Radar64
New member
I've been nosing around here for a few years, but this is my first post, so be gentle.
I put about 300 miles on my 98 SRX a few weekends ago in Northern Wisconsin. Somewhere around the 200 mile mark I noticed a loss of power on top end that would come and go. The bottom end seemed normal up to about 70mph, then it would just kind of flatten out and not get above 75-80. A little later everything would work fine again and I could easily hit 100. At the end of the trip, as I was nearing the cabin and planning to pack up for the trip home, it began running even worse - lack of power. When I parked it I saw smoke from just above the right ski. Upon closer examination, the belly pan plastic was melting right under where the center cylinder pipe lays. I put a bit of snow on each of the pipes and the center cylinder pipe was noticeably hotter than the other two.
I loaded her up about 30 minutes later (still started as easy as normal and drove on to the trailer) and headed home.
I finally got around to looking at the sled today and found the center cylinder plug had a bent ground electrode to where it was actually touching the center electrode. Looking in the sparkplug hole, I can see a few small marks on the piston where it looks like something may have been rolling around in there. No large gouges or even scratches can be seen though. Nothing catastrophic-looking, but I am just seeing what I can looking through that small hole.
I plan to go through the power valves next time I have some free time. Then maybe open up the cylinder. I just didn't have time today.
I am not a mechanic. I can work on just about anything that is outside of the engine, but I have always stopped shy of the engine.
Any thoughts or guidance before I crack this open?
I put about 300 miles on my 98 SRX a few weekends ago in Northern Wisconsin. Somewhere around the 200 mile mark I noticed a loss of power on top end that would come and go. The bottom end seemed normal up to about 70mph, then it would just kind of flatten out and not get above 75-80. A little later everything would work fine again and I could easily hit 100. At the end of the trip, as I was nearing the cabin and planning to pack up for the trip home, it began running even worse - lack of power. When I parked it I saw smoke from just above the right ski. Upon closer examination, the belly pan plastic was melting right under where the center cylinder pipe lays. I put a bit of snow on each of the pipes and the center cylinder pipe was noticeably hotter than the other two.
I loaded her up about 30 minutes later (still started as easy as normal and drove on to the trailer) and headed home.
I finally got around to looking at the sled today and found the center cylinder plug had a bent ground electrode to where it was actually touching the center electrode. Looking in the sparkplug hole, I can see a few small marks on the piston where it looks like something may have been rolling around in there. No large gouges or even scratches can be seen though. Nothing catastrophic-looking, but I am just seeing what I can looking through that small hole.
I plan to go through the power valves next time I have some free time. Then maybe open up the cylinder. I just didn't have time today.
I am not a mechanic. I can work on just about anything that is outside of the engine, but I have always stopped shy of the engine.
Any thoughts or guidance before I crack this open?
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super1c
Super Moderator
No doubt you have to take top end apart to see what's going on. Do not run sled anymore till you know what's up to prevent further damage. That center cylinder sounds like it got really hot.
Pull the cylinders off and post pics of pistons. We can tell you where to start looking for the cause. Or, if I have time, I could swing by on my way home as I work in Hartford. Good luck
This might be a dumb question but why would it get so hot when its not even firing on that cyl or do you think gap closed right at the last second of running?
I'm guessing it ran lean from dirty carbs, then melted exhaust side of piston, until a small chunk of piston or ring let go, bounced around for a little while, closing plug gap. Just a theory .......
Radar64
New member
Thanks for the input guys. I will get to the pistons and follow up with pix and any new details. SSRRXX, thank you for the offer. I just might reach out to you, depending on what I find.
Devilin AblueDress!
New member
Sounds good in theory but looking at plugs it looks like it was pig rich....pics of pistons will tell the next chapter.
Good point, I didn't even notice.
Radar64
New member
I removed the heads tonight, the results are shown in the pictures. Along with the destruction of the center cylinder, cylinder #3's piston head is noticeably blacker than #1. More info: #1 and #2 powervalves slid right out. #3 powervalve is stuck.
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Too lean on the centre, melted it. Looks like the PTO side was starting to go that way too.
Probably because the carbs are dirty but could be bad adjustment, bad fuel, too much air.
Get a bud to help
Looks like you need 2 new pistons, centre and PTO (clutch side).
There may be, and looks like probably is, debris in the case from the melted piston.. Take the engine apart, clean out the deris from the bad piston.
Check the cylinders for scratches, nicks, and spots were the nikasil might have worn. Replace if needed. That centre one might need to be replaced.
Check the reed petals, make sure they are not chipped, cracked, and still seal to the cage.
Clean and adjust the carbs, clean power valves.
Check the carb boots for cracks. Take them off and squeeze them around the bends, the cracks will show themselves.
Make sure your air box isnt gutted, still has all the parts it should have.
Probably because the carbs are dirty but could be bad adjustment, bad fuel, too much air.
Get a bud to help
Looks like you need 2 new pistons, centre and PTO (clutch side).
There may be, and looks like probably is, debris in the case from the melted piston.. Take the engine apart, clean out the deris from the bad piston.
Check the cylinders for scratches, nicks, and spots were the nikasil might have worn. Replace if needed. That centre one might need to be replaced.
Check the reed petals, make sure they are not chipped, cracked, and still seal to the cage.
Clean and adjust the carbs, clean power valves.
Check the carb boots for cracks. Take them off and squeeze them around the bends, the cracks will show themselves.
Make sure your air box isnt gutted, still has all the parts it should have.