I that the two plug looking bolts on the top and bottom of the valve cover? Sorry but I haven't got my manual yet and info on these quads on the internet is scarce. I tried pulling all the valve cover bolts and removing it but all I got was the comp. release lever falling off in my hand. I tried to pry it off gently but there's about 45lbs of silicone on that thing and it wouldn't budge. I don't want to go heave-ho on it and have a bunch of parts go flying in all directions because I didn't relieve the tension on something

 

Ok so I took a chance and took that valve cover looking thing off. I discovered that this houses the rocker arms which seems pretty cool. Long story short, the exhaust valve is stuck in the down position but still attached to the spring. The timing chain seems pretty slackish in my opinion so I'd say it probably jumped time. Guess I can expect to throw a piston and timing chain in it as well as a valve job... Makes me want to look into swapping a 300 King Quad set up in there.

 

If the valve didn't break off I doubt there's piston damage. I'd remove the head to find out, but only after buying a Clymer's manual for it. There's several tips in it that make R&R a lot easier. Trust me on this.
Mike

 

Yeah I know! Wish the damn thing would hurry up and get here. It better be here today because it's gonna be raining cats and dogs on Saturday and I want this bitch tore down asap. I'm looking right at it knowing what I need to do to it but won't proceed till I know exactly what I'm doing. If this were a car, I'd probably have it fixed by now but these old ATV's don't have squat on the internet to help you out. Reverting back to using actual physical books to work on things is beneath some individuals in this day and age but I'll do what I gotta do to get it done.

 

Ok so I got my manual.... copyright 1995 but it's all the same. I find that replacing the timing chain is an engine out, case splitting job so I'm gonna throw some guides on it and a salvage yard head. If it jumps time again, I'm swapping a 300 motor in it complete with oil cooler. Just hope the gearing compensation for the smaller front tires is in the front diff or I'll have to get some different front tires.

 

Take out the chain tensioner to see if it's working properly.
Mike

 

According to the manual, the timing chain is not something that goes bad often. It wants you to replace all kinds of things that wouldn't be considered a wearable part but it doesn't have a specific section about replacing the chain itself.

I have noticed several companies sell a manual chain tensioner so I would assume that is an upgrade from the spring loaded one that comes factory. All signs lead to guides/tensioner as far as I can tell so I won't plan on replacing the chain.

Head removal will commence tomorrow since I had to work 14 hours today..

 

You dont have to split the cases to replace the timing chain. I dont think you have to pull the engine either but cant remember for sure how the frame is made. Its well worth doing if its worn. The worst part of doing it is getting the magneto off. They make a special tool to pull it off.

The first ATV I bought with my own money was a 93 Quadrunner 250 4x4. It was blown up and needed a rod and several other things. I totally rebuilt the engine without a manual. Its a good thing to have a manual, but most these ATV engines are similar and the local dealer gave me the torque specs i needed. They are really good little ATV's. I ended up selling mine, but I have a 300 Arctic Cat now which is the same engine as the 300 King Quad, and it also has the lockable front differential and is a much nicer size for me (im not small. haha).

I did notice that on slow going, especially if there was much strain on it, my 250 would start getting hot. This 300 Cat has the oil cooler just like the king quad and it has yet to get warm on me no matter what I was doing with it. The oil cooler seems like it helps a lot. They are good little engines though and hopefully you can get yours going without much issue. If the timing chain is loose though, I would definitely reccomend going on with replacing it.

 

I was way off guys. Head was fine, chain was fine, valves were fine. What was wrong was a gallon of water sitting in the cylinder had created massive chunks of rust on the upper cylinder wall. Jug and rings and she's good to go lol

 

So the exhaust valve was stuck open w/ rust?? You didn't mention a new piston. I would get one because the water probably has pitted the piston also.
Mike