2000 srx piston question

well no it cant run with out coolant but from what im seeing you had other issues happening/on going before this happened, running at night temps are lower(runs leaner) and if your running on the edge jetting.....sqeek!!!

but whatever,, find your problem and go from there,yea id be pissed also :o|
 
the detonation in your case came from heat i believe, no they will not run long without antifreeze,the reason the jug stayed full is because of the leaking hose, the system works on preasure and vacum, when it gets hot presure from expanding antifreeze pushes it in jug, as it cools shrinking anti freeze sucks it out of jug, this only works on a sealed system, the jug is an expansion tank not a reserve tank
 
my guess would be it started before the light cam on, i dont know what temp the light comes on or were its located in the flow, but i believe once the center started getting hot that the steam preasure (airlock) in that cylinder made the remaining coolant by pass that cylinder, and didnt set the light until the other cylinders warmed the flow enough and depending on leak the sensor may not have had flow and was not set until area around the sensor got to that temp just judging from color of other cylinders
 
Thanks guys, going to pull that cylinder and check the crank bearing, take some closeups maybe that will help determine the cause.
Is it possible to remove just one cylinder without messing up the gasket?
Is that head still usable? going to have to revise my list to santa lol...
 
spoons said:
Thanks guys, going to pull that cylinder and check the crank bearing, take some closeups maybe that will help determine the cause.
Is it possible to remove just one cylinder without messing up the gasket?
Is that head still usable? going to have to revise my list to santa lol...
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I see signs of detonation on the center and mag and most likely on the pto but I can't see it well.

Jetting looks to be fairly safe and I would guess the burned piston is due to detonation from overheating due to the loss of coolant. If the pto piston has the same deto/peen marks the other two do, I'd replace all of them.

Straight edge the heads to see if you want to cut or replace them, look for any debris in the crank case buy washing it on it's side over a clean towel and disassemble if you find anything. The piston looks "chunked" so I'd expect you'll find pieces. If it's just been melted (make sure the piston skirt is still in tact), washing the crankcase and checking for (rotate everything a dozen times, then repeat) ANY binding might get you by.

Didn't you smell or wear any coolant?
 
Trust me on this one I have the piston and cylinder in that garage that look just the same. You cooked it from running without coolant, been there and it sucks. I cleaned up my head with a dremel and ran it without any issues. I recently bought a set of heads and plan on changing them out when I re-ring. Clean up the head put some new pistons in that are pitted or melted, put a new jug on it and let it rip. I would check the crank bearings while you have it apart. And only use OEM parts. She will rip for years to come.
 
removed the cylinders and pistons and when turning the crank I dont feel any grinding or sticking but it feels like I'm turning a servo motor I can actually count thirty incroments per revolution, is this ok?
On the top of the crank case where the cylinders sit there are four tear drop shaped pits, on mine three of the pits were dry and one was filled about a third with what looked like a mixture of oil-antfreeze does anyone have any idea what those pits are for and why I would have fluid in there?

Thanks.
 
The temp. sensor on these sleds are in the wrong location in my opinion. They are located some distance from the source of the heat, the combustion chamber. The location is fine for sensing the coolant temp. but in the case of coolant loss, there will be a considerable lag time between the loss of coolant and the sensor triggering the warming light. On other Yamaha sleds the location is much worse, for example, on the RX-1, the temp sensor is isolated by rubber hoses. You could set the engine on fire before the sensor would trigger the warning light. A friend of mine hit something in the trail which cracked his heat exchanger. He lost all of the coolant, the temp. warning light never went on, he realized something was wrong when he smelled the engine getting very hot. The temp. sensor should be in the cylinder head.
 
Yes I agree, after putting my motor back together I'm going to do some testing with temp. gauges, I'm figuring I'll install the thermo-couple somewhere on the back of the motor so the wind will not effect the readings the challenge will be determining the range and the max of course.

How about my crank question ^^^^, can somebody help me out so I can finalize my shopping list.....TY.
 
ur feeling the magnet pulls on the flywheel when it rounds,normal,the other holes you talking about your coolant passages for the case? post a pic.

i would probably pull the motor and split the case to check bearings further but that's me.
 
Here also is a pic of a piston and the head which the previous owner was nice enough to re-install for me, is this head still useable? Thanks
 

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daman said:
i would probably pull the motor and split the case to check bearings further but that's me.
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IMO:

I agree tear it appart + check/refresh it...I know what a pain! It could be worse you could be looking at rod exit wounds in the case! [ lol ! been there done that few times!]
The lower end may not be damaged but if it is contaminated with piston debree +/or the rod bearing is damaged the next time it goes down will be shortly and won't be pretty!

Now thats what I would do...but I am fanatical about things like engine rebuilds!


At a minimum:

The cases/reeds/exhaust have to be flushed + blown out with an air gun to ensure there is no contamination left. If you can see any metal at all in the crank case - it is dirty!
Once its cleaned up, visually inspect the rod especially down towards the big end , if it is blue[looks like heated metal] you will have rod bearing damage! The rod discolouration is an indication of how much heat the rod bearing was exposed to...they can't take much overheating at all and the cage fails.
If the rod is not discoloured, looks good, and feels smooth, oil it and reassemble.
I think you probably lost that cylinder because of the coolant leak = no head cooling = DETONATION, but clean those carbs and if all else is stock, run stock jetting.

JM.02c
 
what bob said....

That head could be cleaned up of any sharp edges and resued but i would look for good used that black crapy looking paint would just bug the hell outa me.

soak up that liquid in that hole it just could have gotten in ther when the jug was removed.

bad things happen when you rush a job like this.
 
spoons said:
Here also is a pic of a piston and the head which the previous owner was nice enough to re-install for me, is this head still useable? Thanks
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I would not reuse that head[although I have seen it done] .
The head has been badly overheated and all the sharp edges from the damage are "seeds" for detonation.
The damaged heads I have seen reused have been hand sanded with 400 wet to smooth the combustion chamber as best as possible, but I would not do it, or recommend it, on an SRX or any high perf application.

JM.02c
 
ok thanks, gonna have to bite the bullet on this one and pull the case and bring it to a pro, weather man calling for rain this week anyways lol....
Btw thats not a pic of the center piston which melted, thats the clutch side piston and theres no way all that metal is in the case or blew out the exhaust, that piston was re-installed like that I'm sure of it. No clue on that oil in the pit eh....?

Thanks sideshow gonna change it.
 
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spoons said:
ok thanks, gonna have to bite the bullet on this one and pull the case and bring it to a pro, weather man calling for rain this week anyways lol....
Btw thats not a pic of the center piston which melted, thats the clutch side piston and theres no way all that metal is in the case or blew out the exhaust, that piston was re-installed like that I'm sure of it. No clue on that oil in the pit eh....?

Thanks sideshow gonna change it.
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You're nearly there, all you need is parts. Sounds and looks like you're pro enough to get it done. The only specialty tool you need that I can think of at this point is a flywheel puller. Get a copy of the shop manual from daman. Split the case (make a stand out of 2X6 to rest it where the base gasket goes) and inspect like Bob says, put it together and seal it up.

Hard to believe someone would put a piston back in like that but I spoze it's possible. I have reused cylinder heads in that condition with some clean up when I had to but not on anything with more the 40 hp.
 
i have cleaned up way werse heads for people to use and they will work, but if your looking for .001 second speed time in 500 feet i would replace and make like new in other words if your just enjoying the sport clean it up, if your racing buy new one, the worsed it will do is lower the compression in that cylinder by ? just get rid of all sharp thin edges and you will be fine. just my opinion
 
Noted, if I dont get a package deal with a cylinder thats what I'll do.
could a brocken reed cause this kind of damage? gonna try and sneak into the garage today and pull the carbs, but I did notice the lower section is un-glued and is flapping open on that cylinder. Thanks, Merry x-mas to all.
 
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