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xr350 help needed

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So this is my first post and I've got to say this forum is unbelievable. I picked up an 1983 xr350 last week for $850. The guy said the bike wouldn't run without the choke on and that the valve seals leaked. I wasn't scared because I really think I can fix it. I drained the old fuel and sprayed alittle carb cleaner in the left side carb. The bike ran with out the choke on no problem. Now the problem is the bike blows white smoke alot. It does disapate by half when the engine is warm. It rides fine but the smoking needs to be fixed. What do you think is it the valve seals or piston rings or What?

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Blue smoke at cold startup that disappears when hot = worn valve stem seals. Blue smoke that gets worse as the engine warms up = worn piston rings/piston.

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Replaced the valve seals today no problems. The old ones looked fine i mean they seemed to seal good when I moved the valve in the guides. Piston looked good a little build up on it but it came off. I went to reinstall the cam chain with the sprocket marks horizontal to the head and the piston at tdc. Does anyone know if this is the case for an 83xr. I been following a much newer manual from an xr 400. Could my smoke problem be something else? There is oil residue on the exhaust pipe and platers on my rear fender.

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Check the ring end gap. The rings usually go before the bore or the piston. If it's too loose it will burn oil.

Also take the valves out and check the valve guides. If the guides are too loose it will use oil as well.

You are correct with the cam install. Crank at TDC and lines on cam gear even with the head. I'm not sure about the 350, but this is really a pain on my 600. The chain likes to slip off the bottom sprocket, and it's hard to get it back on. I have found it easier to take the clutch side cover off when I'm messing with the cam chain.

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put it all back together and it started but it still smokes. The valves were adjusted cold .005 for intake and .006 for exhaust. It backfires quite a bit and the auto decompression seems to engage more often than before. I guess I'm going back in to replace the rings.

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auto decompression seems to engage more often than before. .

Are you referring to a cable from the kickstarter to the compression release lever?

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I don't know if this helps,

From My 84 XR350R manual:

Standard valve clearance: (when engine is cold)

In. 0.05 mm (0.002 in.)

Ex. 0.08 mm (0.003 in.)

Decompressor free play:

1-2 mm (1/32 - 1/16 in )

Measure free play at the tip of the decompression lever.

I hope you get everything fixed up. These are great bikes. When I got my O4 XR400R

It made me realize how great my 350 really is.

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The valve clearances sound a bit too much. My 85 has the same values as tele-ski's 84. If you are getting good compression, it may not be the rings. I have seen quite a few motors where the oil rings loose their sealing ability but the compression rings are still good. The motors smoked really bad. The timing sounds like it is right. Make sure the front of the chain (towards the forks) is tight and the slack is in the back part of the chain (towards the carb). I hope this helps and good luck!

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