Has anyone here done any valve work on the arctic cat 250?

I have an '01 250 4x4 that burns oil. It is really bad at start up, so I think the valve seals and/or guides are worn and allowing the oil to leak past when sitting.

I am wondering if it is something that can be done in the home garage or if it is best taken to a shop. I am not new to working on engines, I just usually work on automobiles.

 

Valve work is not terribly complicated but you do need the service manual for the specifics.

How much oil is it burning? How often do you have to add it and how much? Both my machines put out a lot of steam from the exhaust when I first start them up until they come up to temp. I do not need to add oil between oil changes.

Swampy

 

I have the service manual, but they sometimes over simplify things. Like, remove this part, and then you find it is better to have many $$$ in special tools to remove that part.

I have looked over the procedure and it doesn't seem complicated. Just wanted some opinions from those who have done it. Specifically on the valve guides, I am thinking those will need replaced as well. It burnt a half quart of oil on a 20mi ride.

The problem arose from the needle and seat in the carb going bad and letting the crankcase fill with gas. I think the gas had filled the crankcase and sat for a few days before I noticed. I then rode for about an hour before parking and noticing the oil window was completely covered (over full). I drained and refilled with fresh oil, road for about an hour, and then changed oil again to flush the gas out. I think the gas lead to the seal on the valve failing and may have caused the valve guide to become worn. But until I tear it down, I just don't know.

 

thats a very simple to work on. u can pull the head and cylinder off with it in the machine. you just have to remove carb and exhaust first. no special tools required. sounds like you need a rebuild and a valve job. i would do them both while i have it apart and it will last for a very long time if you break it in properly

 

Newport-

Sounds like you have done some valve work before. Do you think the valve guides will need replaced?

The lower end doesn't seem to have any problems, you think I need to rebuild everything?

 

When I rebuilt the top end of my AC400 I replaced rings, piston , timing chain, cam, etc as well since it was torn down. You have to look at WHY are you needing to do the valve work. I had to do mine becasue I lost oil pressure (or oil flow at all) to the top end and seized the cam. So I chose to do the piston work as well just in case. (I have about 10,000mi since then)

If the engine was ran with it low on oil top end may be all you need. Most often they are ran too low or too long with fuel in the oil and it takes or damages the bearings and seals out on the lower end and tranny as well.

Swampy

 

The reason why is related above. I have cured the carb problem. It just uses quite a bit of oil and smokes constantly. I removed the oil fill plug and the smell of exhaust is not strong in the crankcase nor does it seem to have excessive blow by. It runs strong, just smokes.

I gues what I am wanting is opinions on what may have happened to the lower end or what may become a problem. I am fairly certain the valve seals are gone and the upper end needs rebuilt. I don't notice any knock from the crank.

If the entire engine needs to be rebuilt, I am sending it to a shop. I don't have the time to do that myself, I am in the middle of remodeling my house.

 

Sorry I skipped over the carb fix mentioned above. That is a tough call on what to do.

If it were mine,knowing the top end MUST be done to solve the buring oil problem I would contact a dealer and ask how much for the top end rebuild (get a $ amount with a cost and parts breakdown). Then I would get another one for a total rebuild ( $ amount and cost breakdown).

Look at the difference in price and see ehat you get. Also ask if you can save them some time and you some $ by removing the engine from the machine if you go the rebuild route. For peace of mind if you can rebuild the engine for $500-800 more than gettingthe top end done I would personally choose that.

I personally would not like putting $ into the top end, then riding it for a while and then have to go back and pay more $ to tear it apart again and have the lower end rebuilt. These things are not like cars where you can remove the oil pan and get at the bearings. In an ATV you have to remove the top end and split the case.

Since you are not new to engine work skill is not an issue. But Time and $ probably are. If it were mine I would do the lower end as well just to be safe. I fyou do not have the $ right now you can either ride it as is until you do OR dothe top end now and know you may have issues later with the lower end.

Hope this helps

SJ

 

I think I will do the top end. If I can get through the winter I will have some time next spring or summer to look at the rest or take it to a shop. It is my primary snow shovel!

 

You may know more too when you take the top end a part. THe piece to look at is the cam bearing surface. The cam is steel and the bearing surface is aluminumm. So when you do not get the proper lubrication the steel wins and the bearing surface gets eaten pretty fast and then you hear a loud tapping noise. Made my AC400 sound like a diesel!

As a result I did not rebuild the top end I repalced it. I reused my valves and everything else was new. Made things a little easier but I spent a HUGE amount of time checking to see if the cam and head were OK and within specs. In the end they were not and it was far easier to just repalce them. Not to mention the time it saved me.

Good luck, and hopefully you can get-R-done before it snows!

Swampy