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Help with Diagnostics

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I’ve been using this forum for quite a while to learn more about my 2002 DR650 and have found this to be incredible information source. I’m going to put you guys to a serious test here. My good friend recently bought a 2006 DR650 with only 1300 miles which is bone stock and unmodified. Until last year it had only accumulated 600 miles. It runs very well, in fact a bit stronger than my ’02 with 11,000 miles. The problem is that on a cold start up it puts out a noticeable amount of blue smoke until it warms a bit, usually about 30-90 seconds or so. The plugs look fuel rich and show a bit of wetness on the last few threads. To me, a former 1960's/1970’s Honda and Yamaha mechanic, it smells oil rich and at times fuel rich. We have checked float level (15mm), idle mixture screw setting (1.75 turns out), main jet (140), spark at both plugs, breather tube is unrestricted, fuel is fresh, oil level is between full and low lines (Shell Rotella synthetic), air filter is clean and lightly oiled, the float valve closes well, and I’m out of ideas. I do not know how to assure that the enrichener is seating properly when turned off but the cable has slack when closed. It almost seems like an intake restriction, such as something in the air box in front of the air box screen, but it runs so darned well that’s hard to believe. What is unusual to me is that when we remove the air filter and leave the air box cover off, it will not take bursts of throttle. At mid range RPM it sputters and coughs terribly under no load. It seems as though it’s even more restricted. With the filter back in it runs beautifully. Absolutely none of my 8 years experience as a motorcycle wrench has helped me diagnose this issue. I’m down to thinking that either the valve guide seals are bad or the previous owners never properly broke in and seated the piston/cylinder. I saw that a few times on Hondas in the early 70’s and recall having to hone/deglaze a few cylinders when new owners babied their new motorcycles so much they never got run hard enough to seat the rings. But my recollection is that those smoked all the time, not just when cold. At this point I've suggested he go back to non synthetic oil and run it hard for 500 miles or so while monitoring the oil level. And we have not ruled out the possibility of two separate problems. If any of you guys who have extensive experience with the 650 have any suggestions or thoughts they sure would be appreciated. Perhaps it's just because it's yellow?

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I'm gonna assume that the valve guide seals are bad from so much time spent parked. Thats why it only smokes at start up.

When you remove the air filter, you are leaning it out.

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I realize that filter removal leans it a bit, I've just never seen that response before. These suckers must be incredibly lean to begin with if filter removal causes fuel starvation. Is there any type of test for valve guide seals that I'm not aware of? Logic would point that way, but I hate to do a tear down without a little more evidence. I would suspect seals in an older bike, but this is just six years old.

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I'm gonna assume that the valve guide seals are bad from so much time spent parked. Thats why it only smokes at start up.

When you remove the air filter, you are leaning it out.

My 08 DR runs perfect with the air filter in. Bogs bad with it off.

Might check that the air box isn't full of oil and gas. Remover the rubber tit on the bottom of it. It should have never been there. From your description it sounds like a bad intake valve guide seal. But check the simple first.

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I'm gonna assume that the valve guide seals are bad from so much time spent parked. Thats why it only smokes at start up.

When you remove the air filter, you are leaning it out.

My 08 DR runs perfect with the air filter in. Bogs bad with it off.

Might check that the air box isn't full of oil and gas. Remover the rubber tit on the bottom of it. It should have never been there. From your description it sounds like a bad intake valve guide seal. But check the simple first.

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I think we have checked all the simple stuff, but I must admit, while we did inspect the air filter box for oil and gas, but we did not remove and inspect the outlet tube between the air filter box and the carb. To some degree it's encouraging to hear that your DR acts similarly without the filter. I still wish I had a more definitive way to test the valve guide seals before disassembly. Do you all feel that when the bike only had 600 or so miles on it the first five years that such inactivity allowed the guide seals to crack and/or fail?

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Do you all feel that when the bike only had 600 or so miles on it the first five years that such inactivity allowed the guide seals to crack and/or fail?

I do. And yes, they come from the factory set too lean.

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Here's another for the experts. Is there any way to fill the combustion chamber with something (rope, string, compressed air) to hold the valves up, then compress the springs enough to remove the retainer clips, all with the head still on the bike? That would save disrupting the top end and a bunch of time. Plus I don't own a valve spring compresser.

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If you are sure you are smelling oil then it certainly could be valve seals.... although this is certainly not a normal issue with the DR650. Your 1.75 turns out on the pilot is about a 1/2 turn too rich give or take a bit... the DR650 has a propensity to create quite a bit of condensation in the exhaust system which can look blueish/smokeish. You will get spits of carbon mixed with the water looking like rust coming out of the stock Buick muffler. Just be sure you have a real problem... The stock air box is highly restrictive..... with the cover off your machine will idle and accept around a 1/4 throttle... maybe a bit more then fall flat on it's face. The stock air box is the performance restriction point on a stock machine... the stock muffler does not take it's turn in that position until the air box is opened up along with the appropriate jetting changes.

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I like your first plan, replace oil with conventional and run it hard for a couple hundred miles.

Also while draining the old oil smell for gas. I have far less faith in the float assembly mounting "O" rings than the valve seals. The air-box drain is not between the filter and the carb as far as air path. It is before the filter so air entering will still be filtered. The DR's BST carb doesn't have a normal float bowl vent hose, it's vented through the carb body. Flooding fuel can enter the intake and air-box as it has nowhere else to go.

I would do a little more checking before tear-down. I know the symptoms sound like seals but they haven't been a common problem. More likely rings not seated do to EZ brake-in with synthetic, or raw gas washing down the cylinder walls and thinning the oil do to carb flooding.

Normal for a modern EPA bike to be lean almost to the point of not running. Any mod which leans further (like running w/o a filter) can make them unridable.

Bruce

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