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New to forum and carb questions

Discussion in 'XJ Technical Chat' started by Loveland'81, Jul 1, 2019.

  1. k-moe

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

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    Were valve clearances checked?
    Cam timing?
     
  2. Loveland'81

    Loveland'81 Member

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    Valve clearance was corrected how do I check valve timing and to adjust?
     
  3. Loveland'81

    Loveland'81 Member

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    Ok all so I went back and polished the slide bores again this time with 1000 grit. It had a positive effect. I still get a sputter at 5k but I can now at least push through it up to red line. It takes a few seconds to get past the sputter however. I still have a slow to return to idle but its better than it was.
     
  4. Loveland'81

    Loveland'81 Member

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    Took bike out on road and max speed is a whopping 65mph. Wide open sputter. I am going to continue my quest to fix this bike. Runs great up to 5500 rpm. One thing I noticed is the carb to head boots. After I shoe goo and liquid taped the boots I ran electircal tape around them just as another seal. I saw the tape moving in one spot in and out on the number 1 and 2 carbs. Seems like air could be pushing on them. Could cracked carb to head boots be causing all these problems? Thanks everyone, this bike is diffrent from anything I have worked on and its been a challenge to say the least.
     
    Last edited: Jul 27, 2019
  5. MaximusXJ650

    MaximusXJ650 Member

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    The bit with the 65mph and sputtering is my current issue. Let me know if you get a solution!
     
  6. k-moe

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

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    You line up the crankshaft to the T mark and check that the dots on the cams near the chain sprockets line up with the marks on the cam caps.
    [​IMG]

    [​IMG]
     
  7. k-moe

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

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    Yes. A vacuum leak will alter the fuel to air ratio, and a leak at a flexable joint will be a variable leak (the size and volume will change as engine speed changes).
     
  8. Polock

    Polock Well-Known Member

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    that 5K stumble can also be from the exhaust system
     
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  9. Loveland'81

    Loveland'81 Member

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    Cam timing looks good. I'm going to check valve clearance again while in in here
     

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  10. Loveland'81

    Loveland'81 Member

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    Valves
    How can I verify if the exhaust is causing this Polock? Currently bike has stock exhaust all the way back. Seems to flow just fine but hard to tell when I am on the bike under load how it is.
     
  11. Loveland'81

    Loveland'81 Member

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    Valve clearances were all in spec
     
  12. Loveland'81

    Loveland'81 Member

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    Ok all here is the latest update. I went through everything wiring realated including the pickup wires and tci wires they all looked good. I decided to check again for vacuum leaks and sprayed everything with starting fluid. I found the idle increased as I sprayed 1 and 2 carb boots to head. I could also see bubbling of the starting fluid after I sprayed it. I am thinking I may have found the issue. I am going to order new boots. Ill post reply once I get them installed.
     
  13. Polock

    Polock Well-Known Member

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    be careful with those carb boot bolts, sometimes the come right out sometimes they twist right off
    if it doesn't feel right, quit
     
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  14. Loveland'81

    Loveland'81 Member

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    Great news everyone! After replacing the carb to head boots and voltage regulator I had the exact same problem. Idle hang and no power past 5500. Out of frustration I went over everything again including the recent carb rebuild parts installed. Drum roll please!... found the main jet needles were wrong! The kit I ordered had y262 needles and I never suspected them to be the fault because it was a kit and new ( not chacals ) Apparently these needles fit 275 engines or smaller, crazy. Anyway I swapped in the originals and low and behold all problems solved! Runs all the way out and wow fast and fun. Back story is I didnt even start or run the bike when I bought it. I went to work right away rebuilding the carbs and getting the bike back in order. For anyone having issues like this check your JET needles, aftermarket companies get it wrong sometimes. Thanks all for helping.
     
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  15. XJ550H

    XJ550H Well-Known Member Premium Member

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    that's not a part changed to often unless you see damage to them. not even in church.
     
  16. Loveland'81

    Loveland'81 Member

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    The only reason I did change them is because they were setup for a 750 and they are 750 needle jets. The kit had all the correct 65o parts except apparently these needles. I assumed they were the y-10's but couldn't see they were y262 until I closely looked at them today. I never suspected. But looking further into it the 262 crosses over to a 10. They may have been inferior to oem but either way I am thrilled. Way to many hours spent figuring this one out.
     
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  17. Chal

    Chal New Member

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    Thanks for putting the time into communicating this one all the way to the fix that finally solved the problem - its what makes a good forum great.
    I've just taken the carbs off my XJ750 AGAIN trying to resolve a similar behaviour - guess where I'm going to look first! Thanks again
     
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  18. a100man

    a100man Well-Known Member

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  19. Loveland'81

    Loveland'81 Member

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    I didn't suspect the needles at all since they came in a new kit. They were supposedly the correct needles and everything else matched the 650 configuration. In the mean time I replaced a bunch of other stuff and while beneficial were not the problem. The needles were the only thing that made since after some serious brainstorming. Didnt even have to pull the carbs. Hats off, needles swapped to the Y-13 and boom ran perfect. I chased this issue for many hours, weeks even because it was driving me crazy. I cannot believe how much this bike pulls. It blows away my cx500.
     
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  20. a100man

    a100man Well-Known Member

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    Carbs are tricky to get right - especially if you're not dealing with a 'standard' set-up, but your description sounded like a classic main jet issue. I had the same when, due to (my)poor reassembly, a main dropped off into the float bowl. Stone dead at 50% throttle. The needle bit was hard detective work I'll admit. Glad it's now sorted.
     
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