How well does your engine work after you rebuild it

well, if you want to clean the engine inside out! take it apart ( there is a certain way to do it) clean up the internals/ inspect for damaged parts, re-oil the internals with castor oil which is found in mother nature supermarket etc... put the engine back together carefully! re-seal parts needed to be sealed and your good to go! theres no need of re-breaking in the engine b/c it is already broken in , for me i run the engine rich a couple of runs then tune it up again! this is what i do! taking an engine apart isnt going to do anything bad! this is what you do to maintain your engine after a long long long usage! dont do this all the time , but as your question it doesnt harm the engine unless you mess it up!

i dont think emancipation007 means to clean his engine...
after rebuilding a engine it should work the same as what it did from new it also depends on how much you rebuild and for what reason you are rebuilding it...
replacing bearings and rods wont change the perfomance unless you replace them with ones that were not standard and also if you dont check them regularly and let them affect your tune...
you may have to run your motor in again if you do a full rebuild but if replacing bearings and rods i just like to run the car rich and just take it easy for 2 tanks or so...
you also need to look at wether its goin to be worth rebuilding cause depending on your motor it might be cheaper to just replace it..

rebuilding works most of the time, provided that there's no abnormalities found on your crankcase, crankshaft and button head. i personally rebuilt 2 engines almost from ground up, after broken in, it performs well. just that i maintain old exteriors

if u need to replace more than 3 parts one go, then compare the price of repairing VS buying new engine. most of the time its not worth it.

Replacing bearings and rod will only have a affect when there is play on it. Even if you think replacing a bearing is not needed then after replacing it the engine could sound and run smoother than before.

Roelof, i wanted to know if how exactly do we know if the crankshaft is bent? its hard for me to notice anything by simply rolling it at the edge of the table

The 13 - 14.5mm shaft does not bend, it does give some flex in the engine on high revs but it will not bend. The 5mm SG shaft can be tested to roll the crank on the edge (crankwall over the edge) of a flat surface with a right spacer under the tip of the 5mm shaft. When rolling the end tip must not wobble over the spacer.

so that means, there is probability it would bent for 1/10 engines. mostly its 12mm diameter.

1. some guy did asked me about, scratches/worn area on crankshaft. to be exactly on thrust bearing area. do we need to change it as a precaution measure?

2. tuned conrod, what does it do as compared to normal? im also lacking on this part

There is a difference in bending and flex. Scratches can be caused by flex but most engine suppliers will say it is dirt.

Tuned rod can mean anything and nothing but in most cases it will be lighter and having sharper edges.

yeah, sharper edges. light weight, maybe some mg's because of the cut off about the crankshaft bushing area. i was warn about the usage of this type conrod because o doesnt last that long.