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Yamaha XVS650 lagging when accelerating

Discussion in 'Maintenance and Servicing' started by Ash_173, Aug 12, 2013.

  1. What started as a supposedly simple carb cleaning issue has become a saga :(

    About 6 weeks ago my bike began lagging on acceleration and would surge when the throttle was opened.
    So I pulled out the carbs, gave it them a good clean as they were quite filthy with what appeared to be a red/brown gunk.
    This did not fix the issue, so as I was in a very busy period had it picked up by Peter Stevens in Geelong. They had it for over 3 weeks, charged me almost $1000 and didn't fix the issue :mad:
    In this time they also checked and adjusted the valve clearances. They claimed that it needed a new fuel pump and would cost a further $500-600 to fit one. So I got one and fit it myself. This did not fix the issue.

    So I took it to Road and River in Geelong, who charged me over $300 and said it was fixed, that it only required a carb balance and the mixture screws set back to factory (which I had already done), they also adjusted the float levels. They also said the ignition coils were not testing properly.
    So I replaced those as well.

    So the Yammy is still lagging/bogging under engine load, backfiring, surging and cutting out if I don't take off carefully.
    My next best bet was an old mechanic who still works on Japanese bikes in Geelong, but he had a heart attack yesterday (which is a fair reason to take some time off). So now I'm well and truly neck deep in the proverbial creek.

    I don't know how to proceed. Has anyone had similar issues?
    • Like Like x 1
  2. of course its an impossible guess, i would have a think about ignition leads
    and check voltage at idle and revs n shit like that
  3. What do your plugs look like ? Are they clean and grey ? Check the gaps. The only other cause I've seen for this is needle adjustment, but everyone's already been there.
  4. you removed main jets when you cleaned carbs ???
  5. Check delivery of fuel from the tank, check any breather hole in the cap.
  6. The plugs have been replaced multiple times, but are coming up fouled each time. Coils and leads are replaced. All the jets were cleaned by myself and the mechanics, fuel delivery seems to be fine. What should the breather hole be like? It is quite small but seemed clear.
  7. Might be the lack of HP
  8. Yeah, hehe, I'd love to go up to the 1300. But in the mean time I need to get this one moving properly again!
  9. Hi Ash,

    Just a shot in the dark (often the best sort on cold winter nights in a stable) but there is a chance it maybe related to the exhaust. If the pressures are not right for the gas to escape can cause problems with firing. May pay just to have a gander at the pipes, or if you have recently put on new pipes or had some work done in that area work a look.

    Let us know when you find the problem anyway, fingers crossed for you.
  10. Would that cause one cylinder to not fire correctly?
  11. Does it run okay on start up and gradually gets worse when it warms up?
  12. What fuel do you run?
  13. It runs crapy from the start, if too much load is put on the engine it will cut out, it gets a little better as it warms up but still crap.
    I've tried running 91, 95 and 98 from BP. It doesn't seem to make a difference regardless of fuel type. I normally run 95 though.
  14. Only run 91. I had problems with my vstar running anything higher. Anything higher fouled the plugs. It might not be the complete solution but it'll be part if it. Drain everything, clean everything and only run 91.
  15. make sure you post the answer when you get there !.

    1 as above any mods been done recently/
    2 has the bike been in storage ?
    3 is there any more info that corresponds with the problem arising , i.e. when did you start noticing the problem and what happened around that time that might be relevant ?.

    have you tried fanging the fcuk outa of it ? ).

    maybe water in fuel -would that correspond to anything i.e. washing bike storage - condesnsation ?

    if so empty tank add some metho to absorb any water then fill up .- maybe try it anyway.
    • Like Like x 1
  16. I only run 95 as Yamaha states no ethanol. Most 91 has it but 95 does not. My XVS650A runs like a charm.
  17. ◘weird that , is SA 95 mostly has ethanol in it , never seen it it in 91 .
    I thought the ethanol was added to 91 to get it up to 95 spec.
  18. Ethanol is not Methanol. Methanol is added to up the octane level but Ethanol is added to make the fuel more "green". E10 is the most common 91 octane and most garages now only sell it. Non ethanol 91 is a little hard to find at times.
    • Disagree Disagree x 1
  19. I'll try flushing the tank, metho'ing any water out of it and running 91.
    • No engine/fuel/exhaust mods
    • No washing (has been in the rain though)
    • Has not been in storage and is a daily ride (my only transport)
    • I have had to basically be throttle completely open to get to 60km/h, this results in little mini speed surges
  20. Different states seem to have different types of 91. In VIC, I never used the ethanol variants of 91.

    FWIW - I had a similar issue when using anything above 91. The guys at city Yamaha said that 95 "fouled the plugs".