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sr500 refuses to start

Discussion in 'Bling and Appearance' started by thecptn, Jul 3, 2007.

  1. Mate of mine just bought this sexy, sexy, sexy (lol) sr500 cafe racer, pics soon, how ever, the old girl wont start, this is a kickstart motor too, we changed the plug, put fresh fuel in, and nothing, it will fire over and hold it for about 3 seconds before shutting off, putting on throttle will just shut her down, we have fiddled and faddled for 3 days now, and we just cant get it on, the carb seems to be getting fuel, checked the air filter, its okay, we checked for spark, plugs are sparking, we are so stumped!


  2. Float level OK?

    Does the fuel tap have a vacuum line to the carby? that may be blocked, and not opening up the tap (try putting the tap on "prime" if it has that selection)

    Also, try to remove the fuel tap and see if it's blocked.

    When it dies, rip the plug out, is it wet or dry? That'll tell you if it's flooding or starving.

  3. another thought... is it the original carby? those things wear out and leak a lot of air around the piston, making starting hard at the best of times.
  4. Is the choke working properly? Don't use any throttle when trying to start it.

    SR500's can be temperamental to start from cold, at least until the bike's 'character' is learnt.

    Kickstart technique has a lot to do with it.

    Edit: Has it got a hot start switch? Make sure it isn't set to 'on'.

    For more info:
  5. Well..let me tell you about this thing, what the previous owner told us, was the motor has had some work done to it, he mentioned high compression and some other doodle dalleys, the only way we can get this to run according to other owner, is to start it when the carb is dry, so fuel tap off, kick it over, once going, fuel tap back on, how ever this doesnt work as we found out, after some fiddling, the only way we could get it to fire, was by placing the choke on, kick it over, than place the choke off, and it would fire for 3 seconds and die.

    We did notice the plugs where quite wet, and also it kept flushing out small amounts of fuel out of the fuel drain bowl hose, each time we tried to kick it over, so it could be flooding, I am not sure if the carb is an original, I know its one huge mofo Mukini which sounds like godzilla breathing.
  6. I'd check the float level, that could explain the flooding, and definitely the fuel running from the float drain.

    Makes it hard when it's been "fiddled with", by persons of "unknown competence" before you've been trying.

    Reset the float level for sure, then try again, this time choke full on for one priming kick, then choke off and another full blooded kick to start. That bit about a "dry carby" to start sounds shonky, like it's needle and seat is not seating properly, or the float level is way off (or both).

  7. Well, a bit of an update, the carb was taken off to be cleaned and rebuilt, last I heard about it, it was chokers full of old fuel crap, it should be on today, hopefully it should work again.
  8. check your idle cables :shock:
  9. If u can. Check all the jets are the correct ones. Some engine mods might have been previously done and removed, leaving the jetting way off.
    Also check the choke plunges, and the throttle slides.

    Kick starting can be a right B&&*H :p :p i know how u feel.
  10. Sounds like carb at fault... good luck with it after the carby clean
  11. Well after getting the carb back, it was put back on, and eventually...it starts and stays on! woohoo!
  12. Sounds like perfectly normal behaviour for an SR500. Yamaha were careful to design it to be impossible to kick start, whilst failing to provide an electric boot. This was to prevent customers from actually riding this attractive and promising machine and finding out how disappointing it was .

    Seriously though, the SR isn’t as bad as its critics make out, and if you can get it running reliably it’s a pleasant, characterful, although not terribly fast or refined ride.

    They’re all pretty long in the tooth now, so anything could have happened to it over the years.

    If you can make it run at all, your kickstart technique must be, at least, workable and will improve with practice. I take it you know about lining the mark on the cam up with the window in the cover.

    That carb doesn’t sound original. A mate’s SR had a horribly complicated thing with jets by the hundred and accelerator pump linkages all over it. Horrible device. I could have forgiven it if it had had some beneficial effect on the performance or fuel economy, but neither was significantly better than another mate’s BSA B33 500 single with its stone-age Amal.

    A big slide Mikuni should be a much better bet if set up correctly. The wife had one on her Commando and it was brilliant. Ultra reliable, fantastic power and flawless throttle response. Shame about it inhaling next-door’s chihuahua when it got a bit too close though :grin: .
  13. Thanks Pat, sadly the bike belongs to my friend, I am quite envious of this machine, for any one who wants to know, its the red cafe racer sr500 that used to belong to the Road warriors cafe at mt white, if you go there it aint there no more, ill post some pics up soon.
  14. ahhhh rad, that thing looks nice