate Member

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    Could the fact that the valve clearances are slightly too tight be the cause? I know the pilot needs vacuum to pull the fuel through. It's just not getting enough fuel now. All the cylinders are popping but only when I put fuel or syb down it's throats. Yet it's still not enough to fire.
    I've run the battery flat trying so I'll charge it up and have another crack tomorrow, maybe have a bit of a play with those pilot screws to find the right setting.

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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK so those screws are pilot air jets, they meter the air, not the fuel, try 2 turns in, from memory that's about where it's supposed to be, 1 3/4 - 2 - and I'm hoping that someone will step in and correct me on that
     
  10. I_b_pirate

    I_b_pirate Member

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    I thought if they were engine side of the butterfly they were fuel and if they were airbox side they were air, maybe I'll have to wait till I get the rebuild kits and replace the jets.

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  11. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    BDST 28 carb chart.PNG
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Correct. Air screws make very little difference. Fuel screws can be very sensitive and should be tuned to suit the engine. The 'n' turns out should just be considered a guide. https://litetek.co/Guide_FuelScrews.html
     
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  13. I_b_pirate

    I_b_pirate Member

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    Had another thought, is the ignition timing run off the crank, and is it possible that when the head was put back on the crank was set to TDC on the exhaust stroke instead? Cause that would mean it would spark as the inlet opens which is what has been happening.

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  14. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That's what swapping the coils over has accomplished, the coils - the pair of them, fire twice per revolution as there are two ignition events per rotation

    If when you got the bike the positive and negative were wrong (backwards) at the blade connectors on the coils, then there's every chance that they're connected wrong, so try swapping them, but I thought you'd tried that already.

    Only other thing to check, cam cover off, turn it to TDC cylinder 1 firing and check the line with the two dots and the cylinder head mating gasket surface line up AND that the small dot is UP for both cams

    I know you measured the valve clearances to be right on the low side of clearance
    Do you have a compression tester?
     
  15. I_b_pirate

    I_b_pirate Member

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    Yeah I just picked up a compression tester yesterday was gonna be my next job. So there isn't really a firing order like on car engines? It's just 1&4 then 2&3.

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  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Well there is a firing order, which is governed by the cams, however because it's wasted spark, it's not like say a car with a distributor or ECU firing only one individual plug at a time, it fires the plugs in pairs, which was why I suggested switching the coils in case it was firing the wrong pair each time - the popping from the exhaust &/or inlet was a clue

    It's firing order is 1-3-4-2 IIRC, but that's on the cams, it fires 8 plugs, each one twice on a full firing sequence
     
  17. I_b_pirate

    I_b_pirate Member

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    So I went to do pressure tests and one of the plugs snapped off in the head, luckily it wasn't in tight so managed to get it out without taking the head off but now I gotta get new plugs before I can try to start it again. Double checked the timing and it looks like the intake is out a little bit.


    [​IMG][​IMG]

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  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That would be down to chain stretch that amount, I don't think it's out by a full tooth on the cam
     
  19. I_b_pirate

    I_b_pirate Member

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    Na I moved the cam one tooth and it's the same amount the other way so I'll probably be looking at a new chain sometime.

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  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK then that is a lot, especially with 13K KMS on the clock - perhaps not real numbers as you suspected

    Did you manage to get compression numbers on the cylinders?
     

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