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Ran low on oil, makes knocking noise

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Here's some backstory : last year, I rode this bike on a 1500 mile round trip, and it didn't use oil at all.

Generally, I change the oil and filter ever 1000 miles.

In October, I took it on a dirt ride, which was quite dusty. When I was cleaning it up after the ride, I noticed that the crankcase breather/oil vapor hose from the valve cover had pulled out of the airbox (actually it was the hard plastic elbow that pulled out). There was definitely dust inside the hose, and evidence of dust on the intake bell of the carb.

[As an aside, this is one of the very few things I really disagree about with Suzuki's design of the DRZ -- if that hose pulls out (very easy to do if you are tinkering with the carb) it opens a hole on the wrong side of the filter, allowing the motor to ingest unfiltered air. So, make sure to check this hose if you work on your carb!!!]

I just got home from an 800 mile trip yesterday, and when I pulled in for the last gas stop it sounded fine, but 30 miles later, when I got off the highway, I noticed the motor was knocking/clattering when I accelerated from a stop sign. We're not talking "RUN AWAY, SHE'S ABOUT TO BLOW" kind of noise, more like "Uh oh, that wasn't there before"

Before I left, I did check the oil, it had about 200 miles on it, was at the correct level, and looked clear and new-oil-colored on the dipstick.

I changed the oil today. Between the frame and the sump, I drained probably only about half a quart. It was definitely darker and thicker than usual, and smelled burnt. There were no metal flakes in the oil, and no metal on the drain plug.

Out of curiosity, I sawed the filter open. There were a few 'grain-of-salt' size flakes of metal visible to the naked eye. At this time, I noticed that the smaller inside O-ring was missing, and I have no idea how long it has been missing.

With fresh oil, I took it up and down my street, and the clattering noise is lessened, but still there. Clearly, I'm not going to ride it until it gets fixed.

To those that have done similar damage, what usually goes first? Or, do the major things (rod/crank/piston/valves) all seem to go wrong equally at the same time? I'm hoping I just need to put a big-bore on it, and ride happily into the sunset.

Eddie, I'd love to hear your thoughts on the kind of damage I've done, what to look for, etc.

Also, what are the chances that I can have this motor back up and running in under 3 weeks? I'm a fair wrench and can mostly follow directions (said the guy that left the spacer out of the kick-start kit). I'll probably have the motor out and top end off tomorrow by lunchtime, if my clients don't interrupt me too much.

Eddie, what is your turn-around usually like for this kind of rebuild?

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Yup, sounds like the crank big end. "Hello, Hot Rods, got a stroker for me....."

Being it is barely the beginning of the riding season, turn around hould be fairly quick. Larger issue is parts availability/delays.

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At this time, I noticed that the smaller inside O-ring was missing, and I have no idea how long it has been missing.

Wonder where it went...maybe it was stuck to the old filter when you replaced it?

Does not having the O-ring in place affect oil pressure?

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Yes, I'm saying it went from full to half a quart in 800 miles.

That's why I mentioned the dust incident -- I suspect that I have damaged the rings or cylinder, causing the oil consumption. The plug was a little darker than I'd like it, but not as sooty as I'd expect for consuming a quart of oil. This part has me pretty concerned.

Regarding the O-ring, I checked the filter, it wasn't attached. I think on a previous oil change (last one, most likely) I simply didn't check and it went in the trash with the filter.

I'm really conflicted - I have tools & skills, but not so much time, and it's possible that I could not meet my 3-week deadline. Plus, I don't want to build a race motor -- this is a daily driver.

Eddie, is it possible for you to turn around a BB/Stroker motor (3-ring piston w/spacer) within that period? The only other work I'd want is RHC valves. Can you PM me with cost & turnaround? Thanks!

My other option is to buy another stock motor, but I don't really want a second motor lying around...

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Eddie, PM sent.

And, thanks for your input! You perform a valuable service to the community by generously sharing your experience.

BTW, I know, can't diagnose long distance, but does it sound to you like a crank/rod problem?

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