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running problem

Discussion in 'Yamaha 250cc In-Line 4's' started by dustyjax, May 10, 2011.

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  1. dustyjax

    dustyjax New Member

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    Hi
    I am new to the site and new to motorbikes,
    I have just brought a FZR250 1990 3LN import and the guy I brought it off said that the carbs need cleaning as when you try to ride it it stalles. I put carby cleaner down it cleaned the tank replaced the fuel filter and lines cleaned the tap and everything. But I don't have a fuel pump on the bike does this matter the tanks sits higher than the carbies by the looks of things.
    When its idleing it runs good and can be reved to the full rev count with no problems.
    I tryed to ride it and it goes into first but when I rev it, it stalles and I have some trouble starting it again for abount 10 secs then she starts up good again.
    I have noticed the EXUP valve cables are removed and the servo turns when the ign is turned on, but the valve is wired closed but when I turned it to the open position it wont start.
    Any help or ideas would be great.
    cheers Mike
     
    dustyjax, May 10, 2011
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  2. SnowFox

    SnowFox New Member

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    Welcome to the world of Motorcycles!

    Carby cleaner is good for for inbetween services, by the sounds of it the carbies will have to cleaned by hand.

    Fuel Pump is not needed.

    I thought the EXUP is supposed to be wired open if nothing is attached, Dave or someone else can help you with that though.


    Describe the stalling, is it a sudden stall, or a im gonna die any minute stall?
     
    SnowFox, May 10, 2011
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  3. dustyjax

    dustyjax New Member

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    thanks for the reply Snowfox,
    when I am in first and I let the clutch out and I rev it to change gear it starts to cough and spit than stalls takes about 15 secs of cranking for it to start again sometimes with choke on for it to fire than she idles like nothin happened.
    the exup valve was wired in the closed position when I rode it didn't even think of the valve thing until later.
    where is the open position on the exup valve is it full lock on the other side if it is in middle of that it starts but revs like crap.
    Hope this helps explain a bit.
    cheers Mike
     
    dustyjax, May 11, 2011
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  4. dontz125

    dontz125 Active Member

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    Hi, Dusty - glad you made it over here!

    Did you clean the inlet screen inside the tank?

    Have you actually stripped the carbs and cleaned the jets? (There are several how-to threads - my personal comments are: do ONE at a time so you don't mix & match, and DO NOT use any sort of wire to poke gunge out of jet bores. Use fishing line, so it doesn't carve the precision-machined aperture.)

    Have you pulled the airbox and watched the slides hop up and down while you blip the throttle at idle?

    Have you pulled the fuel line off the carbs to see what sort of fuel flow you get? It should be a gush, not a trickle or drool.
     
    dontz125, May 11, 2011
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  5. dustyjax

    dustyjax New Member

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    Hi Dontz125,
    No haven't pulled carbies apart yet was the last thing I wanted to do until I was 98% sure it had to be done.
    The slides move when I give it a rev and cleaned the screen in the tank.
    Full gushes out when I disconnect the fuel line to the carbies.
    thanks for your help.
    Mike
     
    dustyjax, May 11, 2011
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  6. dontz125

    dontz125 Active Member

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    Ok, sounds like you really are going to have to pull them. Not to worry - it really isn't that hard.

    What you're describing - starting and idling well enough, but dying almost immediately under load - sounds like fuel starvation. You've established that you have good fuel flow TO the carb, but is it getting INTO the carb? If fuel is getting into the carbs in the appropriate quantity, then the problem is that it isn't getting back OUT, due to clogged jets.

    I'm interested to see how your float valves are working - two more checks first, to help narrow down the issue:
    1. You say it takes ~ 15sec of cranking after it stalls out. Try this - start it, warm it a bit, then get ready to ride like always. When it stalls, don't crank it - just sit there for a minute, watch the pretty girls walking past. After a minute, try again - does it start right up?

    2. As before, get it started, warmed, then try to ride off. AS SOON AS IT STALLS, turn the fuel tap to OFF - don't forget to switch off, too!. Stick a little bowl under each carb, then open the carb drain screws one at a time, draining the fuel (don't forget to close them back up again, finger snug!) You should get 2-3 shot glasses worth out of each, but I'll wager that one or two give you much less.
     
    dontz125, May 11, 2011
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  7. dustyjax

    dustyjax New Member

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    thanks mate,
    The first one when It stalls and wait for a bit it starts up no problem.
    for number 2 will try that tomorrow,
    I have let the bike idle for 20 mins and rev it every couple of mins and it runs fine until I try to ride it.
    what parts do I need to do a carby rebuild? would the local yamaha dealer have the parts I need or is it just easier to just get the dealer to do the work.
    Cheers mike
     
    dustyjax, May 11, 2011
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  8. dontz125

    dontz125 Active Member

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    Right now you aren't doing a carb rebuild - you're doing a carb CLEANING. Big difference. Nothing should be considered for replacement at this point.

    Taking it to a mechanic is a waste of $300. Do it yourself - it's not hard, and it'll get you used to working on your twenty-year-old bike! Read the carb clean & sync threads here and over at FZROnline, figure out what cleaners you need, and go to the local hardware shop to find what you need for a carb synch tool (that's in the threads too!)
     
    dontz125, May 12, 2011
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  9. dustyjax

    dustyjax New Member

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    hi mate,
    put undid the screws at the bottom of the carbies and got the same amount out of each one. took it for a run and still the same but I was able top stop it from stalling by trying to rev it but would not rev up , do you think it needs a pump it sound like it aint getting fuel in to the float chamber quick enough to keep running the fuel line looks like it does doen to the tap than it comes back up through the filter to the carbs.
    mike
     
    dustyjax, May 12, 2011
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  10. SnowFox

    SnowFox New Member

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    Gravity feeds the bike pretty well, ive run both mine without a pump.

    Recheck filters, including the AirFilter, make sure the AF is sitting snugly on the carbs, the tiniest gap left me stranded for half an hour until i found it.
     
    SnowFox, May 12, 2011
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  11. dustyjax

    dustyjax New Member

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    hi mate,
    just changed the fuel filter again now there seams to be full of fuel compaired to the last one which was a new one 2, the air filter is old and dirty and the rubber seal around it is split. waiting till tomorrow to get one of those unifilters.
    hope it works.
    Cheers mike
     
    dustyjax, May 12, 2011
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  12. dustyjax

    dustyjax New Member

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    hi again
    I have pulled the carbys apart and cleaned them, lots of crap in them.
    got the bike started but the problem is still there.
    Would the balance of the carbs be the problem now as when I go down hill it goes to 30 km in first gear but when I go up hill it dies. do I need a fuel pump as yamaha wants $400 one and I cant find one from the wreakers.
    Please help.
    Mike <!-- s:( --><img src="{SMILIES_PATH}/icon_sad.gif" alt=":(" title="Sad" /><!-- s:( -->
     
    dustyjax, May 20, 2011
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  13. dontz125

    dontz125 Active Member

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    Put a length of clear line on each carb drain port (one at a time), and crack the drain screw with the ignition and kill switch on but the engine off - you're measuring how high the fuel gets vs a cast-in measuring line. I *think* it should be 10.5mm above this index line.

    You're still dealing with starvation, and tuning info on these bikes is hard to come by and sometimes harder to interpret. If I'm right that the fuel level should be 10.5mm above the line, and some previous owner set it to 10.5mm BELOW the line, then yeah - it ain't gonna work too well...

    Once that's set, look for your mixture screws beside the bottom of the bowls. They should be set around 3 turns out from fully in - DON'T crank them in, just turn them in until they lightly touch, then back them out.
     
    dontz125, May 20, 2011
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  14. dustyjax

    dustyjax New Member

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    thanks mate check that tomorrow, the mixture screws are stuck, tried turning them just before. Think this bike has been sitting for some time, just want to get on the bloody thing and ride.
     
    dustyjax, May 20, 2011
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  15. dave

    dave Well-Known Member

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    Have not had much of a chance to read the posts on the forum during the last week but noted you asked about the exup valve.

    When I bought my FZR it had the valve wired fully open, that is clockwise looking from the gear lever side of the bike.
    My cables were missing.

    Mine had more torque at low revs when it was restored to operation.
     
    dave, May 20, 2011
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  16. dontz125

    dontz125 Active Member

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    Good point - I had lost track of this. Where do you have the valve right now? Have you tried adjusting its position now that the carbs have been cleaned some?
     
    dontz125, May 20, 2011
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  17. dustyjax

    dustyjax New Member

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    Hi guys,
    I got a secondhand set of exup cables and they all work fine now set the valve as per other posts about it.
    I am going to look at the float levels again today, as I had a ute once that ran like my bike now and it was the needle and seat playing up.
    will post again later.
    thanks for your help guys
    mike
     
    dustyjax, May 21, 2011
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  18. dustyjax

    dustyjax New Member

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    hi
    I have been reading some posts on this forum about spark plugs,
    I couldn't get CR8E plugs only Cr9e would this also be a cause of the problems with this bike,
    All the float levels look ok to me, I have ordered some new needle and seat parts and seals and a fuel pump just have to wait till the arrive now.
    Cheers Mike
     
    dustyjax, May 23, 2011
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  19. SnowFox

    SnowFox New Member

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    I had really **** performance on the CR9E's.
     
    SnowFox, May 23, 2011
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  20. dustyjax

    dustyjax New Member

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    hi snowfox,
    I read that somewhere on here and got me thinking.
    going to change the plugs and see how she goes then.
    cheers mike <!-- s:Biker1: --><img src="{SMILIES_PATH}/th_Biker_1.gif" alt=":Biker1:" title="biker_1" /><!-- s:Biker1: -->
     
    dustyjax, May 23, 2011
    #20
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