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want to confirm next steps after smelling gas from oil filler opening

Discussion in 'XJ Technical Chat' started by kosel, Mar 27, 2017.

  1. kosel

    kosel Active Member Premium Member

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    Sorry for the long post, but I wanted to err on the side of providing as much detail as I could.

    Also, thanks in advance to every for their help. I'm quite handy, but not really a motor guy. Since buying an older motorcycle, I've had a chance to learn a ton and your expertise and encouragement are appreciated.

    The background:
    I picked up a 1982 XJ650 Seca in autumn 2016 from a shadetree mechanic that works only on older bikes. Rode the bike the rest of the season without any issues. To winterize it, I made sure the tank was full of treated, non-oxygenated gas, I ran the bike a bit to get it into the system, shut it down, drained the carb bowls and topped up the tank. Put a tender on the battery and put it to bed for winter.

    In February, we had some record weather and I started it up and took it out for a spin. It didn't fire right up, but it didn't take much coaxing, either. I did not notice anything to indicate any problems.

    The symptoms:
    Weather got cold again and after sitting another month on the battery tender, I fired it up. No, I had not re-drained the carb bowls. It started well enough, but got a bit rough as it warmed up and was incredibly sensitive to choke and throttle. Exhaust 1 & 2 were cold, so I shut it down and pulled the plugs. They were wet. I left them out to dry things up, started searching on the forums, and can confirm I smell gas in the crankcase. So, if I read anything correctly, I likely have stuck floats on carbs 1 & 2.

    I want to add that last fall, a friend's Honda CB350Four had two cold cylinders after we cleaned and reinstalled his carbs. That evening, when I started mine up, I felt the exhausts. 1 & 2 were cold while 3 & 4 were warm. But, 1 & 2 caught up and were eventually hat and the bike ran smoothly.

    Next steps:
    I plan to rebuild the petcock and then address the carbs (rebuild/clean/set/synch).

    Questions:
    Anything else I should be looking at?
    I have heard people talk about tapping float bowls to release the floats, any more detail as to what this means or when its necessary?
    When I put the bike on prime to get it going after draining carb bowl, how long should I be on prime? Should I automatically tap on the bowls? Put another way, how do I prevent this when I reinstall the carbs or next spring?
    I assume I should immediately drain and replace the oil.

    Thanks again.
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    tap or rap the float bowls with a screwdriver handle when first filling them to make sure they do not bind as they rise with the fuel.
    prime 15 to 20 seconds close and repete. I would advise using translucent fuel line so you can see when the bowls are full (no air left in line)
    I run the last few tanks of fuel for the season with non ethanol high test and do not drain the bowls you can add your brand of stablizer if you want on the last tank fill.

    as long as you can see an air bubble in the sight glass do not drain the oil until you can confirm your carbs are not overflowing then change oil
    unless it is going to be months spring is just around the corner
     
  3. Jetfixer

    Jetfixer Well-Known Member

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    Do not leave petcock in PRI if you have stock petcock. Leave in ON if it is still vacuum petcock . As long as it is not leaking this should keep you from filling crankcase .
    ^^^+1 tap float bowls with handle of screw driver see if it helps.
     
  4. Toomanybikes

    Toomanybikes Well-Known Member

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    And replace the oil and filter AFTER you fix the fuel problem
     
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  5. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    And don't start/run the engine until you have fixed the fuel problems!
     
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  6. Polock

    Polock Well-Known Member

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    your original rubber brake line
    if you had a clear inline fuel filter you'd know right away
    check the oil level, if it's only up a few ounces, you can start it to work on it. but change it before you ride it. you might not fix the floats the first attempt, then you wasted the oil
     
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  7. kosel

    kosel Active Member Premium Member

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    Parts from XJ4Ever are on their way and I spent time today getting the bike ready. I hope I can get it running smoothly again. Today was the nicest weather since last October and I had to resort to riding a friend's Honda.
     
  8. XJ550H

    XJ550H Well-Known Member Premium Member

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    got 10 inches of snow last night:(
     
  9. kosel

    kosel Active Member Premium Member

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    My sympathies. I'm in Minnesota. Snow will remain a possibility for a couple more months.
     
  10. Toomanybikes

    Toomanybikes Well-Known Member

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    Beautiful day here, had garage door open while working on a bike.
    13c and sunny
     

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  11. kosel

    kosel Active Member Premium Member

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    I just started a new job, so progress has been slow. I'm in the middle of rebuilding the gas tank cap and the petcock valve right now. With everything going on, it'll be a bit before I tackle the carbs.
     
  12. kosel

    kosel Active Member Premium Member

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    I finally cleared up some time where I could focus on the bike and get the carbs off. This was my first time removing the carbs (on anything) and with everyone's tips on heating and loosening the air box and tucking the boots in, it took me a lot less time than I feared to remove the carbs. As well as it went, there are some things I wanted to run past this group:
    • Some of the clamps were incredibly loose and most of them are bent in some way. Assuming I can tighten them up well enough, do they need replacing?
    • The carb boots are flexible enough and I don't see any cracks, but they are caked with thick grime and grease. What's the best way to clean them?
    • The bike ran great last season and I was planning to do just to the carb lowers to cut my teeth and save a full rebuild for this fall. I'm the farthest thing from an expert, but the guts seem to hint at biting the bullet and do the full rebuild now. Thoughts?
    Thanks in advance.
     

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  13. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Not a bad idea, but those carbs look remarkably clean inside, any history known about their service record?
     
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  14. kosel

    kosel Active Member Premium Member

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    I don't have any history on service. I bought the bike from a mechanic that was actively riding it on weekends. This was one of the newest bikes in his shop.
     
  15. kosel

    kosel Active Member Premium Member

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    I think I measured the valve shims correctly and have identified the replacement shims I need.

    Intake
    (carb; clearance; current shim; replacement)
    #1; 0.09; 285; 280
    #1; 0.10; 285; 280
    #1; 0.10; 285; 280
    #1; 0.09; 285; 280

    Exhaust
    #1; 0.18; spec
    #1; 0.16; spec
    #1; 0.14; 275; 270
    #1; 0.18; spec

    Is it common for all the shims to be the same size? I was wondering if it was possible they are original. The bike has 23k miles.
     
  16. Nuch

    Nuch Well-Known Member

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    Are we talking clamps on the intake side or the air box side? When I had the carbs off last season, I noticed my air box side clamps were loose even when the tension screw was completely against it's nut. I took an old bicycle tube and cut strips the same thickness as the clamps. Then I used contact cement to bond the rubber to the inside of the clamp, effectively lining and thickening the inner diameter of the clamp(s). Worked like a charm!

    I'd imagine if the PO was a MC mechanic, he'd have checked the shims and swapped the ones that needed changing... but you never know...
     
  17. kosel

    kosel Active Member Premium Member

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    The clamps for carbs 2, 3 & 4 on the airbox side and the clamps for carbs 2 & 3 for the intake side. I'm guessing someone was too lazy to reach in there and find the screws.

    As for the mechanic, I think his focus was making them run, not necessarily the fine details. Still, I was happy with it before I started digging into it; I'm hoping it's even better when I'm done.
     
  18. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Unlikely. The most common way for that to happen is an idiot (make tham all the same, paying no attention to the clearances). The second (and more desirable, but quite rare) most common way is the head having been built by someone who's really, really, overly, incredably focused on getting things too perfect. In order for all the shims to be the same size, and have all of the valve clearances in spec, a fella would have to grind the valve stems amd/or be really (pointlessly) accurate when putting in new valve seats.


    I just thought of another way. If somebody had a bunch of the same size shim, but not any of the sizes needed, that fella might grind the shims to suit. Check the shim thicknesses with a micrometer or caliper.
     
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  19. kosel

    kosel Active Member Premium Member

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    I was getting ready to replace the valve seats and noticed a distinct difference between the old ones and my replacements from Chacal. The replacement (on the left) is 13.75mm tall, while the old on (on the right) is 15mm. Also, the size of the fitting on the end for the screens are completely differ shapes and size.

    Can anyone tell me which is correct?

    Also, the old valve cover lifted up easily, leaving the gasket stuck fast to the engine. Any tips to remove it? I don't want bits of gasket to get into spaces it doesn't belong..
     

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    Last edited: May 11, 2017
  20. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    I can, me, me (waving hand wildly in air, in the back of the room)!
     
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