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Gas smell in oil

Discussion in 'XJ Technical Chat' started by Glen F., May 4, 2021.

  1. Glen F.

    Glen F. Active Member

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    Went for ride tonight. Felt great!!! I did notice again that after the bike gets really warmed up, the rpms climb. I had the bike idling at about 1200, and it climbed to 2000. Any idea why that would happen? I know it's not dialed in exactly yet, but that shouldn't be happening.
     
  2. Mechanic1978

    Mechanic1978 Active Member

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    vacume leak, or sucking fuel. so we are not solved on this one...
     
  3. Glen F.

    Glen F. Active Member

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    Crap. I have new throttle shaft seals on order, but they won't be here for 2 weeks. I did notice that when I apply the front brake at a stop light, the rpms come down a bit.
     
  4. Mechanic1978

    Mechanic1978 Active Member

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    watch this for a better understanding of why the shaft seals are crucial. watch all descriptions carefully, and pause the video if need be. speciffically watch the throttle fly shaft area and where the mixtures enter from.



    hats off to these guys for the demonstration....
     
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  5. Glen F.

    Glen F. Active Member

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    So for now, I guess I just deal with the idle increase and wait for the throttle shaft seals to arrive, and see what happens after I install them.
     
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  6. Mechanic1978

    Mechanic1978 Active Member

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    correct sir... in the meantime, double check that petcock valve is still dry lol:)
     
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  7. Glen F.

    Glen F. Active Member

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    Just got back in from checking the oil level. All good, but I'll check again tomorrow.
     
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  8. Minimutly

    Minimutly Well-Known Member

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    Well they nearly got that right. On mikunis and hitachis the idle mixture screw adjusts fuel and air together (emulsified fuel) - allong with the butterfly position of course. They also missed the very important progression circuit. Also they have the vacuum signal to the top of the diaphragm coming from the inlet manifold - this would be a disaster, for obvious reasons. A really good illustration though - how do you produce such things?
    @Glen F. - if you're rpm's rise when the engine gets hotter you may have the idle mixture set a tad weak, so that at cold or not so hot temps the engine is underfuelled. The poor old carb has to battle its own shortcomings as well as oil temps changing, reducing friction, clearances opening up etc.. Try a quarter turn open on each screw, then adjust idle speed down when hot. I'm not saying you don't need throttle shaft seals, but I would try this first..
     
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  9. Franz

    Franz Well-Known Member

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    I had the same problem on a car it was a split hose on the PCV valve. High vacuum occurs at idle in the inlet manifold which was sucking in unmetered air via the split hose. This resulted in the injectors supplying more fuel. Revs would increase without me pressing the accelerator pedal. Our bikes don't have fuel injection but vacuum leaks supply additional air. Throttle shaft seals next.
     
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  10. Glen F.

    Glen F. Active Member

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    Oil level stayed the same over night! One less thing to worry about.
     
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  11. Glen F.

    Glen F. Active Member

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    I'll give that a try. I was using a color tune, but it's really hard to see.
     
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  12. Minimutly

    Minimutly Well-Known Member

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    Apples and oranges there, so that argument is moot. A lot easier to adjust idle fuelling than changing throttle shaft seals. Oops, forgot, this is the self flaggelation forum.
     
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  13. Mechanic1978

    Mechanic1978 Active Member

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    this video is just a representation of the understanding of how a CV carb functions, its on a HD carb, so of course it will not have the exact same locations of the circuits, however the visual understanding is there, and Im sure @Glen F. got the picture and now better understands how his carb setup will function. I assumed anyone that seen this would understand that its not thier exact carb setup.
     
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  14. Mechanic1978

    Mechanic1978 Active Member

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    If you had an "unmetered" air flow into the engine in any area, then the PCM and MAF will not register it, therefore it will not be getting any extra fule. it will run leaner, and have a loping idle. if its a large enough leak, it may not idle at all.
     
  15. Mechanic1978

    Mechanic1978 Active Member

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    Thats exellent Glen!!! progress, one problem at a time!:)
     
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  16. Franz

    Franz Well-Known Member

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    You can tell l am not a mechanic :D
     
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  17. Glen F.

    Glen F. Active Member

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    Me neither!!! That's why I'm here for all the expert advice. Sometimes they talk way to advanced for me. Especially when they start with the PCM and MAF. Just guessing, max air flow?
     
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  18. Mechanic1978

    Mechanic1978 Active Member

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    lol... close.... mass air flow. pcm = Powertrain control module ecm = engine control module, but these days the PCM and ECM are one in the same. todays modern cars can have up to 70 different controllers... ughhh!
     
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  19. Franz

    Franz Well-Known Member

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    Mass air flow sensor and power train control module. I save a lot of money doing my own repairs and enjoy working on cars and motorcycles. Lots of knowledgeable people on here and that's great we can keep learning more.
     
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  20. Mechanic1978

    Mechanic1978 Active Member

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    I have been on several forums, and most professionals are timid/cold when another person joins and starts spreading info that they would usually be giving. I left them, as the members were asses, and started a lot of nonsense ranting. it seems realy cool and calm here, and for the most part wrather pleasent and well recieved. So if none of the modders and senior members are not offended, I will continue to inform and assist in any way I can. I'm a 3rd generation mechanic, with a lifetime of knowledge and hands on expierence and Im willing to help whoever I can.. so ask away Glen..:)
     
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