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1982 XJ750 Seca - Ongoing

Discussion in 'XJ Technical Chat' started by Tim O, Jan 29, 2018.

  1. Tim O

    Tim O Active Member

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    I Think I got it???

    Pulled the carbs, which killed me. Promised myself I'd make it a year before I did that again... And found the small screens at the float valve seats were clogged.
    Took them all out, back flushed them with carb cleaner, cleaned out fuel inlet manifold, bowls, etc.

    Put it all back together and runs sweet in the garage... too bad no test ride until the rain breaks tomorrow night and then I'll know for sure.

    Fuel flowed freely through all bowls, air purged right out of the hose and gas filter, and when the bowls were full and bled the flow stopped nice and crisp, no leak by into the bowls... so something sure is different from cleaning those screens. (And the rest of the lowers...)
     
    Last edited: Sep 17, 2018
  2. Tim O

    Tim O Active Member

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    Oh yeah.... she's back. :):p:D:D:p:)

    50 miles of blue ridge parkway at 65mph... not a hint of trouble. So after all the plug changing, plug cap changing, tank cleaning, petcock messing and screen changing, gas cap disassembling and cleaning, tank cleaning, gas line and filter installing...

    It was four small screens in the carb inlets all along.:rolleyes:
     
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  3. Chitwood

    Chitwood Well-Known Member

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    At least now that you have an inline filter installed they should hopefully not be an issue in the future
     
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  4. Tim O

    Tim O Active Member

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    Wow the bikes been running so good it looks like quite a while since I needed a post in my ongoing log here

    But I'm now at about 20 thousand miles, just did an oil change and was going to adjust my clutch cable and linkage as its starting to get a little harder to go into second gear.

    It was like that before the oil change and I know it's a fairly common question around here, but can I hope to solve it with adjustment or is it almost always gearbox / shift fork wear?
     
  5. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    It's almost always a cable and/or friction disc wear issue (20K miles is about typical for clutch disc life). As long as you aren't banging a whole lot of 9000 rpms clutchless power-shifts, the gears/shifter forks will outlast the life of the bike.
     
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  6. Tim O

    Tim O Active Member

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    Alrighty, next issue....
    Noise has been building for a week or two and now I'm hearing a god awful kind of sheet metal knocking. I'd like to say rattle but it's louder than that.

    Almost goes away at high speed, 5th gear (I ran 80 mph on the way home just to check), and is worse accelerating and decelerating. Sounds like it's coming from the collector. Heat shields on sides seem intact and solid.

    My question is; would collector baffles rattling around get pretty loud? It's now where there's no way I'm riding until it's fixed...
    Other info is, no added vibration that I can tell, no loss of power, no other irregular running... although there was a morning a week ago where I thought I felt a little hesitation on acceleration, and I was about to check valve clearances and carb tuning / screens.

    Thanks gang.
     
  7. Colin 85 700

    Colin 85 700 Active Member

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    Can you get the bike to make the noise when sitting, so you can pinpoint it? Or only when driving?
    Knock on the heat shields (not running or yll burn your knuckles) one at a time and see if any "hum" vibrate or rattle, may help find yr culprit.

    Also i believe there are no baffles in the collector, only the mufflers, give them a rap too.
     
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  8. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Very yes.
     
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  9. Tim O

    Tim O Active Member

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    Well, finally had a few minutes to tear the bike apart today and found two things that I think were my issue(s).

    I took all the headers off and pipe 1 had a streak in the collector gasket that makes me think this was much of the noise issue (leak).
    upload_2019-8-4_21-26-10.png upload_2019-8-4_21-27-50.png

    And... there was a piece of collector screen / baffle had exited into the beginning of the muffler and was blocking it.
    upload_2019-8-4_21-30-59.png
    I can't see or hear anything else loose in the collector so I'm assuming it's OK for now.

    So while I'm waiting for new exhaust gaskets... do folks agree that might be why I thought the collector was making such a racket?

    Thanks
     
  10. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Absolutely!
     
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  11. K1llst4b

    K1llst4b New Member

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    Popping means a rich carb.. if that's the only problem then get the carbs balanced and synced
     
  12. k-moe

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

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    It can also mean lean carb, or exhaust leak. Depends on when it's popping.
     
  13. Tim O

    Tim O Active Member

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    Well, this bike teaches you perseverance, that's for sure.

    Had a chance today to re-assemble the exhaust and test her out. So disappointed that the baffle rattle in the collector is still there and pretty loud as well. Which is SUPER disappointing because I put on a new set of pipes I had been saving that are like new, and with all new exhaust gaskets the bike is so quiet and sounds AWESOME when it's not at a speed where the baffle starts screaming.

    So I guess I am in the market for a new collector, unless someone knows some magic to get the offending piece(s) out...
     
  14. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Sometimes you can shake the offending pieces out, or fish a coat hanger thru them to pull it out or break it off. Be aware that with sections of the baffles missing, the tone of the exhaust may change a bit, but it shoul d not affect performance in any measurable way.
     
  15. Tim O

    Tim O Active Member

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    I was thinking of borrowing a borescope from work so I can see exactly what's going on
     
  16. Tim O

    Tim O Active Member

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    Yup, the bike is running great... it's just the god awful noise...
     
  17. Tim O

    Tim O Active Member

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    I need to stop panicking and looking for parts.

    So this is what's going on with my Seca
    • Loose internal baffle on one side which makes sense as it was the noisier side.
    • External hole where baffle attaches in a weld sandwich at the leading edge.
    Here are a few pics and link to video. What do people think of the proposed fixes?

    Capture1.JPG Capture.JPG

    And after cruising the internet for a while, there are some "exhaust sealers" out there? Anyone ever had luck with them?
     
    Last edited: Aug 27, 2019
  18. Polock

    Polock Well-Known Member

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    grind a hole just through the outer shell and just hit the baffle enough to shine it up for welding then weld that whole mess together
    exhaust sealers = no
     
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  19. Tim O

    Tim O Active Member

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    SO... After a failed sealer attempt (just a little, wanted to see what that stuff hardened into... my conclusion is good for a pinhole to hold you over for a while), I went the welding route.
    All I had was a wire welder with flux core wire, no gas.
    With the rust on the collector, even though I tried to shine it up first, I ended up having to put a few layers on to make sure I sealed up any pin holes due to contamination. And, I did the drill hole / plug weld solution Polock suggested. But because I started welding on the front seam where it was thicker, my setting was too high on the baffle area and I instantly put a big ass hole through the collector wall. My 1/8" drill hole plug weld turned into a three layer 1/2" diameter patch job.

    Good news is the baffle is secure and the bike is nice and quiet. Put 50 miles on her today and she sounds brand new.
     
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  20. Tim O

    Tim O Active Member

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    Aaaand…. on the way to work this morning baffle just started to rattle just a little bit again. :mad::mad::mad::mad::mad:

    Exhaust teardown yet again in the next few weeks. :(
     

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