Cylinders not firing at same temp??

Discussion in 'Land of the Rising Sun: ADV Bikes from Japan' started by Farway, Jun 21, 2014.

  1. Farway

    Farway Adventurer

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    I wonder if some of you clever people can help. My honda Crosstourer has a VFR1200 (V4) engine in and I notice this the other day. Could it be one of the cylinders are running hotterthan the other??
    Thanks in advance

    Attached Files:

    #1
  2. OldPete

    OldPete Be aware

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    Does is run good ? No rough running or engine miss ?
    What's the mileage ? Have the valve clearances ever been checked ?

    My guess... Just a different batch of tubing on the one side.
    #2
  3. Farway

    Farway Adventurer

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    Runs perfectly fine. 10k miles on, 1st valve clearance check due at 16k...maybe differrent material...
    #3
  4. D.T.

    D.T. Difficult but useful

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    You could get an non contact thermometer and check. Or just after starting put your hand close to the pipes.

    Is there some sort of air injection for emissions?
    #4
  5. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    I suspect the left side is running a little richer than the right side, oriented with your picture.

    You have 2 different temperatures here, there is a Cylinder Head Temperature, and an Exhaust Gas Temperature. When a cylinder runs lean, the CHT rises and when the cylinder runs rich the EGT rises. In virtually all engines with a single point of fuel atomization, whether a single carburetor or a single throttle body injector, the cylinders closest to the fuel source get more gas than the cylinders furthest away. This is the primary reason for multiple fuel injectors and also multiple carburetors. Anyway, since lean running will ultimately damage an engine, and running rich will not, or it could be argued at least not as badly, standard practice has always been to adjust the leanest cylinder for proper mix and if some run rich that's how it goes.

    Anyway, I suspect your bike is running with the right side there at a proper mixture setting and the left side running rich.
    #5
  6. anotherguy

    anotherguy Long timer

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    I highly recommend as long as the bike runs well you ignore such minutia. There are many reasons for the pipes to be different colors and even temperatures. And none of them are worth the effort unless you need a science project. Ride it and forget.
    #6
  7. CycleDoc59

    CycleDoc59 Wrench Rider

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    Pull all the plugs and compare. If one is noticeably
    different, that cylinder has a problem. Lots of things
    it could be; the plug itself, ignition to that cyl, injector
    problem, throttle body balance, valves, vacuum leak/etc...

    You indicated the engine was replaced?..often things, such
    as throttle bodies get bumped in that process.

    All exhaust header pipe temperatures should be fairly close, if
    not, the Chinese would say, "sumtingwong"
    #7
  8. OldPete

    OldPete Be aware

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    Looked at you posts and you're in the wet UK.
    Looked at images of said bike and that pipe is right behind a short front fender.
    So road spray as you ride all weathers... Is salt used on the winter roads ?
    #8
  9. Farway

    Farway Adventurer

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    Hi. I also thought that and no, I have an extenda fenda fitted and tbh, both header pipes are near enough taking the brunt of things. This bike has only seen salty roads maybe 2-3 times and that was several month and several thousand miles ago.
    #9
  10. Farway

    Farway Adventurer

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    Thanks, I need to see the dealers and get them to inspect but I suspected this might be the case. It was mentioned in an earlier post to check header temps...I think this will be a clear indicator!.

    Thanks again.
    #10
  11. yokesman

    yokesman Been here awhile

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    put a line of orange crayon on each tube hear the head ,run it ,see what difference in color you have.
    #11