1998 srx 600 compression?

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schlepp27

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Feb 8, 2008
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Hollis, ME
I just purchased a 1998 SRX 600 and I did a compression check prior to purchasing. I am a little nervous about the compression, but I got such a good deal on the sled, I couldn't pass it up. The compression is 118 psi PTO, 118psi Center and 107psi Mag. The engine runs smooth and seems to have plenty of acceleration without any hesitation. I know the compression is low, but what really concerns me is the mag side. Does any one have any input on what I should do? Could I keep running this sled for the remainder of the season, or should I redo the top end? It currently shows 1790 miles on the odometer. Any input would be much appreciated. Thanks in advance.
 
Yes. I tested at op. temp, throttle wide open and about 5 pulls for each cylinder. I tried several times using two different compression gauges. The highest readings that I received was 120psi pto, 120psi center and 107psi mag. I then put about a teaspoon of yamalube in the mag cylinder and retested. I found that the compression bumped up to 110psi (Not a significant change).
 
pull them out and clean them and the cylinder housing they sit in
 
Yep they slide right out it would only take you about 20min...there are a bunch of post on here about how to do it....I bet that you either find one stuck or it is pulled through..do a search!
 
I pulled out all the power valves, cleaned them and re-installed them. Imediately my compression went up in all cylinders. I noticed the cylinder with the lowest compression came up to 115psi, but the power valve didn't seem to extend out as far as the other two. After running the sled for a bit, I checked compression again and the problem cylinder was down to 100psi. I think the power valve is stuck in the open position. How do I get it unstuck? Also, I readjusted the power valves in accordance with a post by Daman. Any ideas? Thanks in advance.
 
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did you clean the groove's in the cyl.?

when done cleaning make sure the valve slides in and out freely by hand.
 
The valve moves freely in and out of the cylinder, but it does not seem like it extends out as far as the other two. I didn't completely remove the valve. Should I completely remove the valve from the cable and clean the shaft end of the valve as well? I believe that the valve is not inserting all the way. However, there isn't any restriction in the cylinder. If I remove the valve from the cable, is there anything that I need to be cautious of? Thanks.
 
no you'll be fine to remove the cable.just pay attenton to what your doing.:)
tapper on the pv goes down!!
 
Ok, so I removed the power valves and cleaned the entire valve. After reassembling, I performed a final comression check. 130psi pto, 127psi center and 112psi mag. I put about a teaspoon of oil in the mag cylinder and performed a compression check, 120psi. Sounds like I need to re-ring the mag cylinder? What do you guys think? I'm thinking that the maintenance of the power valves was never performed and that was probably what resulted in the premature wear? With the above compression readings, would you guys re-ring the mag cylinder ASAP or wait till the end of the season? I figure I might throw on 300 miles or so the rest of the season. I want to be able to enjoy this machine without the worry of further damaging the engine. Any input would be much appreciated. Thanks in advance.
 
depends on what you want to do,you want to run it or work on it,a leak down test would be a better indicator of ring health,tear the top end down and check spec,,worse case your out some gaskets,have the parts/tools on hand and you can do it in an afternoon..
 
i would pull the exhaust pipe and inspect piston to see if it is marked also check servo for cables to make sure they are connected to the wheel inside as i had a customer do it himself and wind the cables the wrong way
 
run it. remember it has been sitting, maybe a ring is stuck and not sealing well. you said you'll only put on 300 or so miles right. do that and then recheck.



blue
 
Well, I did a little inspection of the pistons. I was able to take a small mag light and shine down the spark plug hole while the pistons were at BDC. I could see the infamous exhaust side melt down on the mag side piston. This would be the reason I have low compression in that one cylinder. The top ring appears to be intact at this point in time. I may get lucky by only honing out that cylinder and replacing the piston and rings. I double checked the compression on the other two cylinders and I have 127psi in each and the pistons appear to be in excellent condition. This machine only has 1800 miles on it! Do you guys think I could get away with rebuilding the top end on the mag side only? What do you guys have for input? Also, why would the mag side piston have melted down? I spoke with a rep at a dealer and he said it was typical for the mag side to run lean. Is this true?
 
Tear it down and post up some pic's,,nothing's typical it happed for a
reason,something happened in that carb and you went lean in the range
somewhere, need to find it..
 
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