View Full Version : Need Input 1991 Arctic Cat 440 LC Top End/Ring Replacement
10-07-2009, 06:36 PM
Need some help guys, thanks in advance:
Had 90(LH)/100(RH) psi compression on my 91 Arctic Cat 440 LC and decided to overhaul the top end with new rings. All done, but my compression did not change. Still reading same compression. No indication of a chamfer or stamp on the rings of a top/bottom.
I was thinking I read somewhere I should see around 120 psi compression?
did you run it to seat in the rings? Also try a different compression guage,first dry, then with squirt on oil in each cyl to see what happens
usually takes 100 psi to run
10-07-2009, 07:16 PM
Runs fine. Forgot about the oil squirt for bad ring check.
Did that check initially to make the decision to swap out rings.
Not overly concerned since the sled runs fine. Just wasn't sure I got everything back together correctly causing the low(?) compression.
I thought in 91 cat was still putting a dot on the up sid of ring.did you get the jugs honed?
10-08-2009, 09:23 AM
I did not have the jugs honed.
I had done the compression check as suggested by ubee by adding oil to the cylinders. It raised my compression from 90/100 to 110/115, so I elected to replace the rings.
Dennis Kirk gave me two options for the 91 440 LC rings: 68mm or 68.5mm. I elected to use the 68mm per my overhaul spec's.
I looked the rings over hard outdoors in the sunlight looking for the top/bottom markings and/or chamfer as the overhaul manual suggested, but could not identify any markings. They were as square as I could see from the naked eye.
Sled starts and runs fine. How long should I run in the new rings? Today, I will check the compression again, dry vs oil.
Thanks again for your time and help.
10-08-2009, 09:35 AM
Did you put your rings in the jugs by themselfs and check the end gap...(you really should have honed those cylinders to "clean em up" and give em new hatch marks. Kinda late for all that now but they do need to run for a while to seat. Need to get that motor warm. Been a while since I worked on a cat but off hand cant remember ever replacing rings on a sled that didn't have a "bevel" have replaced a few that didn't have a dot on them though.
10-08-2009, 10:13 AM
Thanks for the reply dab,
I did not check the end gap as you suggested.
Typical first time "do it yourselfer" tried to rush thru this project on a limited budget.
What's my risk leaving things satus quo?
I have time to start over, but I'm not sure what my best compression expectations should be.
10-08-2009, 11:54 AM
Short term risk, nothing, low compression. Likely hood 60% if no bevel on rings. Call Kirk and see if they can tell you if there is a bevel. Short term if there is a bevel I would say a few hundred miles maybe, maybe nothing will happen. One thing is for sure if something happens it will cost more then rings and gaskets. If I was to start over (and I am sorry I assumed those things were checked first.) I would take your new rings and end gap first. (That way if you need the others you have time to get them while the other stuff is getting done.) Take those cylinders and hone them. If you ain't got a hone take it to a shop that does. Should only cost around $10 a cylinder. Then when you get them back recheck (or check with the new rings) the end gap. Use a magnifying glass to look those rings over good for a bevel. It won't look like much. If you have a mic, mic the inside and outside of the ring to see. Big advantage to doing it now before you get to much run time is you probably can use everything you have now cept new gaskets. If you run it to long, even if no damage still have to buy gaskets and rings. Plus now you are on a time line. Still have a few weeks before snow, hate to go down once snow it on the ground, may only be a week if you are waiting for rings and gaskets, may be a month if pieces get down and tear the crank up. Compression wise I would say close to 120. Biggest thing is no more then 10% difference between the two cylinders. Different compression gauges read different. I have one of those "push in" ones that read different then my Sears screw in one. and my Sears one reads different then my buddy's snap on one. Hope this helps and I don't think I missed anything, oh yea I would run a tank of pre-mix thru it the first time also. And mark you oil tank to make sure you are useing oil that first tank. Did a top end one time thinking the miles took the rings out to find out the oil pump did it and I had to re-build again.
10-08-2009, 02:31 PM
Quick update and thanks for everyones help:
Now that I understand the difference between a "bevel" and a "scarf", I now know what to look for.
Decided to tear back down to ensure I get everything together correctly. Sure enough, I had one ring per side upside down per side.
Heading out to have jugs honed and pickup feeler gauge. Near I can tell, end gap will check within .008" max tolerance at several locations (specifically around exhaust port).
Let me know if I'm heading down the right path guys. I sure appreciate everyones help again!
10-08-2009, 07:42 PM
yep that's the way to check it. make sure u use the piston to put your rings in so you know you are "square" with the jug. Just start your ring by hand and then use the piston to push it up into the jug. Don't know where you are taking your jugs to have them honed but if it is a sled shop don't be afraid to tell them you are new and this and see what advise they can give you. Sounds like you got a pretty good feel for the process so it will be easy to tell if someone is just trying to sell you services you don't need. Also since you did all of this did you check (actually I would replace) your needle bearings. Also check your "side" play on your rods. Shouldn't be much if any side play. Should move back and forth on the crank but not be able to "twist". I am sure on that age of a sled somewhere on the net should be able to find a free service manual or at least on here someone should have one hid in there garage somewhere. Been a lot of years since I worked on green but there all the same to some extent.
10-09-2009, 04:43 AM
When I re-read your post I see you said and overhaul manual. Are you refering to the paperwork that comes with piston sets or do you have a service manual for the sled.
10-09-2009, 10:12 AM
Thanks again for your response dab.
Yes I have a Service Manual for my sled.
Unfortunately we don't have any sled shops here in Wichita KS. The one cylinder repair shop I spoke with yesterday did not want to undertake the task of "cleaning up" my aluminum jug. I'm thinking about going back together without doing anything to the jugs.
There is a Cat dealer 36 miles away. I'm calling them today and check for prices.
Rod side play is minimal with no twist movement whatsoever.
If they are nicasill coatings factory does not recomend honing, i have always used acid to take out any aluminum deposits and used a hone ball to cut any glaze and have been pretty sucessfull unless chrome is chipping, then time to replate.used to be place that advertise on jd for that.
10-09-2009, 11:28 AM
second what ubee said. I don't think they are nica though. Not positive. Call the cat dealer or a place that sells re-man cylinders. Can't remember exact name but can find one in the back of any sled mag. Take the money and time you would spend in going back and forth to the dealer and by a hone. Unless it is nicasill. If it is nicasill a regular hone won't touch it, needs to be a diamond hone. But on the other end of that if it is nicasill unless it is chipped odds are it isn't damaged. That stuff is like a diamon. The reason I asked about the service manual is it should tell you in there what your slop and play should be on the rods-2-crank. Since you already bought the feeler gauges gives you a second place to use them.
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