Going to try an engine tear down RD250

[pdxjim]

I have good luck breaking the work down into sections, all the parts go into gallon or sandwich size ziploc bags to stay together and stay clean.

Motor mounts and everything that comes off to get the engine out of the frame goes into a box or a bag.  Kickstarter, shift linkages, motor mounts, etc.

Next is all the intake stuff, heads, cylinders, etc ... and the sidecovers and sidecover bolts.

All the outer stuff off the clutch side into a bag, and the same with the ignition side stuff.  Engine case bolts go into a small bag together.

I do it this way because of my work schedule.  It way take me a week to get the engine apart working 20-30minutes a night, a few nights a week.  Then it might sit for a month while I gather the necessary parts, machine work, etc.

I also always replace the worn out JIS/phillips/cheese heads with cap head allens for ease of disassembly next time.

[Ws76133]

Ok, where do I find the #2 & #3 JIS screw bits?

[teazer]

There are guys here that can answer that.  I just use a phillips or a drill bit because I throw the stock cheese heads into a box to be recycled, and then replace them all with hex head Ti or Stainless or Aluminum screws.

[Czakky]

Ok, where do I find the #2 & #3 JIS screw bits?

Amazon...

[m in sc]

look for 'vessel' brand jis cross head drivers. 

[Robert58]

I had to bag and tag to keep me organized and sane , many , many pics, the Haynes manual was very useful and impact ( air or electric) on crank, clutch and drive nut made life easy and put  less stress on tranny . Spent a lot of time carefuly cleaning case mating surfaces with razor blades , alcohol and scuff pads, then used Threebond to seal it. . Also made a leak down test kit which by using found several leaks on manifolds, but was able to seal and held 6 psig for like an hour.
Good luck , I think working on bikes is as much fun as riding them     

[quocle603]

Vessel 12$ screwdriver from Amazon was a great investment

[NYSingh]

For me, this "Ed's 350 Engine Rebuild" thread proved to be immensely useful:
http://www.aircooledrdclub.com/smf/index.php?topic=25398.0

Also make frequent use of the Yamaha Workshop Manual, Yamaha Parts Catalog (for diagrams) and Haynes manual (and this forum, obviously).

As others said, frequent photos and/or video and well-labeled ziplocs help a lot.  Get a good ft-lb and in-lb torque wrench.  Replacing bolts with Allen head versions when re-assembling is a good idea (they have kits on economycycle.com and hvccycle.com).  As you go along, keep a detailed inventory of seals/gaskets/other bits that need to be replaced.  I did it piece meal and lost a lot of time and money ordering 1-2 pieces at a time because of lack of planning (every time you pay $9 shipping for a $4 part from partzilla.com or boats.net, a piece of your soul dies).  Buy OEM if at all possible.  Also, for replacement hardware for which OEM is hard to come by, learn how to read the part numbers from the parts catalog to get the proper size/length: http://www.2strokeworld.net/forum/index.php?topic=324.0

Have fun!

[oldguyRD1964]

Hello group, I'm back in LA I think I will try part 1 of taking the engine out. However, I have a Haynes manual and noticed a few things.
1. removing the pistons and circlips: the manual states "remove and discard", does that mean the circlips and the piston gudgeon pins? should I replace the rings?
2. clutch: how big is the locknut, and from another post states replacing the clutch plates with yz250 works but does anyone know the year or part #? should I replace the springs and the metal parts as well? would yz250 work as well?
3. gear change: the manual mentions two spring loaded pawls need to be separated, is the spring tension strong? I had double thumb surgery so I need an alternate method if you have any ideas.
4. The final drive lock nut: wondering if anyone knows the size of this, it looks larger than 24mm which is my max. is it left handed or normal right handed.
5. reassembly: I see a curious photo and the caption says crankshaft will not seat unless knock pins locate... I see the picture but not understanding this. Does this caption mean I need to have the knock pin in the position of the photo which is just above the case or does that mean there's a slot in the crank case where I have to place the crank.

From viewing this manual this is one undertaking that looks tough, I know you've all said it's easy-ish I sure hope so. It's freaking me out looks like 500 or more tiny parts.
One last thing: I don't have a bench or work place I am thinking about making a makeshift work bench like area but the space is really small what would be the smallest area I could do this seal replacement. Thank you for all your comments and notes...