Ya I pulled those numbers right out of the manual. Even our import 125 quad is higher than 100psi. You should reach full compression after a few revolutions of the engine. It would not hurt to check your valves adjustment and make sure they are moving and verify your timing is on the mark

 

Yes,,Like I said in earlier post tight values or intake value can cause low compression I have seen zero compression and adjust values and retest compression an have 150..Yes tight values can cause and is main issues on 90 percent of low compression in my shop and area...just make sure your holding throttle fully open while engine turning over during compression test.

 

What brand of compression tester?

I don't believe it would even start on 35 psi. You would DEFINITELY be short on power if it somehow started with just 35psi. A small lawn mower engine usually won't run with much below 50psi usually with a max of 75psi.

Your other symptoms described in your original post have nothing to do with compression.

Pull the plug and hold your finger over the plug hole and crank it. If you only have 35 psi you should be able to keep your finger mostly on the plug hole. If you are around the spec (believe that motor calls 70-85 psi) it will blow your finger right off (off the plug hole not your body!)

 

Yes I have had some atvs that had starter turning slow and causes an false reading on compression gauge, does your atv have recoil[pull rope]start also? If so can test by pulling rope also and I think most atvs starter are around 600 rpm while starting if you have an timing light with rpm gauge on you can see the readings,,but still gauge values just to make sure there in specs so you can mark that off of list and go to the next test

 

Also alot of times an low compression engine can cause black carbon build up on spark plug if low compression makes low combustion which could lead to slow burning in the chamber which could lead to carbon build up and rich burning lack of combustion burning,yes can have fuel issues also just trying to get the basic took care of before the part changing starts.Also slow turning starter can cause slow engine rpm while starting which can lead to excessive fuel build up in chamber which cause starting issues and once engine starts will run good and have power....we just always check ignition peak voltage and than compression test before we do any other dianosing on running and start ups issues than we go to fuel systems cause if engine doesnt have them 2 items than fuel system could show an false test

 

I REALLY appriciate everyone helping me here. I don't want to sound sappy, but I really really thank you all.

I see lots of people have posted since my last post. I will go back and address them once I put this information out. I have short term memeory issues so I need to get my info down before going back.

1) I went out and checked the compression cold. Same psi as last night.

2) I left the tester in the cyclinder last night without relieving the pressure. I was curious if the pressure would hold or drop. It was only down to 20 psi from 35. So would that tell me its NOT the ring? If it was, wouldn't the pressure drop right down to 0? When I pushed the release valve on the tester, it deffinitely had air coming out

3) Next I warmed the ATV up for a good 15 mins. Engine was warm. I did the compression test again at WOT.. I'm getting about 55 psi now. I repeated the test a few times, same result. I did need to crank it a lot to get it to fire up and hold the throttle slightly open. I think this might have been due to the fuel being dumped in the cylinder

4) I've got really bad short term memory. I completely forgot to add a ounce of oil to the cylinder and check compression. Memory is very bad. If I don't; write it down, I forgot. I forgot to write this step down. I will do it tomorrow night.

5) I pulled the tester out of the cylinder. Before I put the plug back in, for ***** and giggles I held the throttle wide open and cranked it. A really fine mist of air/fuel mixture shot out of the cylinder each crank. The fine mist shot out of the cylinder about 3-4 inches. Would this not mean the injector is good?

6) My starter is cranking at about 19 cranks per 10 seconds. So about 115 full rotations per min. I set a timer for 10 seconds than cranked it WITH THE SPARK PLUG IN TIGHT. I counted 19 full cranks. The battery is a month old and has a battery tender jr. on it every minute the ATV isn't running, so battery isnt the issue. I always remember the starter not cranking fast. I own a new honda rubicon and that thing cranks FAST compared to my cat. I can see a bad starter causing the atv to have a hard time starting, but could it also cause the other issues? I'm thinking over time, because it slow cranks it might foul the plugs up. Once the plugs are really fouled up, my issues start all over again. I did notice when the ATV has new plug, it seems to run fine. But it fouls plugs fast.

7) I'm not sure it matters, but the atv has about 5,800 KM or 3600 miles.. About half those are hard riding. Its NEVER been swamped. I've always used ams oil full synthetic and I change the oil very regularly. In general the oil/filter gets changed in the spring and again in the fall. The only time it didn't have ams full synthetic is during the 300km break in when I used arctic cat oil.


I'll go back and address the new posts. Thanks again

 

Thanks!!! my issue could deffinitely be the slow turning starter. Would explain why it eats batteries as well.

how do I check ignition peak voltage?

 

Im far from 600 rpm on my starter.

No pull cord.

No timing light. I'm not opposed to buying one if it prevents throwing parts at it.

 

My compression tester I know its not going to be the best, but I can't see it being off more than 10-15 psi. I live in a remote area so I order all my tools and parts. I could test the compression of another motor to make sure its not the tester giving me a bad reading.

I was taught to use my finger to check compression when I was about 8 years old, but completely forgot about it.

I'd like to know what psi it should be. I read 70-85 psi as well and others are saying well over 100. I might call a dealer ship tomorrow.

 

8) I forgot to add, when I checked compression it jumped up to 55 psi really fast. 2 full rotations and it hit 55 and stayed there. Not sure if that helps.

I found this on line which states my starter should be rotating at 400 rpm and my compression should be at 70-85psi. This site is for a 2009 and mine is a 2010. Would the compression be the same or do I have a different motor? I realize around 2009 Arctic Cat switched who made their 550's.

https://www.slideshare.net/hjksemmys...-repair-manual

2 3. Remove the spark plug(s); then attach the high tension lead(s) to the plug(s) and ground the plug(s) on the cylinder head(s) well away from the spark plug hole(s). 4. Attach the Compression Tester Kit. NOTE: The engine must be warm and the battery must be fully charged for this test. 5. While holding the throttle lever in the full-open position, crank the engine over with the electric starter until the gauge shows a peak reading (five to 10 compression strokes). 6. If compression is abnormally low, inspect the following items. A. Verify starter cranks engine over at normal speed (approximately 400 RPM). B. Gauge functioning properly. C. Throttle lever in the full-open position. D. Valve/tappet clearance correct. E. Valve not bent or burned. F. Valve seat not burned. NOTE: To service valves, see Section 3. 7. Pour 29.5 ml (1 fl oz) of oil into the spark plug hole, reattach the gauge, and retest compression. 8. If compression is now evident, service the piston rings (see Section 3). Spark Plug(s) A light brown insulator indicates that a plug is correct. A white or dark insulator indicates that the engine may need to be serviced or the carburetor (if equipped) may need to be adjusted. To maintain a hot, strong spark, keep the plug free of carbon. ATV-0051 Adjust the gap to 0.7-0.8 mm (0.028-0.032 in.) for proper ignition. Use a feeler gauge to check the gap. ATV0052C When installing the spark plug, be sure to tighten it securely. A new spark plug should be tightened 1/2 turn once the washer contacts the cylinder head. A used spark plug should be tightened 1/8 - 1/4 turn once the washer contacts the cylinder head. Muffler/Spark Arrester At the intervals shown in the Periodic Maintenance Chart, clean the spark arrester using the following pro- cedure. 1. Remove the three cap screws securing the spark arrester assembly to the muffler; then loosen and remove the arrester. PEAK COMPRESSION MODEL PSI 400 95-115 500 70-85 H1 Models 155-175 H2 Models 75-85 (Front) 120-130 (Rear) ! CAUTION Before removing a spark plug, be sure to clean the area around the spark plug. Dirt could enter engine when removing or installing the spark plug. ! WARNING Wait until the muffler cools to avoid burns.