MS 310 Rebuild

[Wood Chopper]

First of all great site you guys have here. I just rebuilt a ms 310 for my dad that was getting tired with an aftermarket 390 kit from Northwood saw crank bearings, carb rebuild etc. The piston and rings were very difficult to install I thought. I am new to spinning wrenches on our chainsaws but have rebuilt many other 2 stroke engines mainly dirt bikes. The manual says use a spring compressor but the start of the actual cylinder is so far away from the clam shell mating surface that I am not sure how that would work. Is the cylinder taper supposed to squeeze the rings as I push it in. The saw pulls over hard so I am sure the rings are not seated right. It did fire up but then quit. So back apart she comes. The kit seemed to be made well. Has anybody else had this problem with this kit.


On a positive note I did the muffler mod to my 310 last week and couldn't be happier. Sounds a little meaner as well.

 

[chainsawman2011]

for starters I always use caber rings. as far as difficulty getting the piston and rings in the cylinder it can be tricky but if the bottom of the cylinder tapper is tapered right u just put the rings on the piston and the cylinder drops right on sometimes you have to lightly persued the rings with a small flat screwdriver.

 

[chainsawman2011]

for starters I always use caber rings. as far as difficulty getting the piston and rings in the cylinder it can be tricky but if the bottom of the cylinder tapper is tapered right u just put the rings on the piston and the cylinder drops right on sometimes you have to lightly persued the rings with a small flat screwdriver.

 

[fearofpavement]

If the saw was hard to turn over, starting it was the wrong thing to do. You may have damaged the rings, cylinder, piston or all of the above. Pull it back apart and make sure everything is ok. (it won't take nearly as long to disassemble/assemble the second time)
Make sure to lube the piston and cylinder bore. I just wipe some grease on them but a little oil works too. Saw will smoke like crazy for about one minute but then all's good.

 

[Wood Chopper]

Thanks for the replies guys you are both right and I'm an idiot. I knew something was not quite right I should have stepped back and looked closer. I put the rings in upside down. Its been a while since wrenching apparently and went too fast as everything else was going well.

On Sunday tore everything back down in 30 minutes like you said and took the rings off one broke due to i'm sure too much pressure. Brand new caber rings installed last night 3 pulls and she is ready to chew wood. Had too mess around with low idle circuit. Let it run and get warm for a minute and shut her down. Did that a few more times and she starts 1 pull and idles nice.

Thanks guys. How long should I take it easy on the saw 1 tank?

 

[singletrack100]

Woodchopper, I think most here will say tune it and run it. Our saws are tuned in the cut at full throttle. They're rich out of the cut, and our carbs don't have accelerator pumps, cruise and power circuits for in-between stuff like auto carbs. After a few tanks recheck your tune just to be safe. Enjoy!

Duane