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XVS 650. Jetting and Carby???

Discussion in 'Maintenance and Servicing' at netrider.net.au started by Randall, Mar 1, 2013.

  1. I cant find any answers after a search so I will ask.

    I recently purchased a 2005 Yamaha XVS 650A. Classic. Its at 17,000 klicks and in pristine condition both mechanically and visually. The fellow I purchased it from told me it has been rejetted and dyno tuned. (Got all service receipts so he wasn`t lying) It also has some real nice V&H pipes. (Sweet!!) It really develops a lot more torque than a standard XVS. Quite amazing really.
    However, today I fired it up to go for a quick blurt. It is not cold. (Brisbane) It always likes full choke for the first 5 seconds or so with just a little throttle. Today I gave it a handfull to early and it wouldn`t start. I could smell fuel so I obviously flooded it. After leaving it for 30 mins, back to normal again and it started first kick.
    My question is, does rejetting to larger jets and dyno tuning make it more susceptable to this issue? Is there any strategies for better starting? It is due for its 20,000 klick service soon. Will I need to have it dyno tuned again?
    Any advice would be gratefully received.
  2. The standard xvs650 appear to be jetted lean from factory, so they normally really love their choke. I've seen a couple of them blister the paint on the RH side cover where the rear cylinder exhaust pipe goes past. I suspect this is because the pipe gets too hot from running too lean. If given oportunity I re-jet to cool pipe down by fitting one size larger pilot jets. (It may also be caused by the pollution system bleeding air into exhaust, but thats another topic)

    Sometimes if they have increased the pilot jet size so that the bike is running a little richer than standard, the bike may require less choke to begin with & you may need to push choke in sooner after startup.

    If it was a warm day & the bike had been run a few hours ago so was still slightly warm, it may not have required any choke at all, and if you did use choke in this situation then it might have been too much for it.

    Sometimes when bikes are jetted on a dyno, the operator is mostly concerned with full throttle tuning, and pays little attention to starting & low speed operation, so the bike may benefit from having the carbs balanced & the mixture screws fine tuned at its 20k service.

    sometimes modified bikes have the odd little hiccup, when weather conditions and operator error combine, and there may not be really anything wrong.
    • Agree Agree x 1
  3. Thanks for the detailed opinion my freind. You have made me feel a lot more confident theres no real issue here. It all makes perfect sense. I didn't know the dyno tune guys calibrated to the wide open throttle rather than the lower rev end.
    The last paragraph says it all :) operator error and weather conditions may be the problem. Ill get the next service with all this in mind. Thanks again for the heads up. Appreciated.
  4. Just following through.....been a few days since the "flood" and all is back to normal. I have worked out what this particular bike likes for problem free starts from cold and am sticking to it!!