So i'm a noob to this whole riding thing as well, picked myself a 250r. Helluva deal! 8k miles, front fairings missing tho (laid down at a slow speed)...300 bucks!!! Mechanically sound and everything. One of my VERY experienced riders checked it over and steered me to this bike. I've already put over 1k this riding season problem free. Well, i was riding it to graduations this last weekend, bout a 45 min trip all interstate. I parked and talked for a couple hrs then got back on the bike...started great...ran great til bout 15 miles down the road...going about 85, not wide open (hiway)and she dogged really bad and died...didn't think anything bout it, switched the reserve on....popped the clutch, she started started up and i kept going. It died on me again. popped the clutch and she fired up, it started makin a bad knocking noises so i coasted to the closest farmhouse...andi ended up adding a QUART yes a quart of oil to it...generous guy...i know i know STUPID ME! and no the bike doesn't sound any better after adding oil to her....i pulled the plugs and it appears one of em is hitting the piston b/c the arc point was crushed down (.005 - .010 gap max).The marks on the elbow of the arc arm were the tip of its been "hitting" or just started hitting.....Then i found out spacers weren't put in whenthe plugswere replaced. Got new plugs, runs rough, and dogs to all hell...second gear running wide open is slower than normal second gear idling would be...also the harder i seem to get on it the doggier (bad word choice lol) it gets...but, my 2 somewhat mechanically inclined roomates swear the timing is off....i dont get how it could just slip going down the hiway at a consistent speed...so we dicked around alil with it (moved it one tooth back) and it seemed to get alil better but that knock and clatter is still persistant as hell, and the spark plug hasn't been bent again yet...the tensioner is VERY evidently worn, how often does that have to be replaced....i honestly have no clue how it's been serviced. i didn't ask, my fault...but still a 300 bike come on! lol....maybe it's a simple valve tune up and new tensioner? not sure but ANY information/tips/tricks to diagnose this would be GREAT!! ps - sorry for the forums longest thread, figured details are necessary!

 

The fastest thing to happen when your low on oil is you burn your engine bearings.

If you were fortunate enough to avoid that demise then it can be your plugs, if you run anything other than the correct NKG or NipponDenso for the 250 it will not run for long and usually ends with the plugs getting destroyed. I dont know the correctsparkplug number off the top of my head but I believe its on a label inside the left side faring that runs along the seat. If you dont see a label stating the correct rpm then pull the right side and check there, its under one of them.

You could have sucked crap into your carbs highly unlikely since it usually affects idle or acceleration. Its worth a shot to drain the tank pull the carbs take them apart and give them a good clean before you try to find a new engine.

The other thing that got me when I first got my 250 is it will look like theres enough gas in the tank but there isnt. But you said you switched to reserve and it still tanked right after.

As I have said many many times before check your oil every ride or every 100 miles or so if on a long freeway ride. They waste oil at high rpms and hold very little in the first place.

edited to add... I reread your post yes it could be the valves, a broken rocker possibly. Its hard to tell what your problem is exactly given the lack of history on the bike. I would start with getting the correct plugs NKG CR8HSA. Im still pretty sure you toasted your engine from lack of oil.

The tensioner life is not exact however all it does is make a huge racket when the engine is idle, I havent heard of one causing the timing chain to jump unless you turned the engine with the tensioner out.

 

if one of your pluges was smashed than make shure that you do a compreshion check there is a chance that you put a hole in one piston causeing loss of power and hight oil consuption

 

Man! i was afraid of that. The engine being shot. But, i'll troubleshoot some more befor i go looking for another motor....

The catch is i'm kinda sketchy with the plug scenario b/c i ran the bike for over 200-300 miles with those plugs... and the spacer that is NOW on the plug was about .02 ...the gap for the plugs are .028 which in turn leaves an .008 gap...and i could still see light thru the gap of the plug, but just a hairline, (aka the 8 thousands) and the backside had little imprints of contact at one point in time...we ran it for a very short time...pulled the plugs again and it wasnt crushed....

my coworker suggested the carb clean deal, but the bikeclinks and clunks while trying to start it...and when it actually does start, it's almost too much of clink, clunk and ping to be running lean or strong and doesn't even hold an idle...almost sounds like something is in the top of that right cylinder, if so what in the HELL could that be, may explain the bent plug too...something bouncing around in there contacted the plug on a stroke....

we took the valve cover off....springsappear to be ok, rocker arms are on the valve stems and dont appear bent, the roomate swore the timing was off so we moved it a link, that didn't seem to help at all...so i think he moved it back....

A coworker is gonna bring in a compression checker hopefully tomorrow if he remembers, and that could tell me alot, well timing or valve issue wise!

SO...worst case scenario....my bearings burnt up...that could cause extra piston slap, which could cause a fractionally higher stroke, and that could explain the bent plug and a horrible tick/knock noise when running and starting and causes it to be hard to start and doesn't stay running??? again ...that being the worst case scenario...how much does a 250 rebuild kit cost ...doing it yourself vs. not doing it yourself??

 

The motor is toast from running low on oil. Thats problably all that happened.