Well I just finished adjusting the valves, cleaning the air filter and an oil change on my girlfriends 2004 zzr250, same as a ex250.
she had a tune up done a long time ago before we met at a local well know shop. She show me the bill where the work was done. They did an oil change, spark plug replacement, lubed chain/cables and cleaned that airfilter. I though they did good work so she just rode it as is until i started working on it. I fixed the oil filter assembly the first time i changed the oil, the rest i discovered as i was doing the valve adjustment.
1. cross threaded body work screws, 1 out of 4 was cross threaded. seems like they used a electric drill to screw them in.
2. oil filter assembly was not assembled properly. its suppose to be like this. http://faq.ninja250.org/wiki/File:OI...L_FILTER-2.png
it cause low oil pressure on cold starts and you had to rev it to turn the oil light off when cold. i did not change the oil viscosity. it was installer error that caused it.
3. air filter is a foam washable filter thats suppose to be oiled. no oil and improperly installed. oil could have dried up but it just stuffed in the air box filtering maybe 50% of the air if i was lucky.
how it should be. http://faq.ninja250.org/wiki/File:006.jpg
and the lid was on backwards. http://faq.ninja250.org/wiki/File:016.jpg
4. wrong spark plugs installed. wrong heat range.
i don't know if they were lazy or not qualified.
Now that i fixed everything, it runs like a dream and hopefully there was no permanent damage.