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XJ600 Cafe Racer project

Discussion in 'XJ Modifications' started by GoCrazy, Sep 13, 2016.

  1. Captn_Obvious

    Captn_Obvious New Member

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    Did you check to make sure the stock jets are in there? The previous owner might have changed them.
    As you mentioned, check the floats. Also, set the fuel level/float height. My bike was running way too rich cause the the float bowls were overflowing. Once I set the proper float height it went lean, which is what I expected as I'm running pods (yes I'm running pods and I'm perfectly happy with them :D ). After that it was a matter of putting in the proper jets to get it to run properly.


    BTW, do you live in the Tricity area by any chance?
     
  2. GoCrazy

    GoCrazy Member

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    Yes, the stock jets are there. I've checked the needle valves and it turns out that #3 and #4 are worn and they leak. I wanted to put pods as well, but my friend adwised me agaainst that. He switched to pods on his xj600 and it was a bad idea. On his second project with Xj600 he made a custom airbox -like pods setup and that actually worked.
    I live in Warsaw, thats around 350km to Tricity.
     
  3. GoCrazy

    GoCrazy Member

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    So I replaced my needle valves and wanted to set the float height. First I checked it with ruler - #1, #2, #3 were 22 mm, #4 23,5 mm. I set all to 22 mm. Since the manual says XJ600 floats should be 16,5-18,5 mm and I could not find what is the reference point for this height, I decided to check the fuel level with a rubber hose. After hour of looking for something that would work as an adaptor for the hose-bowl nipple, I finally checked the fuel level :
    #1 - ~3mm below the bowl - carb mating surface
    #2 - 4mm above the line,
    #3 - 6mm above the line,
    #4 could not unscrew the bolt, but it was clearly above the line as fuel leaked out of the carb

    I don't know what to make of this - if the float height is higher than the specified height, there should be less fuel in a bowl and engine should run lean. Instead, there's too much fuel.
    Could it be that I measured the float height wrong? Or valve seats need replacing?
     
  4. Captn_Obvious

    Captn_Obvious New Member

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    If there's too much fuel, try adjusting the tabs on your floats so that the valve is closed sooner (with less fuel in the bowl). There's a great PDF on xj4ever on setting the floats: http://www.xj4ever.com/setting fuel levels.pdf

    Try playing around with the floats. If you're still getting too much gasoline then it could be the valves leaking.
     
  5. GoCrazy

    GoCrazy Member

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    I've been playing with those tabs all afternoon and managed to set the right level on carbs #1 and #3. On the remainin two I can't bend it the right amount, it's either too much or not enough. Is there any trick for bending the tab?
     
  6. desmotom

    desmotom Active Member

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    Make sure the floats aren't upside down. I'm guilty of that :(
     
  7. GoCrazy

    GoCrazy Member

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    After few hours of bending the tabs up and down 3 carbs are set, one more to go :)
     
  8. Captn_Obvious

    Captn_Obvious New Member

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    Good point, been there done that :)

    From what I noticed, even slight bends can have a significant impact on the fuel level in the bowl. Can be frustrating, but you gotta be patient :)
     
  9. GoCrazy

    GoCrazy Member

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    I've used electronic callipers the take measurments. Every 0,05 mm counts. Maybe it's due to the age of my bike, but for each carb there was a different height. I tried to set them according to the manual - no luck, I checked with the rubber hose method and each fuel level was different. After some time, I measured how much each tang protrudes above the flat surface of the float assembly. For one carb it's 1,65mm - this gives me the exact level of fuel in the carb. I tried exactly the same 1,65mm on another carb and the result was slightly different. Is it possible that each float has a slightly different displacement after 26 years of use ?
     
  10. GoCrazy

    GoCrazy Member

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    So I 've been having this issue lately - the bike doesn't start when cold. I need to use a few sprays of starting agent into the airbox, then it cranks several times before it finally starts. When it warms up, the engine starts like a charm.
    I've checked so far:
    - no air leaks around carbs and air intake
    - pilot screws set
    - carb balance and synch - done
    - new spark plugs
    - float level - set
    - I've checked the ignition coils resistance - it's 2,3 Ohm - according to the manual - 2,8 +/- 5% - can this result in weak spark ?

    Yesterday, I borrowed a compression tester and it showed 100 psi on #1, #2, #4 and 105 psi on #3 cylinder. I performed the test on cold engine. When I sprayed some oil into each cylinder, the compression jumped up to 125- 130 psi. According to the manual, the min should be 142 psi. I was quite surprised at the results as the bike would start with no problems before I took it apart. Then I remembered that I changed oil according to the manual - fully synthetic and the PO must have used a thicker oil, possibly some "engine doctor" as well. As a result my new oil has flushed the carbon deposit making the engine loose compression. Am I right to suspect the low compression as the main culprit behind hard cold start issues? Should I check something else?
     
  11. sybe

    sybe Active Member

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    If your compression is that low, you might want to think about replacing the piston rings and checking the bore sizing and warping. It really not that hard to do. just a lil pricey. The head gasket alone is like 80 - 100 depending where you get it. For all the gaskets + grommets + rings and other various things it will cost around $300-400+. Also while she is apart go and check the valves and clean then.
     
  12. GoCrazy

    GoCrazy Member

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    That's my plan - replace the rings and check the valves. Indeed, prices are in 300 - 400 usd range. I hope the cylinder head is ok.
     
  13. Kickaha

    Kickaha Active Member Premium Member

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    The manual should say that the compression test should be done with the engine warmed up and throttle held wide open so comparing a cold test to the manual specs doesn't give you an accurate indication

    If the bike started fine before you took it apart then chances are it's something you've done, I can't see one oil change making that much difference, I've done that in plenty of bikes and it's made no difference
     
  14. GoCrazy

    GoCrazy Member

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    I did hold the throttle open, engine was cold as I wasn't able to start it. I was told by a Kawasaki tech guy, that compression check performed on cold engine is only slightly lower.

    As for the oil change, switching from mineral or semi-synthetic to synthetic may result in flushing the gunk and carbon deposit.
     
  15. Kickaha

    Kickaha Active Member Premium Member

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    Within one oil change? I doubt it would happen that fast
     
  16. francois maltais

    francois maltais New Member

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    Is your bike an xj650 82 seca by any chance? I could really use the final measurement for the custom triple tree if you have them!!
     
  17. francois maltais

    francois maltais New Member

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    Double post
     
  18. GoCrazy

    GoCrazy Member

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    My bike is XJ600 1990 and I don't have the measurments. They guy who did all the work took all measurments from the original tripple tree clamps.
     
  19. Mshawnm109r

    Mshawnm109r New Member

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    WOW thats awesome!! a cup full of impressed, cup of amazing, a table spoon of jealousy, mix with 2 gallons of inspired...........i love that bike!!!!
     
  20. GoCrazy

    GoCrazy Member

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    Hello guys, much time has passed and not much work done. I had to focus on my house refinishing and other small to-dos around the household.

    Few days ago I resumed working on the bike. I pulled the engine out of the frame and removed the cylinder block + head for measurments. The main reason was to replace the leaking head gasket but I thought that it's a good opportunity to check all the insides and replace what needs replacing.
    What I did so far:
    Pistons measuring and checking for wear - all of them are within specs, and show minimal to no wear.
    Piston rings - so far checked only cylinder #1 - rings #1 and #2 thicknes is according to the manual, ring gap is.
    Ring thickness - both rings as specified in the manual
    Ring gap - according to the manual - standard gap is 0,15mm - o,3mm, max 0,7mm
    #1 ring - 0,35mm
    #2 ring -0,45mm

    I have also notices two scratch like marks inside the cylinder #1. They are not deep, definitely not detectable by touch. It appears to be more like a discoloration. Today I'll check the piston - cylinder clearance.
     

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