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XR650R Bike ran possibly lean blowing black smoke, should I be concerned?

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Long story short, I serviced my shock by pulling it out of the top, and after reinstalling did not notice the air boot had come off the carb. I went on a 150km ride and when I went over 4000rpm it would sputter and had no power. Most of this was all hwy speeds with good air flow, so I was not overheating the engine. I was able to identify the air boot when we got back to the garage. While running it spit out a lot of black all over my license plate. The air boot was not all the way off, maybe a 20mm or so long gap 3mm or so wide. It may have been just running bad/lean due to the air not being properly directed into the intake of the carburetor through the venturi.

Plan is to pull the plug and stick a video scope in there to see if I did any melting/damage to the piston. I'm hoping the scope I have is smaller than the spark plug. I suspect it will be difficult to see the valves with the scope but I'll try.

I will check the valves as well next oil change and make sure they are good for the trip.

It does run just as normal now, so I am not super concerned, but I am planning a very long multi-day ride coming up in August.

Anything else I can easily check? Or am I being overly cautious?

When I think about it, even running without an air filter would be similar effect, just the air would be directed properly through the venturi of the carb. So I'm not sure if I was experiencing a lean condition or just bad combustion.

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Chance are the black deposits are carbon build up that has been blasted out your exhaust because it was getting a higher air flow...................more in more out

If it runs fine you are ok, check your plug for color (put in a new one)

change oil and see how it does.............................

you can "bag" the rear of the exhaust with a pillow case (ride for a minute at hwy speed) to see if the debris is dry or wet............... carbon will be dry

you just cleaned the exhaust pipe I think.

 

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The CV carb needs the air box vacuum to operate correctly...................... I should not sputter now if you hooked the boot up

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Posted (edited)

Thanks guys, yes it runs fine now. I'll look into the plug hole and replace that plug. It looked more like a dry black then wet, so probably just carbon deposits. 

Edited by Rider Eh

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