If you are into nitro engines, sooner or later you will end up opening them.  Typically this is due to bearings going bad, or due to over-heating on too lean runs (with pistons getting holes in them).

In any case, it is good to know how to open up the engine, and put it back together. Here are some videos that shows the whole procedure.

Part 1:



Part 2:

Three Cheers for the nice Video tutorial.

nice video  . it really hekps!

+1!

Does this get included here?

http://tech.flygsw.org/os91overhaul.htm

Very useful and important stuff.
Even if one is not keen on changing bearing and components- it is  essential to be able to properly clean an engine that has been buried in mud.
It has happened to every  flyer ( who is truthful and has flown enough).
One should be able to take the carb, head and backplate off safely. and reassemble the same.
regards
Avijit

Hi,
Using allen keys or screwdriver( depending on engine) remove backplate, carb and engine head +glowplug from engine block.
Once you have removed back plate,  you need to remove the sleeve or piston liner from the engine block. This can be difficult especially with a gummed engine. So, you have 2 choices, the edge of the sleeve should just be sticking up when the head is off. So, gently nip this extrusion up in a vice and wiggle and pull the block to loosen it. If this does not work, turn the engine so that you can see the con rod from where you removed the back plate. Using a pair of need pliers (i recommend wrapping with tape to avoid scratching the walls) put the tip to the liner and using the outer wall of the block as leverage press down and out the liner should pop!
Then the piston should flop around, simply slide off the con rod and its free!
Now, the bearings, heat the block to 150 deg c in your oven. Leaev for about 8 minutes until all heat seeps in. Now, holding the block with a glove gegntly tap the end where the back plate was removed against a flat surface (ply wood scrap piece is good) and the rear bearing should fall out. Now be very careful and put the crank shaft against the ply wood piece and GENTLY press down to ensure you dont bend it!!! If you have a vice please put it in with the back flat against one jaw and the crankshaft against the other. Gently tighten the vice and teh shaft will loosen enough for you to pull it out. 
Now you will have both front and rear bearings free. Either buy new ones or use degreaser to clean bearings and then re-lubricate.
Then you are free to use the reverse procedure and reinstall bearings and crank shaft!
P.S if you have a jammed carb, please remove all screws, rubber and plastic (basically all non metal things) and heat to 150 deg c in oven. The gunge shouuld then be freed up!
Using a bit of methanol or nitro fuel is a good way to clean up once the parts are free

Please see these excellent two videos for more advice and visit his channel, he is hilarious:
1)
2)

(Though I am only 17 please believe me, I just restored my old O.S 46 MAX AXto full working condition!)

Above post merged into thread containing the same videos and similar discussion.

Good job on getting your hands dirty

Would like to add links to  Youtube videos on 4 stroke engine maitenance. ASP 4 strokes are similar to the OS shown.
This is not my work. the credits go entirely to the person who made them. I am just posting the links as the stuff is jolly important and hard to come by.



Anwar, I am not tech savvy- if the links don't work, search 'OS 4 Stroke disassembly/assembly" and post the correct links please
thanks & regards
Avijit

I better leave it to Anwar. there are actually 3 videos- one on disassembly and 2 parts on putting it back together. there is a 4th one on cam timing as well. I seem to have posted the same link 3 times.
Anwar, could you please sort out this mess I have made of an important sticky topic and post the correct links
regards
Avijit

Avijith bhai - You seem to have posted the same thing 3 times.  I removed the two duplicate posts. 

When you embed Youtube videos, just paste the link  as regular text, no need to use the "Embed video" option. If any minor adjustments are needed I will be glad to assist.

Could you please post the links to the other 2 videos. Search youtube to "OS 4 STROKE ASSEMBLY" they are by the same chap.
that is what i was trying to do when the same video came 3 times.
Thanks for tidying up
regards
Avijit

thanks for posting the videos Anwar. There is another video by the same chap on adjusting the CAM position. If the cam is not properly set, the valves won't open and shut at the appropriate time and the engine won't run. I am waiting to try taking a 4 stroke engine apart. so if anyone has a non-working one, i would be glad to try fixing it. Only thing is I can't guarantee good results.
Avijit