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REPETE'S XS650B Preservation Carburetor

Discussion in 'The Garage' started by REPETE, Oct 31, 2019.

  1. thuban

    thuban Horse Scratcher XS650.com Supporter Top Contributor

    "According to a poll conducted by the American Association of Shadetree Mechanics, 80% of reported carburetor malfunctions originated in the ignition system, 10% were due to absence of fuel, 3% originated in the valve train, 3% were due to cylinder condition,and 1.5% were due to lubrication failure."
    gggGary likes this.
  2. grizld1

    grizld1 Grumpy old man Top Contributor

    Right you are, 5twins--looked again, and I can see the slide behind the object I took for the needle. Sorry, Repete, had a brain bubble working its way through....
    gggGary likes this.
  3. thuban

    thuban Horse Scratcher XS650.com Supporter Top Contributor

    I'm going to add to what gggGary said about proper synch of your carbs. This is very easy and the carb butterflies will be matched almost perfectly. Can only do it this way with carbs off. Once your carbs are back together and ready to mount on the engine, look into the engine side of the carbs. Crack the butterflies and notice the three little holes in the top of the housing above the butterflies.
    Turn the idle adjusting screw on the left carb out until the butterfly is fully closed. ( no pressure on adjusting stop from the idle screw)
    Look at how much the left butterfly covers the first hole ( should be half or more of the hole covered off, the other two holes not visible)
    Turn the middle carb adjusting screw to adjust the right carb butterfly to match the hole covering of the left carb and your done. You'll see it's really exact.
  4. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    That works great on linked carbs :sneaky:
    thuban likes this.
  5. thuban

    thuban Horse Scratcher XS650.com Supporter Top Contributor

    I take it his aren't linked? Ohhhhh, dual cables!! Who says you can't teach an old dog new tricks!
    gggGary, you da' man!
    gggGary likes this.
  6. XSLeo

    XSLeo XS650 Guru Top Contributor

    On the bench holding the carbs up to a good light so it shines around the throttle plates and adjusting both plates to have the same amount of light around them isn't a bad place to start.
    Another way if to back out the idle speed screws till they don't touch the throttle. Turn back in till they just touch then three turns more gets you close.
    Once on the bike This should get the bike to idle. I like to do the next steps with out the throttle cables hooked up.
    With points at idle remove the right plug wire. This kills the right cylinder. Adjust the left side idle speed slowly down till it just stalls.
    Reattach the plug wire, start engine. pull left plug wire adjust the right side idle down till it just stalls. Now your carbs are in sync.
    Reattach plug wire. Start engine. It will idle high now. adjust both idle speed screws the same amount to get an idle speed of 12 to 1500 rpms.
    Now I hook up the throttle cables. Now while watching the left side throttle on the carb feel the right side. Hard to watch both sides. Now slowly open the throttle You should feel the right side start to move at the same time you see the left side.
    Adjust with adjusters at throttle grip. As you adjust the cables be sure to allow about 1/8 inch free play before cable pull carb.
    Now with bike running turn bars full left to full right several times. If the engine speed changes any at all loosen both cable the same till the engine speed doesn't change as you turn bars left/right.

    REPETE XS650 Enthusiast XS650.com Supporter

    YES.... correct.
    I was referring to that tube that is in front of the slide and behind the butterfly

    REPETE XS650 Enthusiast XS650.com Supporter

    BTW... I failed to accomplish much of anything on my "to do list".
    All of the input is valued and I'm anxious to get to everything... but the weekend was just too short and I "needed a win" - so I finished this project up and got it off my even bigger "to do list".
    Definitely off subject, but thought I'd share.
    This'll be my last ever post of a non XS related subject. Promise.

    IMG_4840 (2).jpg

    I now return my own self hijacked thread :gun: :hijack:
    lakeview, Mailman, Scottrt and 3 others like this.

    REPETE XS650 Enthusiast XS650.com Supporter

    Good stuff Leo, thank you.
    The only issue I'll have with this is that currently the right cylinder isn't firing at less than approx. 1800rpm.
    Earlier I established my check list of what I need to review and will be adding this as well.
    I am going to pay close attention to the ignition... points, condensers and the advance shaft in particular.
    One thing I didn't share earlier is that my initial goal of "just getting the motor to run" and then putting the bike aside for future project gave way to my enthusiasm that I could actually ride it with a little work... which ended up being a lot of work. In my exuberance, I never went back and installed new points and condensers. I simply filed, cleaned, set gap & timing and checked for spark.
    So, I will be changing those out. But being that I've got spark and the right cylinder does run great once it fires (above 1800rpm) I focused on the carburetor and now a suspicious eye towards the advance shaft.
    More to come in the upcoming days.
    Thank you
    Team Junk, grizld1 and gggGary like this.
  10. Team Junk

    Team Junk XS650 Junkie XS650.com Supporter Top Contributor

    Loved my mini enduro when I was a kid. That black with red accents still makes me lust for the 360 that had that color pattern. They sure look great. I personally don't mind none xs posts. Self hijack away.
    gggGary likes this.
  11. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    gggGary likes this.
  12. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Yup unlike many forums, no Dictator moderators live here. Just us plain folks enjoying each other's company. Wander as you will it just adds to the fun.
    JAX71224 and Team Junk like this.
  13. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Good Day All -
    I managed to get a couple of things done last night.
    The brass nipple I showed in a previous pic has been polished and adhered back into the carburetor. It's not going anywhere now.
    Also, I extracted the Advance Rod using the Clymer book as my guide.
    Unfortunately, the book addresses the removal from a perspective of a motor tear down - not so much as a maintenance item.
    So, I've kinda lost focus of my mission and wanted to check in before I go further.
    I removed the points mounting plate and the Points Cam off of the Advance Rod end. Then I removed the Points Casing exposing the camshaft bearing. Gasket tore in the process so starting a new "need" list. I used a needle syringe to inject grease into the bearing and then moved on to the Advance Mechanism Cover on the right side and slid the shaft out.
    I stopped here because I'm not clear on what I'm looking for. I see nothing that I'd consider out of the ordinary. Shaft was straight. No gouges or rub marks. It was very clean. The Advance Mechanism appears to function in that the springs are in place and the weights move freely. I don't know if I'm supposed to be disassembling it and if so why. To get to the Cam Shaft Bearing for lubrication?
    I'm thinking it'll probably be a good idea to replace the points cam. To me it looks a bit worn and I see that MikesXS has them. They also have the points BUT are out of stock on the condensers. Seems to me that If I'm addressing the ignition system I may as well do it all... soup to nuts. I'll check eBay for the condensers.
    But the big question is... what am I looking for on the Advance Rod and Mechanism that would have an effect on the right cylinder not firing below 1800 rpm?
    I may not be seeing the forest through the trees. :shrug:

    EDIT: I see that MikesXS has a spring set for the Advance Mechanism and it says in the description that weak springs can affect timing at low rpm's... so I've added that to my order.
    IMG_4851.jpg IMG_4853.jpg
    Last edited: Nov 5, 2019
    grizld1 likes this.
  14. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    That doesn't look bad, what I found (typical) on one I was just working on.
    A clean up, lube and resetting points cleaned up stubborn funky idle issues.
    If your springs aren't loose at rest and a timing light shows good smooth advance action you are better NOT using those mikesXS springs, lots of sad commentary from those that have..... do a search on advance springs for options. Especially with electrics? chinese copies of OEM parts may not live up to expectations and create problems of their own, hint points,.... If you can get .014" points gap and timing within the adjustments your points cam should be OK. Also do a search on advance weights to see some of the issues that can occur there.
    grizld1 likes this.
  15. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    UGH! I JUST ORDERED! :doh:
  16. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    well that's too bad there is lots of info here on what and what not to use from there.
    the fingers that fit in the slots on your advance weights look a bit worn.... There's threads, read them!
    grizld1 and GLJ like this.
  17. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    I just cancelled the order.
    I have been reading first rather than just asking. What I found on Advance Rods had more to do with folks worrying about screwing up timing on re-installation,trying to locate one for sale, etc. Couldn't locate something addressing a "general servicing" and lubrication(?).
    It may well be there, but I'm still learning the site and I couldn't find something more specific to what I'm doing.
    I will look further as time permits.
    I see there are Dalichi Brand (made in Japan) point sets available on eBayas well as Yamaha.
    gggGary likes this.
  18. 5twins

    5twins XS650 Guru Top Contributor

    For servicing the advance rod, you don't need to remove all the stuff you did. Just pull the nut and little disc off the advance side, then slide the rod out the points side with the points cam still on it. Take care not to lose the little locating pin for the advance disc that's stuck in the rod. I usually remove that too while the rod is still in place and put it somewhere safe.

    The advance rod rotates in the cam a small amount when the ignition goes from retard to full advance and back. This is why it needs to be lubed, so it turns freely through this range and back again. If you look in the hole in the cam after you pull the rod out, you'll see a bushing in each end with grooves in it. Those grooves are there to hold grease and provide a reservoir of lube for many miles and years .....


    Clean any remnants of old grease out of there (you probably won't find much, if any), and pack it with fresh stuff. The factory shop manual recommends a grease with moly in it .....


    Clean the advance rod and smear it's entire length with grease. This is more for corrosion protection that lubrication purposes. The rod is just raw steel and could rust up if water made it inside the cam somehow.

    There's one little "gotcha" to watch out for when re-assembling. The hole in the rod on the advance side for that locating pin goes all the way through. That means the pin could be installed in two different positions 180° apart from one another. Only one is correct, the other will throw the timing off 180°. You need to align the pin with the pin on the other end in the points cam, so they both stick out the same side of the rod .....


    To help with this, there's also some alignment slash marks on the advance unit and the little disc. They should point to one another as well (yellow arrows) .....

    gggGary likes this.
  19. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    THIS is extremely helpful and appreciated.
    Trying as best I can to help myself I did more digging on the forum this morning and I found this little diddy from back in 2010....

    I've been so completely distracted by this today that I went home for lunch so I could take a closer look at mine. One of my springs is lacking "spring" as compared to it's counterpart.
    So, now to find springs. My first choice would be OEM NOS.... but parts diagrams don't list them.

    Additionally, I'm looking at the Advance Disc and am wondering if this too should be replaced. :umm:
    But, never having seen a new one I don't know if I'm seeing wear or I'm seeing an "offset" design feature.
    Take a look....

    You have provided me with wonderful information. And apparently you've been doing this for others for a very long time!
    This is copied from a thread I found on the forum....

    5Twins (2010 post)…. “Once you have removed the advance rod, if you look into the holes in the cam end, you'll see the outer bushing on each end has grooves cut into it's I.D. Fill those with grease and the rod will have a reservoir of lube for many years to come. Even though the ends of the rod are the only spots that really need lube, I smear the entire length with grease to protect against corrosion - just a very light smear so it looks wet.
    The ATU itself can also use an occasional lube job, specifically the posts that the weights rotate on. Initially, I pull it apart, clean the posts & weight holes, then lightly grease. After that for maintenance purposes, I use a small shot of foaming chain lube on the posts and springs occasionally. I apply it when the motor is warm so it penetrates better.”

    I'll be printing this out to add into my shop manual.

    Now that I have clear direction on proper reassembly of the advance unit and proper lubrication I'll need to focus on replacing worn parts... the springs and possibly the Advance Disc.
    Points are available from Partzilla (Ca-Ching!!! $$$) as well as the casing gasket(s).
    I'm not sure if I should be worried about the capacitors or not.

    gggGary likes this.
  20. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Do a E-Bay search for 256-81654-10-00

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