fortress
New member
fortress
New member
9801srx
Member
looks like you burned the top exhaust edge off the piston for whatever reason ,maybe carb froze up or pluged main jet . with continued use the heat gets to the top ring and it eventuly hooks the exhaust port breaks up and smashes up the head and usually the cyl. i had this happen before and didn't even know anything was going on because the bottom ring was still sealing until the top ring hooked the port.
woolyviper
New member
make sure you figure out the cause before you start running it again - or you might do it again.
daman
New member
Wow not pretty....
look's like some nasty lean burn down, did you ever check wash or pug color?
look's like some nasty lean burn down, did you ever check wash or pug color?
daman said:
Daman hit on the head...lean burn...what cylinder was that again...when you tear into that carb, make sure it is jetted to specs & the needle clip are in the proper position...ok, lets keep this simple...two things can cause a lean out, a out of tune carb (jetted different, mixed up jets from another carb, dirt/gum - lack of pre-season clean) or a air leak (more air getting to that cylinder then fuel -out of mixture caused by crank seal leak, base leak, intake boot leak)...if snow was ingested from the air box it would of seized right up quickly or have the tell tell signs of 4 corner seizure common in mountain sleds...other will chime in & put up a clearer explanation and what really happened...& hopefully all will point you in a proper direction to fix that sled up...the only question I have is there any debris in the bottom of that engine...to pull the engine & clean it up or rebuild from there...I know what I would do...keep us post fortress, keep that chin up too, it ain't that bad...how's the rod & bearings look...
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daman
New member
^^good advice
fortress
New member
hi guys! i did not open the carbs yet
i will try to do this this week..
the carbs are stock .. its probably more a lack of pre-season cleaning
i dont see debris in the crank base...
i will try to do this this week..
the carbs are stock .. its probably more a lack of pre-season cleaning
i dont see debris in the crank base...
daman
New member
post the sizes and position of all jets and needles,,fortress said:
YAMAHIZAL700
New member
as the blues said which cylinder was it? If its the pto side most def. look towards the crank seal. i had the same problem last season when i took the old seal out sure enought it was torn. the thing that sucked is it took me a piston/cylinder before i finally figured it out!
woolyviper
New member
if you didn't change anything - i would look for a plugged carb, or an airleak - either a crank seal or an exhaust leak.
SpartaSXr
Member
Engine
With that type of damage to the piston ask yourself where the debris went ??? It went into the crank ! Sounds like a big problem but its not that bad. Pull the motor and pull the case apart. Take the crank to a parts cleaning tank and flush the debris out of the bearings. You will be astonished with the amount of shavings etc you will find in there. After the bearings and case are clean, reaassemble it. CAUTION DO NOT use compressed air to spin the bearings on the crank ! You can blow the fluid out but do not rotate the bearings with air. It will damage the roller bearings. When all is clean, lube the bearings with assembly oil and install new seals. Then make sure the carbs are clean and jetted correctly. You will be happy with the results. Do the job right the first time. I am sure there are others out there who will chime in. Good luck and be sure to ask if you dont know. You should be back on the snow for around $ 400.00 with you doing the labor.
With that type of damage to the piston ask yourself where the debris went ??? It went into the crank ! Sounds like a big problem but its not that bad. Pull the motor and pull the case apart. Take the crank to a parts cleaning tank and flush the debris out of the bearings. You will be astonished with the amount of shavings etc you will find in there. After the bearings and case are clean, reaassemble it. CAUTION DO NOT use compressed air to spin the bearings on the crank ! You can blow the fluid out but do not rotate the bearings with air. It will damage the roller bearings. When all is clean, lube the bearings with assembly oil and install new seals. Then make sure the carbs are clean and jetted correctly. You will be happy with the results. Do the job right the first time. I am sure there are others out there who will chime in. Good luck and be sure to ask if you dont know. You should be back on the snow for around $ 400.00 with you doing the labor.
YAMAHIZAL700
New member
AMEN!SpartaSXr said:
great advice
fortress
New member
if it would be an air leak problem, i would have see some overrev with my rpm??
fortress
New member
by the way, the crank seal are new from last winter, so, i dont think they have something wrong with it
SpartaSXr
Member
Seals
No you would not see an over-rev. If the crank seals were replaced last season and the sled was running OK then you have led me to believe the carbs were the problem. Did the sled get summerized last fall ? With the piston melted that way toward the exhaust, it was lean when it went. Either an air leak or lack of fuel. The way you described the lack of power in the earlier post it appears to be carb / fuel related.
No you would not see an over-rev. If the crank seals were replaced last season and the sled was running OK then you have led me to believe the carbs were the problem. Did the sled get summerized last fall ? With the piston melted that way toward the exhaust, it was lean when it went. Either an air leak or lack of fuel. The way you described the lack of power in the earlier post it appears to be carb / fuel related.
is the connecting rod and wrist pin bearings intact and tight?
fortress
New member
SpartaSXr said:
well humm no, the sled did not get summerized last fall.. I was frustrated with all the problem with this sled that i didnt take the time to "summerize" the sled
my faultMRviper, the connecting rod, well i'M not an expert and add the fact that i did not remove the piston ( i cant remove that damn piston pin) , with what i saw, the connecting rod seems ok to me.. I dont see damage where it connect to the crank
Fortress, stuff rags under that piston...I sometimes have great success with using a bladed screw driver & go around the opening of the piston pin area shaving off piston material...I used (for the first time) a threaded rod with washers (the washer smaller than the pin) & nut at one end, past it threw the pin to the other side, place a large socket (bigger than the pin) added a washer, nut & bent the threaded rod to make a handle (10" up) and viola, you have a home made press/puller...OR...you can get them at any auto store, from $25 to $35 bucks...if you think its binding on the rod, then stop, take it apart & use a pair of visegrips & twist it out...good luck...what ever you do DO NOT HIT WITH HAMMER...got it...
fortress
New member
theblues said:
well humm, i did already try with an hammer
but i wasnt smashing real hard, and did stop it when i did saw that nothing happenedi should have thinking about the rod
but i don't think i have made some damage to it.. I think i will just wait my friend for him to complete the job...