Xr600 & xr650l aussie owners

Discussion in 'Australia' started by Kenno, May 30, 2013.

  1. xrxtz

    xrxtz Been here awhile

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    "I don't think there'd be any downside to bigger fins on an XR, ..."


    Except a big tank wont fit with bin fins on the head. As far as I recall reading.
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  2. Ron50

    Ron50 Long timer

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    And some people don't like big heads on principle. Come in, Spinner. Welcome back.
  3. greyrider1

    greyrider1 old tinkerer Supporter

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    So to maximise cooling you would have to go with both and the basic question is what's the efficency of one over the other....
  4. Ron50

    Ron50 Long timer

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    Looks like you've got another project, greyrider1.

    I'm thinking the oil cooler is a lot cheaper and easier but I've managed all these years without either.

    There's also the question of whether it is necessary or desirable in normal riding to maximise cooling. Too cool an engine wears faster.

    Getting back to your earlier query about radiation and conduction, the sort of temperatures involved with engines is so far short of red heat that I don't think radiation would be a big factor with an XR as the graph of radiant heat loss with temperature is far from linear.

    When you put your hand near a hot XR engine when stationary you have to be very close before it feels really hot from the radiant heat but if you put your hand behind the engine while riding the hot air that has been in contact with the fins is very noticeable.
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  5. greyrider1

    greyrider1 old tinkerer Supporter

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    Some info on oil flow in hydraulics and a marked up flow chart showing the velocity in the stock suction pipe.
    The lower viscosity of hot engine oil probably makes it all work but still can't hurt to upsize the pipe.

    nomographic chart - oil flow in suction pipe.jpg
  6. greyrider1

    greyrider1 old tinkerer Supporter

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    I'm pretty happy with the cooler, normal riding the oil hardly reaches 100*C in the frame.

    I'm just not convinced the flow circuit is the best it could be.
  7. Ron50

    Ron50 Long timer

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    No argument from me on that.

    Somebody else was concerned about the robbing Peter to pay Paul aspect of diverting more oil away from the bottom end but I don't know enough about it to make a useful contribution.
  8. GodSilla

    GodSilla I did that.

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    My '95 does the same. I can't check the oil accurately unless the bike has been revved up a lot while stationary or ridden. At least I don't have to "burp" the oil circuit, jeez I hate that.

    I like those big fin heads, they look really cool. It's a shame they aren't cheaper.

    Ron, the oil cooler on mine doesn't seem to impact running in winter. It does make a noticeable difference in summer though. The extra 4-500ml or so of oil doesn't go astray either.
  9. Ron50

    Ron50 Long timer

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    You've seen this haven't you, Tom?
    http://forum.nx250.de/viewtopic.php?t=160
    It shows the change from the 95 to 96 model oil pumps without the seals, which I believe was to overcome the priming problem.

    When I gave CMC the VIN for my 96 I had told them it was a 95 in accordance with the December 95 manufacture plate but was told it was a 96 year model. My 92 used to drain the oil into the sump if left standing yet the 96 and 98, which don't have the seals in the oil pump, can be left for long periods without the oil tank level dropping. Maybe Honda compensated with a better drain back valve somewhere else.
  10. lookfar

    lookfar from the land of OZ Supporter

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    "burp" the oil circuit?? Haven't heard that one, care to enlighten me?
  11. GodSilla

    GodSilla I did that.

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    Mine is nominally a late '95, but could well be a '96 in HondaLand.

    That's an interesting link too Ron, thanks for that.

    The "burp" is for KTM LC4 625 motors with oil-in-frame. After filling all the orifices with the correct amount of fossils the motor has to be run while a screw is undone high up on the frame oil tank, and when it squirts oil the system is considered bled.
    I've had Yamaha singles that needed "burping" from the top of the oil filter housing too. It creates a right mess if you don't know what to expect, but a strategically placed rag catches most of the squirt. The Yamahas used to squirt directly onto the exhaust pipe - real smart.
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  12. Ron50

    Ron50 Long timer

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    I remember that from my TT500s.

    My BMW 535iS has a similar arrangement for the coolant with a little bolt on top of the thermostat housing to remove after draining the coolant.
  13. cobrin

    cobrin Live to Ride - Ride to Live

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    I reckon I'd leave the flow alone, how good is this and timely for such a discussion:

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  14. GSXR

    GSXR Trail Rider

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    Fascinating. Can we do a see-thru big end window just to ease the anxiety?
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  15. Ron50

    Ron50 Long timer

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    You're terrible, Muriel!
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  16. Ron50

    Ron50 Long timer

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    I checked some temps on the 98 using an infra-red gun and FWIW these were some readings:
    Head fins 148C
    Exhaust pipes about 400C
    Front frame down tube/oil tank 58C
    Engine side covers 60C
    Oil when dropped into a pan for a change 80C.
    Air 22C.
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  17. troy safari carpente

    troy safari carpente Team f5oolery

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    [​IMG]

    found this... one of the bloke's that created the legend, that the XR6 was a nimble little trailbike... :D
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  18. benno.h

    benno.h cageracer

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    Radiation is the only way heat can escape from your engine.

    There's only three mechanisms for heat transfer - radiation, convection and conduction.

    Heat *can* be conducted into the oil, but then when it reaches the oil cooler it was to be radiated out into the environment - cars have radiators after all.

    Most heat is radiated from the cylinder head fins into surrounding air, which then moves away (this is convection, but it has to be radiated into the air first).

    So the big fin head - heaps more surface area for radiation, but whether there's enough air flow in the now much deeper fins to carry that heat away, I'm not sure.

    In any event, I have a both big fin head and an external oil cooler made by an inmate on this forum GSmark. It bolts to the left engine case. It's very effective and adds a bit more oil volume which I think is beneficial as well. I can't remember the exact drop in oil temps (measured in the tank) but it was huge. I was actually worried that in winter, on longish highway runs it was getting a bit cold. I was intending to make a removable screen for the front of the cooler before the bike got stolen.

    BTW GSmark is a bloody awesome guy to deal with. I bought one of his first coolers and after a few years he refined the design a bit - I emailed him and asked him to buy just the updated mount and he sent it out and wouldn't let me pay for it. Top bloke.
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  19. XRHondafan

    XRHondafan Long timer

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    IIRC the whole basis for the finned heads originated from the rs600 factory flat tracker. I believe Honda made factory big fin heads. The aftermarket responded with a weld on option.
  20. XRHondafan

    XRHondafan Long timer

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    I looked at his cooler but was concerned about it getting caked in mud and rocks smashed into it?