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how hot is hot??

Discussion in 'Technical and Troubleshooting Torque' started by dr650, Nov 19, 2004.

  1. Hi guys...quick question . How hot is hot when it comes to engine temp??My dr 650 seems to heat up real quick.When i got home tonight i had the bike on the side stand whilst i opened the garage, and i noted that the oil that i coul see thru the little window was actually boiling!.Is this normal ?.The engine just seems very hot.I undersatnd that riding in traffic will heat the engine more than say on the freeway ,im just not sure if this is ok...newbie with very limited knowledge of bike mechanics..any help appreciated..

  2. Either your engine is faulty, your oil needs replacing, or both. Oil should not boil, in just about any engine. If it boils it usually means that it's diluted with some sort of contaminant (water, etc.) or you have the wrong type/viscosity of oil for the engine. Suggest you attend to it pronto. If you leave it too long, you'll probably blow a head gasket, or worse.

    I would change the oil immediately, and keep a careful eye on it for a few weeks. If you see it boiling again, immediately drain the oil and check it. If it's contaminated, then you have an engine problem. If the oil is fine, and being that the DR's is air cooled, I would think that something is wrong with the engine. You don't have any plastics or OEM items that would be blocking or obstructing the air flow to the engine?
  3. Boiling oil generally means that the oil is way past its use-by-date and it has broken down.
    It would be offerring next to no protection.

    Do as Jason suggested, dump the oil and start again.
  4. Oil temp max, and this is oil dependant, too, is around 70-90 degs, before it starts to fail. And no, it won't "boil". If it did, it'd be releasing gases that could cause significant pressure excursions within the engine's confines, if ignited.

    I'm tipping that it was merely the oil circulating within the engine, thus giving it that "bubbly" look.

    From what I remember from my motor mech days (yeah, guys, back when they used parafin oil...) oil would hit a critical temp, lose all viscosity, break down and fail as a lubricant. Engine damage was sure to follow.

    Also, engines that have plain bearings, such as crankshaft bearings, will quickly wipe themselves when they get too hot. The white metal, as it's called, relies heavily on oil that can withstand high temps without failing. Roller bearings are a bit more forgiving. They're also noiser, and have lower tolerances.

    Where I work now, most of the oils are about $30 a litre or more. They operate in highly critical enviroments and oil temps are usually regulated to around 70 degs, max. In some applications, 45 degs is normal operating temp.

    If there's water in the oil, the oil will turn a greyish milky color, as the water and oil emulsify. When that happens, start it up, get it hot, drain it, change filter. See how it goes. Might have to be repeated. To boil off any water, you're looking at getting the oil up to 100 degs. And that's fairly high.

    I've just done a quick search for info on oil temp limits for bike and car usage. I couldn't really find much info, but then I've not done a detailed search. Closest I've found is a forum for aviation use, where 180 degs F is quoted as normal op temp for some aviation engine oils.

    See what your mechanic reckons. He'll probably use it as a reason to get your bike serviced........

  5. Thanks for the advise will get it checked by mechanic...there is definetly something wrong as even the engine bottom casing was really hot .I dropped a little water on it and it dried nearly instantly and was still hot to touch some 2 hours later..
  6. 2 hours later?!?!?!?!?!??!?!?!?!?!?!?!

  7. hi dr650

    is your bike air or water cooled ?

    i remember on aus.moto a about 9 months ago,
    somebody posting a website of a bloke acid
    testing a 600 ZZR or something like that. he
    ran a series of tests to see how undestructable
    this bike was-- ie ran it flat tac for 24 hours...
    then removed most of oil and ran it for a further
    24 hours flat tac.

    the report dropped my jaw.

  8. my oil temp gets up to 100 degrees occasionally after lots of slow traffic on a hot day... cooling fan kicks in around there
  9. Lucky both of you my only temp guage is the one inside my jacket!
  10. I second that! Note to anyone reading this, DON'T try this at home. I recall at the Moto Freestyle meet at Calder they tried blowing up this Ninja but ran out of juice before it could die, would be an awesome testimony for a Kawasaki engine I reckon.

    Talked to the blokes at Vic Bike Wreckers, they reckon it started the next day no dramas.
  11. Sounds to me like a head gasket..pumping exhaust gases into the oil jacket would heat things up real quick.

    Usually this is accompanied by a lot of smoke when backing off the engine - riding the engine into stops etc...is this evident? Whats oil usage like?