Need advice for rebuilding

[Blown2001rm250]

I have a 2001 RM250 that I need some advice with. I was riding on the weekend and seized the motor. What i thought was going to be a simple top end job has since turned messy. I pulled the top end off and found that the piston had broken apart and some small pieces probably fell into the bottom end. Also, the bottom end is seized. I am pretty mechanically inclined, but I have never split a case. Also, I removed the engine from the frame without loosening the big clutch nut. Could someone please give me an idea(s) as to what I should expect or need to do this big of a job. I've ordered bearings and gaskets and would like to split the case as soon as possible as there is races the next two weekends. Thanks in advance!!!

[D tom]

I have redone many, It helps to have a large clean organised work platform.and a good manual.If you are lucky the pieces didn't damage the crank.

[Fluffyhead]

Well since I just rebuilt a 2002 RM 250 from soup to nuts - I would like to help with the essentials. First, grab a full blown Clymer manual off of Ebay - it's $25-28 well spent. The tools to score at Sears (Craftsman sockets) and what needs to be ordered from a motorcycle store follow:
I used Rocky Mountain MX/ATV in Colorado (online site is easy to use) and their 'Tusk' brand tools worked very well in my hands. You need a clutch holding tool (it doubles as a flywheel holder). It grabs the outer clutch basket and prevents rotation when you try to back off that big clutch nut. My 2002 had a 30mm size nut, fyi. I got a Craftsman 1/2" socket end breaking bar for leverage. Those nuts are on like a mother!&*$er (self edited). I recommend the Tusk: Flywheel puller; the Crankshaft puller; and the case splitting tool, as well. No financial interest - they worked well for me and on YouTube there is a part 1, 2, & 3 series on lower end case splitting and rebuilding done by Eric at RockyMt ATV. They are invaluable and a Youtube search away. You will also need a long, deep 12mm socket to engage the shift detente nut. You will also need some medium strength LocTite in certain sites. I spent $16 at an Autozone for an impact screw driver. Seered into my memory banks as major pains to back out were the 2 Phillips head screws retaining the centrifugal exhaust valve assembly on the clutch side lower case and the equal sized Phillips screws retaining the shift detente also on the clutch side.
In splitting the cases the most intimidating thing for me was the interaction of the main and counter shafts, their circlips and thrust washers being in the right place on rebuilding the cases, and the 3 gear fork lifters and the shift drum/barrel interaction coming together correctly. The Youtube video and the manual make it look easy - it is not easy. Look closely and or digi photograph as you disassemble. If their is broken metal hardware in the lower end cases, you will need mineral spirits and a clean plastic basin in which to wash the parts. Relube with a little transmission oil of choice and store in quart or gallon Ziplock baggies to keep things clean and organized before the reassembly. Fresh gaskets are key as are nice new bearings. If you are redoing the crank bearings, you need flywheel and clutch side crank seals as well.
I would be happy to help more. BTW, Welcome to ATM - there are some very helpful and knowledgable folks on this site. Feel free to ask away - and digiphotos are always a plus.

Good luck/Peace,
Sean

[Blown2001rm250]

Thanks for the info it was very helpful. how will i know if the crank is damaged? it has very minor abrasions but seems to be fine. Is the mineral spirits an essential participant or could i wash the parts with something more common? thanks again!!

[Spikester]

Look for up and down movement of the rod on the crankshaft, if you can detect any play it most likely needs a rod. before you remove the crank, see if it has any play in it, does it float in and out when you pull on it. you can spin the rod bearings and listen for excess noise, but be sure the bearing has oil in it, a dry bearing will roar. I found rod kits and crank bearing kits with new seals on ebay for a good price for my '97 RM250. mineral spirits can be bought at lowes in the paint department and is a lot safer than gas for cleanup, kerosine will work too. A inpact wrench will break the clutch bolt loose if you have one, no clutch holder needed.