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1979 xs650 with a few questions....

Discussion in 'The Garage' started by dalelemons4, May 15, 2020.

  1. dalelemons4

    dalelemons4 XS650 Enthusiast

    1979 XS650, PMA, Pamco electronic ignition, no battery, kick only, mikuni round slides 34s.

    I just got this ride put back together and I have a few issues that are keeping me from being comfortable riding this thing.

    1. My advance shaft - When I tighten the nut on the advance shaft to what seems to be a good snug fit, the shaft will not advance. The centrifugal force will not open the springs when above 3200 RPM. When I loosen the nut to where it is barely on there the shaft will advance. I was going to just put a lock nut on there loosely and call it a day but something just doesn't seem right and I don't want to cause further issues. I feel as if I installed the ignition and the new advance assembly according to the directions so im just lost here.
    2. I got the external oil cooler mod kit and it is leaking like crazy. Again, it was installed per the directions I received but I cannot get it to stop leaking. I've torqued it properly from what I can tell but not sure if I have something incorrect here.
    3. I purchased the 34 Mikuni Round Slides and they came with a stock setup. 175 Main Jet, 15 Pilot, and a 6pF?? Needle I think. Anyways, I know I need to road test this bike and get the jetting and air screws dialed in but I was hoping to start with something close. I don't want to purchase a bunch of main and needle jets for testing if I can get it somewhat close. I live at 75' above sea level and it's hott (Tampa FL). I am running pod filters and cutoff exhaust. Cut just under and behind the stock foot pegs. The engine internals are bone stock. The bike runs ok now but I want to get it perfect so I am hoping that someone has a great starting point for me with these jets.

    Anyways, once I get this stuff knocked out I feel as if I can actually get out and ride this thing further than just around the block. Which is about all I feel safe doing at this point. Thank you all so much in advance for your help and support. Please let me know if there are questions you have for me and I can reply quickly.
     
  2. dalelemons4

    dalelemons4 XS650 Enthusiast

    Ok so I took the oil cooler back off and I noticed the gasket had some rough edges. I smoothed it out with some sand paper and then made sure it was super smooth and put some oil on it and reinstalled. I don't know if this will do the trick but I think it might. Still not sure what's what on that advance rod. I greased it and installed per instructions, or so I think I did.
     
    Team Junk likes this.
  3. 5twins

    5twins XS650 Guru Top Contributor

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    If your advance rod came from MikesXS, I think there have been issues with some of them being too short.
     
  4. dalelemons4

    dalelemons4 XS650 Enthusiast

    UPDATE

    The oil cooler is no longer leaking. The gasket had some impurities and once I cleaned everything it has been ok.
    I contacted Mikes XS today about the advance rod and I am hoping to hear from them soon. I'm still hoping to hear something about a good starting point for these carb jets. I'll keep plugging away. Thank you 5twins for the reply
     
  5. dalelemons4

    dalelemons4 XS650 Enthusiast

    Dang was hoping for a little more help lol but that's ok. Trial and error it is. I tried to take some material off of the advance rod but that did not work. I ended up ordering a new rod from Mikes and they appear to be exactly the same. I threw it in there anyway and sure enough, worked like a charm. Not quite sure why but I am happy it's working. So oil fixed, advance fixed, and for the carburetors I read the manual and some tuning guides as well as watched 3 hours of videos on Youtube and got it pretty close. I am running the needle on the middle clip, 15 pilot, 185 main, and the air screw 1 1/2 turns out. I have an issue with my throttle cables not being the same length so that has been a chore syncing them up. My buddy has some carb sync gauges so that will be my next step. UGH I should be getting paid to work on this thing. But she's getting really really close.
     
    YamadudeXS650C and GLJ like this.
  6. bikefreakjon

    bikefreakjon XS650 Addict

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    I think there are two reasons why you're not getting any help with your carburetor jetting. Number one is that there is already a ton of info for the stock mikuni bs34 s.
    number two is you don't exactly say what carburetors you have just that they're mikuni round slide 34 mm carbs.
    If they're mikuni vm34 is then I would suggest searching the forum for "carburetor jetting question mikuni vm34"

    Finally wear your air screw is adjusted is based on the preference of the individual bike and needs to be sad specifically for your bike not just to a designated setting.
     
  7. dalelemons4

    dalelemons4 XS650 Enthusiast


    Fair enough. Yes I have the VM34 Mikuni carbs. I really looked and looked and couldn't get a great answer in the text that I had read so I was hoping for a little bit of direction. I understand that there isn't really a perfect answer when it comes to these carburetors I was just hoping for a good starting point. But I will take your suggestions and try to be a bit more specific in the future. Thank you
     
  8. 5twins

    5twins XS650 Guru Top Contributor

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