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Discussion Starter · #1 ·
Ok so my sled wont start or run. i had it running and while i was going i would feel a clunk from the track when i would give it full throttle, but if i gave it half throttle it wouldnt do that. decided to go home on the way home it died and will not start. i did notice that i went threw a full tank of gas. in less then 2 hrs. when trying to start it will almost start then before i give it gas it will die. Then after about 15 mins. of pulling it gets harder to pull. I have good compression and it is sparking on all three cylinders. how do i check the crank case seals. i heard these go bad often on these sleds? i am an auto mechanic and i am new to sleds please help me. thank you all for reading this and thank you for replying.
 

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Ok what you need to do is put the sled in a heated garage or have a heat gun to heat the block up. There is going to be bolts in the front of the crankcase take those out to see if there is any fluid that comes out. That will see if there is any issues with water or fuel that is leaking in to the crankcase. Then get it running and have a can of carb spray. When running spray around the base of the cylinders and the crankcase. Then spray behind the clutch where most of the issues are with seals. If there is nothing that you find you might have bad rings or bad crank bearings. Hope that you find the issue. If there is anymore info to give after you do that tell us and we can try and help you out. Hope for the best. If there is water in the crank get a can of fogger and fog the motor. That will help to try and save the crank bearings.
 

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Discussion Starter · #3 ·
ok, i put it in the garage and i am going to try that in the morning. A couple things i noticed one of the motor mounts was not bolted. could that have caused the clunking in the track i felt while giving it full throttle? will know more in the morning. also should i use carb cleaner to make it run or starting fluid? thank you for the advice. could it be a bad key switch?
 

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Discussion Starter · #4 ·
Ok, So this morning I tried using the carb. cleaner to get it to start. I tried just spraying into the air box and directly into the carbs. Neither ways got it to start. Then I decided to completely verify I have spark. All three cylinders are sparking. One thing I did notice in the way of leaking is the coolant seems to be seeping out from under the block between the crankcase. When I looked down the sides of the cylinders I noticed coolant kind of puddled in there.` I pulled on the clutch to see if there was any play in the crank. It didn't budge. So, I sprayed some fogging oil down the cylinders like you said and now I am letting it sit till I get back from work with my compression tester and starting fluid. As for the spark plugs, they were brand new before I took it out and they are black and extremely wet every time I pull them out. What do you think? Replies greatly appreciated. Thank you.
 

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Discussion Starter · #5 ·
So, i checked the compression. cylinder 1=145 cylinder 2=105 cylinder 3=150. after getting this reading i took the exhaust off to look inside the cylinders. The middle piston is scored has a couple pock marks on the rings and a little below the rings and scratches on the skirt. It looks like coolant is leaking on the gasket between the crank and the cylinder wall on the two outer blocks. are those gaskets still good? because it has good compression? do i need to rebuild the middle cylinder piston and piston rings? any ideas would be great and super appreciated. what could cause the middle to go but not the two outside
 

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A good place to get pistons for the 650 motor is a company called LA Sleeve. They make a OEM style piston up to .080 over for that motor at a decent price. http://www.lasleeve.com/master.html
 

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Discussion Starter · #7 ·
so i took the center cylinder apart today. the whole front side of this piston is scored and the rings dont even stick out. so i need to replace the piston. and the rings. the connecting rod is bronze and moves freely without any binding. how do i get the piston pin off the connecting rod. i removed the clip. do i need to press it out like you would for a vehicle? the cylinder walls have no gouges just a little color change from a dull color to shiny. all smooth. do i still need to replace it or is it ok? just hone it out and it be ok?also should i replace all the gaskets on all three cylinders or just the one? because i am buying a top end gasket kit. with the piston and rings tomorrow. do i have to reset the carbs if so does anyone have the specs? thanks for the help.
 

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Discussion Starter · #8 ·
took the whole motor apart today and found out that both my other cyliunders are screwed. the are cracked at the skirt of the pistons. what causes the skirts to break. also i bout spi 65C pistons and the whole gasket kit. are those good pistons besides honeing is there anything else i need to do? crank is good.
 

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If the piston skirts are cracked that usually means you have too much cylinder to piston clearance. Your best bet is to bore it over .010
 

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Discussion Starter · #10 ·
On the cylinders starting from the cluch side to the mag side. Cylinder 1- has a large crack on the left side where the part where the pin goes and the skirt begin. also there are small scrapes on what i would say 4 corners if the piston had corners. cylinder 2- the exhaust side is scored to hell. rings dont even stick out. also has two other scored spots. on opposite sides. cylinder 3
- this cylinder had a small crack in the piston no other scored spots on the piston.
 

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Discussion Starter · #12 ·
well i put oil and gas and the coolant. about thirty mins. of pulling it started. started out slow wouldnt run very long then got better and better. compression in all three cylinder 145 psi. not it runs but the idle is about 2000 rpm. do i need to adjust the needle and seats? i already tried to adjust idle air screw have it 1 1/4 turns on each. also how long should the break in period be?

that was after i got 3 spi 65 c pistons and a gasket kit. rebuilt it from crank up. honed cylinders. forgot that in the last blirp
 
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