Hi all,

I've just pulled my 83 XT600 apart after having the nut on the end of the crankshaft chew through the seal and some of the crankcase (RHS clutch cover) and very predictably found all, I hope, of the bits in the oil pickup strainer.
I've blown air through the oil lines except for the crankshaft and all seems ok. After cleaning and reasembling the engine and reparing the crankcase cover the engine started with a lot of effort but is running well. Piston/ rings, barrel bearings all seem ok too.
The difference now is that its very hot and very hard to start from cold. The oil tank never even got warm before and is now hot to touch after 15min riding, the crankcase is very hot (can put my hand on it but not for long). oil is flowing back to the tank and after taking it apart again I've found plenty of clean oil in the rocker cover, and everywwhere else. I also found the piston with a film of oil over it. Just wondering how hot it can/should get and if I need to be thinking about getting the crankshaft looked at?
I was thinking rings/ valve guides or something similar but can't figure out the heat.
I have an oil cooler but not a temp guage so sorry for the vagueness.
I've read that the dipstick can get hot enough to melt but I'm reluctant to ride it at all as it never even got warm in the past.
Sorry for the rambling post, am quite stuck.

Cheers.

Chopper,

Have you had the spark plug out to check its colour? The bike might be running weak causing overheating. Incorrect ignition timing can also cause a hot running engine. I would check over these first.

Cheers Sam.

That oil tank and crankcase are hot to the touch / cannot be touched more than a few seconds is quite normal in hot weather. The difficult starting can be explained by wrong idle jet setting - see other posts, or an air leak between carb and cilinder head.
This for the easy items, the last post suggested wrong timing also.

Certainly, the 'hotness' is not explained by a blocked oil passage in the crankshaft, which I would not expect when your piston was well lubricated when taken out.

Auke

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Auke
http://aukemarieke.blogspot.com

Thanks for the response guys,
The barrel is still off and was most worried about the crankshaft but it seems not to be an immediate problem. So, very happily I'll leave that alone for now.
The flywheel has three timing marks and has always been aligned with the first one, the circle with a line through it, like a plimsol line. the second is an I H (or similar) the third is |I (i think). adjusted at the first its always been very easy to start cold and much less so hot. The mix is rich and something I need to do something about.. there is carbon on the piston crown and head, and on the plug too when I took it out.
Had the bike been this hot initially it would have made sense to me, its just the sudden change from a cold oil tank to hot without changing much that worried me.
This has been rebuilt about a year ago due to a sudden stop on a freeway when the oil pump failed and the piston welded itself to the cylinder. This included an oil pump, rebore/ rings/ bearings.....
Sooo... I'll put it back together again and play with the mixture. The timing I'll set to where it was for the moment. any advice on that one would be great. Sounds like it is ridable though while I sort this out though.
Trouble is, its running really well once its going..... just hot... but maybe fiinally working correctly and in need of proper adjustment (trying to be optimistic).

Thanks again.

You cannot chnage anything on the ignition timing, apart from changing the CDI etc.

However valve timing should be correct. You say you put it aligned with the first mark, I interpret that as the first one 'reading' from left to right looking at the left side of the bike.
This is definitely wrong; this is the mark for high-engine-speed ignition timing. The three marks you mention are as follows (reading from left to right):
1 - high-engine-speed ignition timing mark
2 - idle ignition timing mark
3 - Top dead center

To verify this last one on your bike, turn the engine (counterclockwise seen from the left of the bike) till all valves are closed. Insert screwdriver into plug hole, feel out the top dead center. The timing mark that then coincides with the mark on the casing is the one you need to time the camshaft / valves.

Auke

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Auke
http://aukemarieke.blogspot.com

the three marks were reading left to right as you said, and was set to the one on the far left ( high engine speed ignition). checking TDC is something I should have done long ago.. Strange that it's been set to that for a very long time.... I'll put the barrel and head together this evening and have a look..
thanks for the help!

Just in case you need them, I have recently updated the XT600 Manuals for download -> Download Manuals

Also the is a good article on spark plugs and diagnostics -> Spark Plugs

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well....
The timing is now set to the first mark, valves adjusted, everything cleaned out again, and put back together, it seems fine.
Started first kick, running well. After 15 minutes of riding the oiltank is warm but not hot, the crankcase is quite warm on the RHS and hot on the left. There is also a huge increase in power, leaving me on the rear wheel a few times. . Started easily hot too, which is not something it has ever done. So, I'm inclined towards optimism until proven otherwise!
Thank you all for the help.

Great to hear....................enjoy!