XR250L - Smoking a little on decel... Questions.

I recently picked up an XR250L a couple weeks ago and after a botched trailer miscommunication, I ended up having to ride it home three hours as opposed to towing it like I had wanted to D; It was a little wheezy and almost 'missing' higher in the rev range, which I suspected was due to the bike being jetted too lean.

For the backstory...

Made it home without too much trouble. It had been a pain in the ass to start at first, but I suspected that was again due to probably slightly tight valves, overly lean stock jetting, as well as me just sucking at kicking bikes over. Dug into the beast and adjusted the valves - they were a little snug and out of spec, but not terribly so. I had actually adjusted it terribly loose - apparently I wasn't on the compression stroke to find TDC. Bike tapped like crazy, and I turned the beast off after realizing my error. Let it cool down, and readjusted again in just a few minutes. Much better.

Cleaned / reoiled filter. Replaced the spark plug - it was terribly black/rich and smelled like gas. Did an immediate oil change with some Mobil1 10W30 full synthetic that I had left over from my old SV650 oil changes. Found that the idiot had put the filter in backwards. He said he had just changed it with Amsoil about 200 miles prior, with receipts to prove it, so I am guessing that given the freshness of the change and the total mileage on it at that point (320mi), it was probably not a big deal. Anyway, checked oil prior to leaving and after arriving back at the house. It hadn't used a drop.

Went through a couple more maintenance items... Replaced a leaky float bowl gasket, and rejetted the bike with a 40 pilot and 125 main. Given that the bike is running stock exhaust along with a simple Uni-Filter, that should be appropriate. The previous owner had turned the fuel screw many, many, turns out to compensate for the Uni-filter. We're talking 4-6 I'm guessing that he was rich on the bottom end, but lean up top. That would be consistent with what I found with the sooty black spark plug. Started wonderfully right after making those changes - the valve adjustment and the jetting. First kick.

So.. Here's the not so fun part.

Post jetting and valve adjustment, the bike ran much better. I recently dug into it again to check a few more things. I was trying to tweak the fuel adjustment screw to get it just right, as I had noticed some popping on deceleration that I was not a fan of. Ran great at WOT, with some popping on decel. I suspected the bike was too lean, and adjusted the fuel screw a bit more. Out of curiosity, I checked the oil at the same time and was shocked to discover that I barely had drop on the end of the stick. Shit shit shit, not good with an air cooled bike. Maybe responsible for the popping that seemed to appear, lean from overheating.

Filled it up with some Rotella I had on the shelf... slightly overfilled, so I used a syringe to pull out of the excess. Seemed to be some black mixed in with the newer oil, which I'm hoping was simply older oil mixing and not metallic. It didn't appear that way. Apparently, in the 350 miles since that first oil change, the thing had consumed damned near a quart of oil. That's about the amount that I put in - probably 3/4-5/6 a quart or so. That's a little distressing. There is no obvious smoking from what I can tell. After getting it buttoned back together, I started it up and looked for obvious signs of smoking. From what I can tell, I get a very trace amount at higher revs, as well as a tiny bit after releasing the throttle. It didn't appear substantial.

And now for any XR experts out there... Is this typical? I rechecked valves at the time of the oil fiasco discovery for shits, to find them slightly loose. (Checked cold, as per manual.) Readjusted, and the bike runs great. Hell - it lofts the front wheel better than it ever did before. I suspected worn rings may be responsible for the oil burning, as the bike has 9800 miles on it at this point, but given the performance, I suspect that the compression can't be all that terrible.

As an FYI, I use this bike mostly for commuting along with dual sport exploration of the area. Most of it is 50-55mph and under. Stock XR250L sprockets, 13/40, and do keep in mind that the XR250L has different 4/5/6th gears than the typical R. It is geared much better for the street. I've heard that XRs can use a bit of oil at higher RPMs, but I can't say I've been revving the living shit out of this thing either. Moderate beatings at best, nothing too harsh.

Please advise. Worn rings perhaps? Worse things? Given that it was run with probably a third of the oil it should have had, am I looking at serious damage? I cannot say for how long it was low like that. I had been noticing more popping on decel, which I can only assume can be attributed to the bike getting hotter and hotter due to not enough oil, thus running leaner. I plan to flush out the old oil today, and do a filter change while I'm in there. Like I mentioned, the bike still seems to be running great. I'm going to keep the riding local in the meantime, however, until I can figure out what, if anything, is wrong with her.


Edited by Yoshizuki

Where on the L is the oil level checked? Is it from a dipstick in the frame, just to the rear of the steering head? If so, there's a specific technique in which the oil level must be checked in order to get a proper reading. Not done, you can mistakenly get a low reading and cause you to add/overfill with oil.

L oil level is from the side of the cases... Just a small dipstick that is unscrewed. I generally check it with the bike on a Pitbull rear stand (use it primarily for my street bikes), which lofts the rear about 1/2" above the ground. It is essentially level when I check it.

From the evidence I've collected thus far from cross posting on a few other forums, it seems to appear that XRs indeed use a bit of oil... and that some smoke on decel, but not accel, signals valves / valve seals, as opposed to rings. And even then, that oil usage may be normal as this is primarily a street bike used for commuting. (<55mph) Hopefully that's the case. The smoking is fairly minimal.. We're talking about only a faint whiff under the aforementioned conditions... Nothing drastic - definitely no sort of smokescreen behind me for that matter...

k wait.. the oil filter was installed backwards???? you might be in a bit of trouble from that, especially since you rode it home. If its anything like my 350, if the oil filter was to be put in backwards, no oil could get to the top end. Hopefully I am wrong on this and its not the same for the 250.. but either way, good luck.

He actually had the spring on the wrong side, toward the outside of the engine. As follows...

Engine --> (seal)Filter --> Spring --> Cover

Whereas, the correct order is...

Engine --> Spring --> Filter(seal) --> Cover

The sealing rubber end of the filter wasn't pushed up against the cover, where the oil flows through... Given the arrangement, the engine had plenty of oil because the spring held the filter away from the pickup, but the oil was bypassing the filter completely. I'm glad I tore into it right away... Had he actually managed to put the spring on the engine side where it should have been, and still had the filter backwards, I don't think he would have even made it to the 200 miles he had put on the engine since that change. It likely would have been dead long before that. Small detail, but his double screwup may have saved the day.

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