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DR350 smoking?

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I am looking at buying a mid 90's DR350. The owner stated that it runs fine when cold but after about 30 minutes riding it starts to smoke (blue he thinks). My first thoughts were the valve guides were shot and letting oil through the valve stems after enough oil got to the cylinder head. My old XR650L wore out the valve guides but after many years of hard riding. I do not want to buy this if it will be a problem child. What are your views on this? What would be a fair asking price for the bike with this problem?

Thanks

RH

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Usually parts in a motor will expand with heat and cause good sealing when warm. It sounds odd that it blows out the smoke after it's warm. May just be the bike running rich. When it's cold, it runs good but when warm begins to smoke a little. Also, the owner may have over filled the engine/frame with oil.

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The oil level is fine. He took it to a local independant shop to get checked out. He said they replaced a rocker arm and said that was the problem. I called bull on that. He said it stopped for a week after that then came back.

RH

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Oil is thicker when cool so it tends to not work it's way through worn or broken cracks when cold but when thinner can do so.

If you can get him to start it up and sniff at the exhaust even when cold it'll smell like oil if there's a problem. Blue smoke is oil and blackish is rich.

If it's older it may also be that a valve stem seal got tired brittle and cracked. If so then any engine will tend to burn oil. But it'll cost you to find out. May be best to shop elsewhere or offer a very low price based on the gamble of what is wrong. If it runs at all it's likely fixable with a couple of hundred dollars and a few hours of bench time. If you have a shop do your work then run away as it will NOT be finacially smart to buy an oil burner and then pay to fix it unless the guy practically gives it to you.

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Oil is thicker when cool so it tends to not work it's way through worn or broken cracks when cold but when thinner can do so.QUOTE]

If he was running a straight weight oil, then i'd believe you. With the multi weight oils, start up will act like the first number 10w and when up to operating temp will act as the second number for the specified oil 40. So whether cold or at operating temp, the oil will have a somewhat consistent performance. Yes, warmer oil will flow easier than cooler oil but the tolerances of a cold engine versus warm should make up for the cold to hot operation.

Also, do the plug check, that will be a great indication of how it's running inside.

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Thanks for the input. Any Ideas on the price I should offer? I have been a Honda man for years. The last Suzuki I owned was an 81' DS100. I do not know what they are going for.

RH

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...If he was running a straight weight oil, then i'd believe you. With the multi weight oils, start up will act like the first number 10w and when up to operating temp will act as the second number for the specified oil 40. So whether cold or at operating temp, the oil will have a somewhat consistent performance. Yes, warmer oil will flow easier than cooler oil but the tolerances of a cold engine versus warm should make up for the cold to hot operation.

Also, do the plug check, that will be a great indication of how it's running inside.

But even with the multi weight oils the warm oil is a fair bit thinner than when cool but perhaps not as big a change as I was describing. I know that when I drain an engine hot it's a lot more watery than when cool even with something like 10-40.

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Just as likely to be rings and/or piston/bore wear as anything else. Do a compression test. If the comp is low (find out what the normal range should be), pour a tablespoon of 10/40 down the spark plug hole , crank it over a few times and then re check the compression. If you see an immediate jump in comp, it's more likely to be a bore/rings problem (and the oil down the hole has caused a temporary seal), if it doesn't make much difference it's more likely to be a valve leakage (+ worn valve stem seals etc) causing the low comp. As previously mentioned by the other guys, blue smoke is oil burning, black is too rich. A black and wet/oily plug will confirm oil burning. Good luck!

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Oil is thicker when cool so it tends to not work it's way through worn or broken cracks when cold but when thinner can do so.QUOTE]

If he was running a straight weight oil, then i'd believe you. With the multi weight oils, start up will act like the first number 10w and when up to operating temp will act as the second number for the specified oil 40. So whether cold or at operating temp, the oil will have a somewhat consistent performance. Yes, warmer oil will flow easier than cooler oil but the tolerances of a cold engine versus warm should make up for the cold to hot operation.

Also, do the plug check, that will be a great indication of how it's running inside.

Just a little side note on hot oil from a recent hole in the side cover after riding hard for an hour in 90 degree weather off road using multiweight oil. it all ran out the hole like water not oil. oh and I worked in a refinery for 15 years. multi is not really noticeable unless the temps is extreme swing say from 10 degree to 60 in a few hours. so smell the oil if it smells like gas hall @%$#.

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