Hi All!  I bought my '87 last summer for commuting to work and put maybe 500 miles on it before parking it in the garage for the winter during which I made the mods identified in my signature below.  She fired right up last weekend and I tuned the carb.

I began an oil change and while I was carefully removing the oil filter cover discovered the P.O. (or?) had failed to reinstall the spring with the new(?) K&N oil filter.  

I have one on order, so while waiting I am going to remove the clutch cover and do some inspection (cam tensioner) etc.  Any suggestions on what else I might want to check for due to improper filtered oil?

I am the 3rd owner, the 2nd owner only had it a couple of months and hadn't even transferred the title yet when I bought it.  He had to sell due to medical issues.  The bike just turned 8k miles.... Thanks!

Thanks!  Me too... she ran okay before winter and tons better after the mods.  I know the oil was circulating before because it developed the infamous plug cap leak which I repaired along with the mods.

O-ring was there... just the thought of unfiltered oil circulating throughout has me concerned.  If I find nothing else, I plan to change the oil again in maybe 200-300 miles to flush any nasties out.

Thanks Again!

The 4 wheeler, a Yamaha 250, has no oil filter. Its gota a screen, but its not a fine mesh. More of a strainer,,

Routy, not real familiar with Mules, but I think you have a spin on oil filter located directly under the cylinder jug.