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Project First bike, the FZR250 3LN

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

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  2. I_b_pirate

    I_b_pirate Well-Known Member

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    Got the new bushings in finally so ill be reassembling it this weekend. This is the old bushing compared to the new one. Really needed them done

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  3. I_b_pirate

    I_b_pirate Well-Known Member

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    So new steering bearings and forks fully rebuilt and it feels like it's trying to lean right and feels kind of stiff to ride. I have done the steering up too tight or is it in the front end?

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  4. jmw76

    jmw76 Well-Known Member

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    If the steering is too tight they tend to feel a little strange in a straight line. It is difficult to hold your line and you feel like you have to make conscious steering corrections all the time. Nip it up so that there is just some mild resistance to turning (when the wheel is lifted off the ground) but no lateral movement in the bearings.
     
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  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    @GreyImport also posted a link to a Dave Moss video which give a detailed process for putting the front end back together to ensure that there's no twist through the forks and triple clamp
     
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  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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  8. I_b_pirate

    I_b_pirate Well-Known Member

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    And just like that it's fixed the swaying problem. Can now take both hands off and rides straight. Such an easy fix to simply align the forks. Cheers for that link. Now just got to tune in the right fuel (still rides a bit lean) then on to visuals

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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Thanks for reporting back, it adds to the collective wisdom
     
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  10. I_b_pirate

    I_b_pirate Well-Known Member

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    She handles nicely now but this fuel issue has me stumped. I tried adjusting piolet screw but now it's rich on idle but as soon as you give it some throttle it goes lean and loses power, if I ride with the choke on I have power up till about 2 3rds of the throttle till I feel it lose power.

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  11. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    You've basically been through everything, long thread, I did just skim read it quickly
    Catch me up, we'll go through the basics

    Did you manage to locate EXUP cables and get that sorted?

    Airbox and filter?

    CARBS
    Fuel levels worth checking as it's quick and visual - this one basically rules all other carb settings, I know you've been through that part, this is a checklist item though

    All 4 needles on centre clip

    You put Keyster kits through? - I didn't see anywhere that we informed you that the centre and outer main jets are in the incorrect boxes - centre pair get warmer intake = less dense = smaller main jets AND out pair get cooler air = more dense = larger main jets

    Plus the centre pair have the 0.5mm washer beneath the needle

    Carbs bench synced - a 1mm drill bit or piece of soft copper wire will do this

    Are your intake boots all snugged down and free from cracks, I know you were chasing the rubber carb joints to the airbox, inspected the carb -> cylinder head boots closely?
     
  12. I_b_pirate

    I_b_pirate Well-Known Member

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    Yeah exup cables from the 400 fit perfectly and are adjusted properly using a spanner on the valve. It cycles properly when powered on everytime. Got them from Ali express pretty cheap.

    Carbs have new keyster kit and all the jets in the right place, even got new diaphragms as well and used proper balancing gauges to get them balanced but they still were coming up lean.

    The intake interfaces are a bit cracked but nowhere that they will leak, tried to order new ones but they never arrived. They sent another 2 sets after I contacted the seller but still got nothing so I soaked the rubbers in methyl silicate and alchohol and coated them in high temp silicone to stop any potential leaks. Im gonna try get more through a different supplier after I move house. Just trying to think of anything else it could be.

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  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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  14. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Which fuel are you using? I found that these small inline 4's do not like 95 or 98, try a tank of no ethanol 91 and reset everything to standard as far as the carbs go.
     
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  15. I_b_pirate

    I_b_pirate Well-Known Member

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    Ok quick update, while waiting for the interfaces to arrive decided to try set all carbs to standard and rebalance. Went to check the jets to make sure they weren't blocked and found 2 of the carbs had the jets the wrong way around. Switched them around, set the needles to 3rd notch with a 1/2 mm washer to space the inners, set puolet screws to 3 out and put it back together for tune only to find the fuel pump silent. So taken it out and gonna strip it and see if I can fix it tomorrow but fingers crossed the problem is fixed with the jets.

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  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Check the fuel pump relay also - pretty sure that there is one, although I've never had a working one installed
     
  17. I_b_pirate

    I_b_pirate Well-Known Member

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    I put 12v directly to the pump and got nothing. Also noticed a bit of a fuel leak when it wouldn't start a few days ago.

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  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK, so you know, you can run a 3LN without a pump just via gravity feed, BUT I would check the "fuel level/height with the carbs installed" with say 1/2 tank of fuel as a way of determining if there's a difference in fuel height in the carb bowls with and without a pump

    It's easy enough to check
     
  19. I_b_pirate

    I_b_pirate Well-Known Member

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    Im a bit weary of riding it with gravity fuel but checked the balance and all looks fine. Was looking at new pumps and not sure if I should get a cheap $35 one from Ali express or spend a bit more.

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  20. I_b_pirate

    I_b_pirate Well-Known Member

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    New pump in, turned over and it fired straight up. Fixed the throttle problem with the jets too and she runs mint. Might be a little rich so I'll dial back the piolet screws 1/4 and see how that goes but it's not boiling the coolant due to running lean on 2 cylinders. Went for a nice long run and didn't overheat al all and she gets about 180km till I need to switch to reserve. I think I will hit the 200 once I dial back fuel.

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