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13 BD pro top end/build

S

sdstroker

New member
Nov 17, 2013
58
2
8
Picked up a 13 pro 800 163 3" with 1600 miles on it. Has a boondocker gtx 2860 with tial and ebc controller. Initial problem was hard starting. Took at least 10 to 15 pulls to get it going. Once started for the day it was one pull. Also had a slight low end bog that I had to sometimes feather through. I ride 8k plus, 100% av gas and 10 psi boost. Done for the season, I started taking the sled apart. Noticed alot of the exhaust Springs were very easy to take off and stretched. Also noticed the spark plugs were a bit snugger then finger tight.
Did a compression test and 125 psi @ 1200 elevation on both cylinders. Next I did a leak down test and found the wye pipe gasket leaking slightly. Put some silicone on it and re tried the leak down test and passed. Continueing on I pulled the reeds. Found one peddle was chipped at the very end, rest looked good. Pulled the head off and couldn't believe the piston to wall clearance (. 020 front to back and .016 side to side). Cylinders and pistons look normal to me for the miles.

So I'll be pulling the engine sometime soon and putting new pistons in. Do you guys think I can get by with 15 pistons and a hone to clear up the slop or do the indy Dan replacement? Also thinking about going with the v force 3r reeds. Would it be beneficial to delete the thermostat?
Few other questions are whether to go with boondocker exhaust Springs or just get new stocker Springs.
Going to throw the green/white exhaust valve Springs, Tony's clutching and sending the primary to indy Dan for machining and shimming for lighting weights.
Any other suggestions while the engine is out would be great!
 
T
Apr 17, 2010
78
15
8
The low end bog issues you were having is more then likely from the exhaust leaks, if those are the stock pistons still its time for new ones. There will be alot more clearance at the top of the piston. Proper measuring is down at the skirts about 3/8 from the bottom. If you have .020 at the top then your gunna be less at the skirt. Your prob at .010 maybe more which is way loose. I run wossner pistons in my sled and they measure out to be .005 piston to cylinder clearance. They are forged pistons though. If your to run the new HO pistons you wont have to do much more then measure your cylinder and give them a light hone with the proper hone stones and you should be fine. Check ring gaps as well. .019 i think they need to be. As far as a thermostat delete i think its a bad idea.... ive never had a issue and i run forged pistons. Just make sure its warm before going..The springs i would just buy the factory springs and double them up.
 
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Snowmow

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Mar 20, 2011
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Gillette, Wyoming
Id go back with what worked well for 1600 miles, hone cyl, new Polaris Pistons, Polaris reeds, exhaust donuts and springs sometimes it's better to have a little extra piston to cyl beings its boosted. Carl's cycle built my sled. They removed the thermostat, never had a problem in 1500 miles. I did top end, reeds, fuel filter and spark plugs, exhaust donuts and springs before this season. Cylinders and pitons looked great, still had 120psi compression.
 
S

sdstroker

New member
Nov 17, 2013
58
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8
Thanks for the replies! Do you just remove the thermostat all together? I'm new to the polaris side coming off a 07 skidoo which never had a thermostat either. I thought I read the engine starts to loose power after 125*. Is there a good online place to order oem parts?
 
Last edited:

Snowmow

Well-known member
Lifetime Membership
Mar 20, 2011
28,030
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Gillette, Wyoming
Thanks for the replies! Do you just remove the thermostat all together? I'm new to the polaris side coming off a 07 skidoo which never had a thermostat either. I thought I read the engine starts to loose power after 125*. Is there a good online place to order oem parts?



Yep. Just remove it. I know some don't agree with doing it. But it sure works well on mine. I like ordering from Carl's. Or Oregon trail sports.
 
S

sdstroker

New member
Nov 17, 2013
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So the new HO pistons are they way to go? Anything else I should do while I'm in there? Turn the oil pump up?
 
S

Spaarky

Well-known member
Oct 5, 2001
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Chester, SD
I would run the TRS thermostat kit or similar. It's cheap insurance. What happens when the cold water from your tunnel slams into the warm motor. The Doo style bipass runs cool and is safe.

Have the cylinders nic'd into specs and run Axys pistons.
 
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