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Discussion Starter #1
New to this forum but have read lots of expert advice in here so would like to see if someone could help on getting the right new piston and rings set.
Last year I bought a 1991 Trailboss 350l not running and found it to have a stuck piston and also when disassembling the crank and connecting rod bearings were completely gone. Also found that the piston was 0.20 oversized.
Since then I have had a new BRONCO connecting rod and bearings pressed in at an engine shop as well ordering some new bearings for the lower end recently.
What I am trying to determine now is------

1) what size piston and ring kit should I get and how much clearance should there be between the piston and the cylinder wall?

2) When I insert rings into the cylinder wall,how much end gap clearance should I have on each?

P.S. I will soon be honing the cylinder and will take all measurements after.
Also I saw on the downloaded Polaris manual where it has several different sets of numbers for the (91-93) trailboss (one set under the other) and just dont get why?

If you check at page 7.3 and on side scoll bar the number is 227 ---ENGINES and title 1991-93 ENGINES AND SPECIFICATIONS you can see these numbers

http://gh-ftp.com/ORV Manuals/Polar... - 1995 Polaris All Models Service Manual.pdf


So Thank you in advance for any help you can offer and hope to hear back from someone soon.....
 

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Welcome to the board!:med:
 

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ring gap .010 to .012
piston to wall clearance .004 to .005
remember to oil up the piston and put a little oil in the gas to get her broke in even with the oil injection
 

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Discussion Starter #4
Bruce thank you for the welcome and Indy thank you for the clearances help and tips. The new crank bearings and the new water pump bearing and seals should be here today or monday. Good to finally know the clearances so I can soon order the new piston and rings kit. Saw several kits online available from original to aftermarket. My neighbor who rebuilds boats and snowmobiles and says not to use wiseco. Have been looking into a Namura kit anybody have any thoughts on those or whats the best kits to use?
 

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we use wiseco kits in our trail and race sleds nothing but good
 

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Discussion Starter #6
Thanks again Indy good to know wiseco is a good choice for the machine then. I also recall the engine company owner had the same year trail boss 350 and said he could get me a wiseco kit as well. Not a bad price on it either. I saw a few OEM piston and ring sets online too but not sure if people still use them over a wiseco kit or not.
 

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Welcome to the forums!
 
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