What's up guys new here I have a 2002 Polaris scrambler 400 2x4 and I just did a top end rebuild new piston, rings and gasket also got the skirt bored out and changed the stator and new spark plug. also rebuild the carburetor as well. I had it sitting for a few months and until I had the time to do the top end now that I replaced all those components it makes like a knocking noise that it didn't make when I first bought it. it has oil in the counter balancer and my premix is 32:1. It starts with no problem every thing works its just that noise and when I put it on reverse it will try to shut off when I let the front break handle go it will do that some times I'm just trying to get help on the problems so I can go ride this week end thanks guys.

 

Dying in reverse can usually be taken care of by removing the black wire from the reverse limiter module. Item #28 in the parts break down. The knocking could be a rod or crank bearing if you didn't check for any up and down play on the rod before you did the top end.Plus on the 400 you have to make sure you bled the 10mm bolt on top of the head to remove any trapped air or this engine can over heat quickly.The new piston can put more pressure on the bottom end and you may hear noises that you didn't hear before. I've had this happen several times at the shop when people just did top ends and didn't check out lower ends carefully.I had to end up tearing off the new top end and rebuilding the bottom end also. Hope this isn't what's happening but sounds like it.

 

Thanks I will try to do those things and what all do I need to replace the bearings I can still use the top end gaskets and piston right. The only thing I have to change is the gaskets for both side engine covers right. And what is better a gasket or that stuff that's says instant high heat gasket maker thanks again

 

Also what all do I need to change just the rod and the bearing or other bearings as well

 

You can save the piston,but you need a rod kit installed, crank bearings,water pump bearing and seals and gaskets need to be replaced along with a new base and head gasket.Can't reuse the old ones without possible leaking problems. The engine is complicated and no sense trying to take short cuts on this. Polaris Scrambler 400, 1995-2002, Connecting Rod Kit - 3084153 | eBay
Polaris ATV 400 & 400L Complete Engine Gasket Bearing & Oil Seal Rebuild Kit | eBay A manual is needed especially on the critical parts.2002 Polaris Sportsman 400 Service Manual PDF Download

 

Can I still use the top end gasket I have on them there only like a week old I just recently did the top end like a week ago and I just started it and and when I heard that noise I turn it off and never started it. And I didn't put any silicon on them the only thing I put silicon was on the water pump gasket and the gasket that goes behind the stator. I know I have to get new ones for those.

 

Once a metal head gasket raised area or squish band as it's called has been compressed,once you remove the gasket it usually wont seal right again. I wouldn't trust a base gasket either. Not worth the aggravation to have to tear one down again to replace leaking gaskets.