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Carb Jet Sizes XJ650 with pods and 4 in 1

Discussion in 'XJ Technical Chat' started by Dstrong77, Mar 20, 2017.

  1. Dstrong77

    Dstrong77 Member

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    First off I did read the information overload hour info on this. I have an 81 xj650 maxim. It has pods on it as well as a 4-1 exhaust. Hitachi Carb It was that way when I bought the bike. I ordered a rebuild kit for the carb as I had orgianlly thought I had a stuck float, but actually had a leaking oring on the fuel supply. At this time I had not even heard of this forum so I watched a few youtube videos and went about rebuilding the carb.
    When I removed the jets it had a 110 main and a 41 pilot. My kit came with a 110main and a 40 pilot, I had shifting issues that have recently been resolved so I have had the bike out to test how its going. I have not synced the carbs as I need to fix the oring issue on the fuel supply between 2 of the carbs.
    After realizing the stock rebuild kit came with a differnt size pilot jet I dug for info on here. With the formula for the different types of intake and exhaust set ups I believe who ever added the pods and the exhaust before I bought the bike never jetted it properly. Would you guys agree?

    So if thats so: if my altitude is around 1000 ft. On the main jet I would add +4 for the 4-1 exhaust and plus +4 for the pods I would then have 8 and then I need to subtract 2 which would give me a main jet size of 116 correct?
    And if that's right then my pilot jet would then be increase +1 for every +3 increase of the main. Increasing the main jet 6 would mean that my pilot jet would need increased by 2 so a Pilot jet of 42. Sound right?

    If that is the case then would there be any other advice about what I should do before I put it back together. I already plan on changing the plugs as they are black and sooty.
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    carb jet specs at this link
    http://xjbikes.wikidot.com/carb-specs

    the formula in the info overload is just to point you in the correct direction, a place to start
    the sizes you need will be determined by doing plug chops untill you get it right

    how to tune your carbs
    http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

    you would be better off finding the original air box and save your self a lot of time.
    pods are not designed for CV carbs

    check valve clearences
    engine compression
     
    Last edited: Mar 20, 2017
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  3. Jetfixer

    Jetfixer Well-Known Member

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    ++++^^^^1 Agree with XJ550H ....Pods are not real compatible with CV carbs ...oh you might hear folk claim their bike runs great with pods ...until it rains that is . An engine sucking in water is no real good for longevity . Even if Foam is wrapped around them this is not real answer. The engineers knew what they were doing when they designed the bike. I have a stock airbox, carbs have been to church and my carbs are synched right. I have not had to adjust or mess with the carbs since, with pods you may have to pull carbs change jets , put back on test, repeat pull carbs change jets, test etc etc . Good luck
     
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  4. k-moe

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

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    Pod Filters

    The whole thing is worth reading, but pages 5 and 6 will give you a good overview about the issue, and a possible solution that does not involve messing with re-tuning the action of the slides.
     
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  5. Dstrong77

    Dstrong77 Member

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    Well I learn and learn here. Had I bought the bike stock I would certainly agree that the orginal airbox be kept. To be honest I have no idea what the guhy was thinking when he did all the mods to the bike. It looks cool. Hardtail bobber seat Harley fender. But damn he didnt know what he was doing. I am basically working backwards fixing his mods. First the forward controls, headlight, now I need to re jet the carbs and once thats done try to get this synced. I read through the pods thread as well as the information overload hour. I guess I will need to take a chance with those jet formulas and see what I can come up with. I will report back with what I come up with.
     
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  6. Stumplifter

    Stumplifter Well-Known Member

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    Keep fighting the good fight!
    Challenge yourself to NOT curse as you come upon more items that the previous owner carfunkled up. o_O
     
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  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    Busted Knuckles has an air box if you need one AIRBOX
     
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  8. Dstrong77

    Dstrong77 Member

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    That would be an option if I cant get it running decently with the pods. Sounds like I wont. The brains behind all the mods on this bike have some componets that I assume were somewhere else on the bike (possibly under the seat) now mounted in the airbox area. We can fix that though if necessary. Im picking up some jets soon and gonna see how it shakes out on the manometer. I have since found a guy at a Kawaskai dealership who knows alot about CV carbs and will help me tune. (I hope) If not Ill be back here reading. old pics attached of the airbox area. ill take new ones with the pods off to show the crap in the airbox area.

    I just looked at the pics I uploaded, they aren't clear on whats in there, more to come. Basically the 2 and 3 pods bump up to what I believe is a regulator rectifier. I am unsure if its in in its proper location. Wondering if I convert back to an airbox if it will fit or Ill have to move the regulator.
     

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  9. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    From what I've seen here (and there's some wisdom to it), if you can get the pods pushed back a bit by extending the coupling between the pod and the carbs, you end up with a better airflow into the carbs. Other issues aside, doing that and bumping the main jets(?) were the 2 biggest factors to getting pod filters running right. (disclaimer, no personal experience, just reading posts by others).
     
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  10. XJ550H

    XJ550H Well-Known Member Premium Member

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    your battery would be mounted aside of the air box, also extend that rear fender down in the front
     
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  11. Dstrong77

    Dstrong77 Member

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    I got the carbs rejetted. I have a 116 main and 42 pilot. Carbs are mostly synced. Right now the bike runs better than it ever has. I need to do the valve shims next week.Fix 2 exhaust leaks broken header bolts and then resync. Starting to love this thing again. its real snappy on the throttle. Just in time to ride!
     
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  12. sybe

    sybe Active Member

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    You can make a rain shield for the two outter pods using beer or soup cans. Just need to be creative.

    Depending on the pod fikters you can probably make them removable.

    Also if you buy a laundry garment bag (something breathable and made out of nylon) and keep it with you. On days it rains you can spray it with filter oil and place it over the pods for extra protection.
    Just think outside the (air) box.
    https://www.amazon.com/gp/aw/d/B001...SX236_SY340_QL65&keywords=laundry+garment+bag
     
    Last edited: Apr 6, 2017
  13. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Remember that if you adjust any valve clearances, you'll need to re-synch the engine.
     
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  14. Josh85

    Josh85 New Member

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    Hey dstrong,
    Do you have an update on what worked for your jet sizes?
    I also have an 1981 xj650 with pods and a 4 into 1 (how I got it) and looking at rejetting.
    Would love to hear your results
     
  15. Josh85

    Josh85 New Member

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  16. Josh85

    Josh85 New Member

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    Hi dstrong,
    I have the same setup 4 into 1 and pods on an 81 xj650.
    Just ordering jets and would love to know how your setup turned out?
    Cheers
     

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