Just ordered the kit. Now to wait.

 

I've not split a 400 so I'd rely on OPT's advice. You may need a case splitter...often the crank bearings are a pressed fit and getting the halves apart can be challenging. Not sure it's a weekend thing...really depends on how the tear-down goes and what you find. I'd test for play in the rod (up & down) before having the crank serviced...the needle bearings are incredibly durable (My son's LT80 is almost 30 years old with original rod bearing & there is no play)...however, if you find any metal in there then you really don't know what damage it's done...so if metal is found then crank work should be performed. At a minimum have the crank checked for trueness...a manual will tell you spec. I have access to a great engine building shop...to pull bearings & test crank true was $10...Heat & cold will be your helper when you put it back together...lot's of info out there to assist...

 

Case splitter's not necessary and a simple bearing separator can get the bearings off. Crank run out allowed is .001 which I was able to get with my truing stand and dial indicator with hardly any problems. As far as going into the 400 without changing the rod,no way I'd let that slide on a 13 year old machine. Some of the smaller engines may have rod bearings that can last for years,but I've been snake bit in the past on the 400 and so have many others by assuming rods felt good and just installed crank bearings only later to have one fail.After that I wouldn't guarantee just a top end on any 2 stroke. Having the right tools is the hard part,20 ton press,dial stand and indicator. Again most machine shops won't charge that much to replace the rod and true it up. Plus if he ordered the kit I linked to,it comes with the rod, lower bearing,spacer washers and crank pin.Take advantage of it and do it right.

 

So far I have followed your advice to a TV. I have ordered the exact rebuild kit you linked. I am hoping for more help as the process moves forward. I plan on removing the engine completely this weekend and getting ready for the teardown. This being my first complete rebuild, I definitely want it done right. I am unable to afford a new toy so rebuilding one to like new condition is the next best thing for me. Plus I am looking to learn a few things in the process. Thanks for all your help OPT!

 

FOT13 - I wish you the best of luck & yes, you will learn a bunch. I don't agree 100% with OPT with regards to the crank, but it most certainly wont hurt and if you have the time/budget...why not...

 

Again you take a chance. Just like this member did and dozens of people I had at the shop over a 23 year period.https://atvconnection.com/forums/pol...ng-seized.html

 

I have already purchased the entire kit. Might as well find out how it all comes apart and goes back together.

 

OPT, how would you go about splitting the case without a splitter?

 

Propane torch especially around the rear of the counter balancer. You have to take off the crank gear first. Pay attention to the dots on the gears when reassembling. Several people have just left the c/b in the outer cover,but to really do it right it's best to have the tool and pull it. Once the outer cover's off you can throw a little heat around the cases especially the clutch side that has the two crank bearings. Tapping on the ends of the crank shaft with a dead blow hammer helps in starting the case separation,plus there are a couple points you can tap with a brass hammer to get one side off. On the other side just knock the crank shaft out. Leave the bearings on the crank shaft for the machinist to remove and give him the new ones along with the rod assy to install. Again the manual can help you on tear down and assembly.

 

Or just let the machine shop do it...they have case splitters...pressed bearings can be a PITA...hopefully yours comes apart easy...