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Haynes manual is wrong for valve clearances?

Discussion in 'XJ Technical Chat' started by yamaman, Aug 6, 2011.

  1. yamaman

    yamaman Member

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    wait a minute, I just spent 1.5 hrs doing this crap and Now I remember something about the clearances being wrong? My manual says for the '82 650 Seca Non YICS both intake and exhaust are .16 - .20mm

    can someone please clarify? Thanks
     
  2. day7a1

    day7a1 Member

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  3. day7a1

    day7a1 Member

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    The Haynes manual is almost certainly wrong, but I can't say what is right. It gives two different sets of numbers for the 650J and RJ.

    Do you still have your side cover? It says the correct version on mine.
     
  4. yamaman

    yamaman Member

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    Hm ok thanks, let me check. I can't imagine things going wrong if you set them all to .16 - .20 can you?

    I can understand a Typo, but to go out of your way to specifically type another line that says the RJ Seca has different values is kind of a big deal
     
  5. day7a1

    day7a1 Member

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    In the haynes manual the RJ has a very different cam profile, the lobe height is .3 mm smaller on the intake cam only.

    Did you replace any shims?
     
  6. yamaman

    yamaman Member

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    yeah well I just put my original RJ cam in a used 650 head which I also resurfaced the valve seats (lapped) so I was expecting big differences. I used the buckets and shims that came with the used head, and I had 16 spare shims from over the yeas. 2 were good, 6 were out, I was able to get 4 in, so I have to order 2 shims.

    what you just found about the .3mm lobe height difference is EXACTLY what everyone needs to know!!!!!!!!!!!!
     
  7. day7a1

    day7a1 Member

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    Your intake valves will open a little later and close a little sooner, causing a richer mixture and less power.

    If it's 1.5 hours and ~$30 worth of richer mixture and less power, you'll just have to see, I guess.

    From my understanding it started from a "copy and paste" error in the RJ supplement....leading to a whole separate line in Haynes. But I wasn't there.
     
  8. yamaman

    yamaman Member

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    so you think I could compensate and get the extra power they took out? lol. sorry didn't follow you precisely
     
  9. day7a1

    day7a1 Member

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    If you look in your Haynes manual, pg 32, there is a whole separate chart for the RJ, though THE TYPO SAYS J AND (UK).

    More than just a line item, I don't know why there would be a whole other CHART for a wrong value.
     
  10. day7a1

    day7a1 Member

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    No, they didn't take out power by changing the valve clearance, they added power by changing the cam profile and had to change the valve clearance as a result of that.

    If this clearly typo and mistake driven list of number is to be believed, that is.
     
  11. yamaman

    yamaman Member

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    so the chart is for the RJ, which must be real cause it was created, the J above the chart is a typo, and in fact the RJ has different values. This is actually convincing stuff, Real reasons to guide an eduacated decision, as opposed to what others think. Well untill somone proves me otherwise I'm leaving them 16 - 20 across the board. Thanks a million day7
     
  12. day7a1

    day7a1 Member

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    Well....I'm not convinced either way, I'm just providing info.

    I hope you're right, just check your plugs a lot the first few hundred miles.
     
  13. biggs500

    biggs500 Active Member

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  14. yamaman

    yamaman Member

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    tried pasting the link above, no luck, I think I don't have permission cause I'm not your friend. What's it say?
     
  15. biggs500

    biggs500 Active Member

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    Sorry about that. I was having a few difficulties uploading the picture.
     
  16. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Okay, here's the deal:

    According to factory service manuals and parts books, we have:

    Intake camshafts:

    Source: 1980 XJ650 Euro (4K0) service manual
    Application: 1980-81 XJ650 Euro engines (4K0 and 4K1 models, non-YICS)
    Part number: 4K0-12171-00-00*
    A (total height = B "base diameter" + C "lobe height") = 36.80mm
    B (base diameter) = 28.0mm
    C (lobe height) = 8.80mm
    Clearance: .16 - .20mm

    *Note that this camshaft is the same as the camshaft used on XJ700 air-cooled models and all XJ750 air-cooled models, and the clearances for these models in all service manuals is listed as .11 - .15mm.

    NOTE: this information about lobe height is probably correct; the clearances listed (.16 - .20mm) may not be.



    Source: 1980 XJ650 Maxim (4H7) service manual
    Application: 1980 XJ650 North American engines (4H7 models, non-YICS)
    Part number: 4H7-12171-00-00
    A (total height = B "base diameter" + C "lobe height") = 36.80mm*
    B (base diameter) = 28.0mm
    C (lobe height) = 8.50mm
    Clearance: .11 - .15mm

    *Note that 28.0 + 8.50 = 36.50mm, NOT 36.80mm

    NOTE: this information about total height ("A") is probably incorrect.



    Source: 1982 XJ650RJ North American (5V2) service manual supplement
    Application: 1982 XJ650RJ Seca engines (5V2models, non-YICS)
    Part number: 4H7-12171-00-00
    A (total height = B "base diameter" + C "lobe height") = 36.50mm
    B (base diameter) = 28.0mm
    C (lobe height) = 8.50mm
    Clearance: .16 - .20mm

    NOTE: this information about lobe height is probably correct; the clearances listed (.16 - .20mm) may not be.



    Source: 1982 XJ650RJC Seca Canadian (15U) service manual supplement
    Application: 1982 XJ650RJC Seca engines (15U models, YICS)
    Part number: 4H7-12171-00-00
    A (total height = B "base diameter" + C "lobe height") = 36.50mm
    B (base diameter) = 28.0mm
    C (lobe height) = 8.50mm
    Clearance: .11 - .16mm

    NOTE: this information about lobe height and the clearances (.11 - .15mm) are probably correct.




    Summary:

    It appears that there may have been a copying error(s) in the factory manuals, which was then repeated in Haynes (remember, Haynes was a British company at the time their XJ650/750 manual was published, and were probably using Euro model manuals as their "baseline" guides, and this is where the "valve clearance issue" starts......

    A) the 1980 North American (4H7) service manual has an addition error in the total cam lobe height dimension ("A") of 36.80mm, rather than the correct 36.50mm height. This is probably a copying error from the Euro (4K0) service manual, which (correctly) lists the lift at 8.80mm, and the total lobe height as 36.80mm.

    B) my best guess is that the intake clearance listed in the 1980 XJ650 Euro (4K0) manual and then copied into the 1982 XJ650RJ supplement manual (and then into Haynes) is incorrect............it is listed as .16 - .20mm, but is really supposed to be .11 - .15mm. Note that this same camshaft (4K0-12171-00-00) was also used in USA XJ700 air-cooled and worldwide in all XJ750 air-cooled engines, and in all those instances, the valve clearance is listed as .11 - .15mm.

    IT IS DOUBTFUL THAT YAMAHA ENGINEERS WOULD SPECIFY DIFFERENT CLEARANCES AS A "TUNING" METHOD, as valve clearances are typically related to physical characteristics and wear/maintenance considerations, and are thus a property of the metals used, thermodynamics, and other engine characteristics (piston head-to-valve clearances, etc.), rather than for "engine tuning" reasons.

    C) note that the North American XJ650RJ Seca tune-up specs tag lists the intake clearance as .11 - .15mm.

    D) It would be VERY USEFUL if an XJ650 Euro 4K0 or 4K1 model owner could confirm what their tune-up specs labels says for the intake clearance......my bet is that these sticks would show the correct clearance spec of .11 - .15mm.

    E) For those who are curious, the 1980-81 XJ650 Euro (4K0 and 4K1 models) used the 4K0-12181-00-00 exhaust camshaft, same as the worldwide 1981-84 XJ750 engines (excepts 750RL), while the North American model XJ650, XJ650RJ, and XJ650RJC models all used the 4H7-12181-00-00 exhaust camshaft.
     
  17. day7a1

    day7a1 Member

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    That's all fine and dandy, but on further consideration...

    of COURSE the intakes are .11-.15 and the exhausts are .16-.20..

    The exhausts need more room to expand than the intakes...

    doh!!

    Just like any production engine.
     
  18. bigfitz52

    bigfitz52 Well-Known Member

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    Precisely.

    .11~.15mm intake, .16~.20mm exhaust is the correct spec. Yamaha simply listed the exhaust spec for both intake and exhaust and it got picked up by Haynes. I have a "650 Seca" book; it's wrong in the RJ supplement but correct in the 'base' book.

    There are quite a few errors like that in the factory books; where a line simply gets repeated or the flat wrong spec inserted. In one of my 550 books it says the 550 Maxim has an 18" rear wheel. (It's a 16")
     
  19. yamaman

    yamaman Member

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    ok I corrected my clearances, thanks guys. waitin on 2 shims...
     

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