Troubleshooting My Bike Xv 750 (Virago)

Discussion in 'Technical' started by mbox999, Jun 16, 2010.

  1. Hi ,

    I was just testing my restored Yamaha XV 750 (virago ) today...not all is as it is supposed to be (yet...partially because there are some "cosmetic"parts missing) and one of the "faulty facts" is when i try to accelerate from 140kph up on 5th gear the clutch seems to "slip"....the rev willl go up but not the speed...but the mechanic ( who is fairly trustable) explained that he exchanged the clutch ..anything else i must look at to trouble shoot?

    My virago has a new custom made exhause which really sounds great...but the bike merely "burbles" (Not really backfiring) when i reduce the accelerator , what is your suggestion to work it out ...or is it a rather harmless? Thank you,

  2. Reinhard, did he only change the clutch plates, if so he should have also changed the springs (they get weak over the years), if they are too weak clutch will slip under strain, considering high speeds and the wind resistance, that's where it will happen, try 2 up and it also should slip under heavy acceleration. New springs you can order from Craig-EBC. Did he fill semi synthetic or mineral oil ? If fully synthetic, clutch could slip too.
    Backfiring and bubbling comes from wrong adjusted carbs and sometimes also from not well adjusted valves. The latter I don't think as he for sure has adjusted the valve clearance right. Ususally on V-twins the main jets in the carbs are different sizes, did he swap them ?? Just take out the sparkplugs and check them for an even brownish colour. If one is white and the other black (on the ceramic body that holds the inner electrode) then the swap of jets happened. That's a rather delicate matter and great care & "by the book process" should be taken & done. I had this problem occurring on the Bros too. Also the floatheight of the carbs should be adjusted to factory settings. Another reason could be opening up the airbox here the carbs also need adjustment. Check also if the main jets still are the right size or Somchai has put in others (will need a magnifying glass to see the numbers). I played around with the DR650 carbs a lot in stopping her popping while decelerating while fitting the Dynojet kit, takes some time to get the right adjustment and perfect ratio air-petrol-exhaust.............
    Carb adjusting is a delicate matter and needs you to work methodically, one by one and always try when you did try to adjust one thing, takes time and patience. Don't rush it, rgds, Franz
  3. Thanks franz...the spring sounds logic and will have it checked out. About the bubbling...i think it has something to do with the exchanged Carburator.
    Have to say that the restore on the Bike wasn't all that great...the Bike is a lot better than before but i was expecting a bit more, but than again maybe my "expectation" was just too high?? I had other choices such as Piston Shop which would probably my choice if i have another restoration in mind .

    happy trails,


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