Explaining my problem.
Last spring I was riding with some buds. While doing a slow, whooped out section of trail and being a bit rusty on the throttle I suddenly heard a metallic rattle from the engine. It didn't last too long, but maybe 15-25 seconds. In that time I couldn't determine it's cause.
The day was warmer, and snow was that spring time set-up where it had some fresh on top, but a rotting base. I've personally never ran this late in the year.
Either way, after that incident I noticed the engine to be less responsive, poor at idle, slightly off with sound, and lacking top end. At times almost sounding like it was miss-firing. The strange thing is at times I swear it was running good for a few seconds.
I originally figured I did it in. Either piston skirt broke, famous seal blow-out, or it digested a chunk of my reed valve.
Not wanting to hold up the group I pampered it the rest of the day and rode it out... never a fun thing when you know the engine isn't running well.
The sled has around 3500-4000km's. Overall, from my ownership ridden relatively easy compared to some. I don't seem to need to use WOT throttle to do what many others do, so I just ride it easy.
So, since the weather has cooled a few days ago I decided to dig into it. I checked the following:
1) Reed valves are in perfect shape. No gap, no chips, no missing screws/rivets, nothing.
2) Carb boots look as good as day one.
3) RAVE's were pretty clean and in good operating condition.
4) Last spring the piston's compression checked at ~140 and ~150. I know people either say 10lbs between pistons or 10% is rebuild time. Either way the one would go higher but seemed to require more aggressive pulls. It's the stator side piston.
5) Spark plugs appeared to differ. One being slightly black and the other slightly light. I'll have to dig those out for more detail, this is recalling info from last spring and I've worked on a few engines since then..
6) Pressure checked engine tonight and it checked good with and without the cap. Held 5psi for a good while.
So what could the problem have been? Was the metallic sound I heard a missing bolt/spark plug/kidney from the bellows beneath the engine coughed up by a rough section of trail and the performance difference from warm weather and power sucking snow? Was it a piston skirt been eaten and spit out? Was it electronic somehow and the noise was in my head? Is my stator gone and it was just sucking ass from miss-firing and poor spark?
Jetting on the sled is fairly standard with exception to the pilot. It's still the 17.5 and not 20 from the apparent recall or "complaint change".
My next step is to take the head cover off and check for cylinder and piston damage. If nothing found I figure I might order some pistons and do the top end... It just sucks because this year I'm house poor and hoping to save as much costs as possible.
Let me know what you think. Maybe somebody has gone through a similar experience? These sleds are common so here's to hoping...
Last spring I was riding with some buds. While doing a slow, whooped out section of trail and being a bit rusty on the throttle I suddenly heard a metallic rattle from the engine. It didn't last too long, but maybe 15-25 seconds. In that time I couldn't determine it's cause.
The day was warmer, and snow was that spring time set-up where it had some fresh on top, but a rotting base. I've personally never ran this late in the year.
Either way, after that incident I noticed the engine to be less responsive, poor at idle, slightly off with sound, and lacking top end. At times almost sounding like it was miss-firing. The strange thing is at times I swear it was running good for a few seconds.
I originally figured I did it in. Either piston skirt broke, famous seal blow-out, or it digested a chunk of my reed valve.
Not wanting to hold up the group I pampered it the rest of the day and rode it out... never a fun thing when you know the engine isn't running well.
The sled has around 3500-4000km's. Overall, from my ownership ridden relatively easy compared to some. I don't seem to need to use WOT throttle to do what many others do, so I just ride it easy.
So, since the weather has cooled a few days ago I decided to dig into it. I checked the following:
1) Reed valves are in perfect shape. No gap, no chips, no missing screws/rivets, nothing.
2) Carb boots look as good as day one.
3) RAVE's were pretty clean and in good operating condition.
4) Last spring the piston's compression checked at ~140 and ~150. I know people either say 10lbs between pistons or 10% is rebuild time. Either way the one would go higher but seemed to require more aggressive pulls. It's the stator side piston.
5) Spark plugs appeared to differ. One being slightly black and the other slightly light. I'll have to dig those out for more detail, this is recalling info from last spring and I've worked on a few engines since then..
6) Pressure checked engine tonight and it checked good with and without the cap. Held 5psi for a good while.
So what could the problem have been? Was the metallic sound I heard a missing bolt/spark plug/kidney from the bellows beneath the engine coughed up by a rough section of trail and the performance difference from warm weather and power sucking snow? Was it a piston skirt been eaten and spit out? Was it electronic somehow and the noise was in my head? Is my stator gone and it was just sucking ass from miss-firing and poor spark?
Jetting on the sled is fairly standard with exception to the pilot. It's still the 17.5 and not 20 from the apparent recall or "complaint change".
My next step is to take the head cover off and check for cylinder and piston damage. If nothing found I figure I might order some pistons and do the top end... It just sucks because this year I'm house poor and hoping to save as much costs as possible.
Let me know what you think. Maybe somebody has gone through a similar experience? These sleds are common so here's to hoping...
