Overheating,,, HELP (please)
 

I've been on an '86 DR 650 out here in Tanzania for the past year and all was great until recently. The engine feels much hotter then usual which I assume led to a long list of problem...

I flushed the entire oil cooling system, put new oil, filters, even replaced a slipping clutch, put on new gaskets, put in a new batterie, had the piston rings checked (no problem)...

The starter has some issues that were fixed but now the symtoms. Tough starts in the morning (not too cold here but humid right now). Then if I run it for about 10 minutes hard and shut it down, starting it is very tough if possible at all. It turns over well enough but gives a cough, not a backfire but a hallow cough.

My guess, that something is causing the ingine to overheat, this is messing with the starter.... oh which leads me to another problem, the overflow on the carburator leaks when the bike heats up so I have to shut the gas tank off too. Oh boy, are we having fun yet?

I'm sold that it is an overheating problem but have heard ideas like checking the rich/lean setting (not so clear on how to get that right though).

Any ideas? (Drive it off a very tall brigde)

Thanks for your ideas, i'll definitely consider them all....

Poa

What cooling system have you flushed - DR650's are air cooled?

My DR600 is sometimes hard to start when warm, not hot. Solved this by opening the throttle wide several times prior to kickstarting. 600's have a slide carb with pumper, I think 650's have a CV carb, so may not work?

Also check that the valve clearances are correct, quite easy on DR's. When checking them, it'a good idea & opportunity to check & adjust the decompressor cables at the same time (at TDC after the inlet has closed, approx. 1mm of freeplay in the cable(s).

I doubt that overheating would affect the electric start. Is the battery in good condition? If the decomp cables are badly adjusted, the valve may not open, making it harder for the starter to turn the engine?

Are the plugs clean & gapped correctly - my DR600 was sensitive to this & ran .7 to .8mm gaps, not the usual .6 to .7mm gaps.


Steve

Air cooled yes, but they have an oil cooler, which needs occasional flushing.

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Rob Oakley
99 DR650SE
Bathurst, NSW
Australia

I flushed out the air cooler and made sure nothing was blocking the intake/outtake of the oil. My reason... I had a mechanic fix up a small leaking gasket when I was at work and it turned out he used about 1/2 a tube of silicon gasket maker. (slight exageration) but the junk got loose in the engine in small quantities so I opened it up and cleaned everything worried the little silicon flakes were blocking the small veins in the air cooler.

That said. I just finished looking over the basics, plugs, oil filter etc. The plugs had a good (bad!) layer of carbon which tells me that I'm running too rich, correct??? Would this cause the heat? I've had to fix a crack in the intake manifold twice so maybe it is demanding more air with the gas.

Keep the advice coming... I have time on my hands and will look into all the ideas ya'll have. Thanks.

Poa

It's the colour of the carbon build up thats important, not the quantity, which just shows that they need cleaning.

You should be aiming for a light chocolate brown colour. Much darker & you're either running rich or burning oil. Much lighter & you're either running weak or the ignition timing is out. I doubt if the timing has changed as it's generally fixed.

If you had lumps of gasket in the oil cooler pipes, one concern I'd have is that the cooled oil is fed in to the engine case, through the filter & them pumped straight through the right hand side of the crank to the big end. One or two small lumps may not matter but I know of at least one engine that needed a con-rod kit (2 stroke) because of gasket blocking the big end & causing a lack of lubrication.

Steve

Steve

Ummm.. have I missed something but has anyone mentioned the air filter? I know it's a basic thing and it may have already been checked, but if the sir filter is clogged it can cause all of the above, other than the carb leaks. If you have been riding in extremely fine dust, even a blow out with a compressor can't blow out all the crap.

Regards

Nigel in NZ

--"How can I be lost if I don't care where I am?"--