blown motor help

[trx]

i have my orignal motor for my 250r sitting around but the head is blown , cylinder wall is cracked and when i took my pipe of i found my rings for my piston and sand lots of sand and right before it blew i was doing donunts in 2nd gear and heard a loud pop from the silencer then took of and it died and kick starter was locked i want to rebuild it but i wonder if something is wrong with trans becouse its missing 3 teeth from the front sprocket but draid oil but no shavings and there was sand in the airbox with k&n filter no outerwear what needs to be done to it to have it running again. thanks

[ky 2stroker]

so it sounds like you sucked a bunch of sand in the motor and it was just to much for it and it took a dump. when you say your cylinder wall is cracked do you mean on the outside or inside the bore. and it doesnt sound like you have any trans problems if you didnt find any metal shavings or chunks in your oil. broken sprocket teeth is mostly from just normal riding wear and tear. is all the rest of the teeth real sharp and pointed? that means they are wore out.
just go through and inspect your crank and bearings good also. it might be good to go ahead and split it and clean it out for good measure

[Ed Gein]

I agree........split it and check the cases for any more sand or misc. debris.....since you have it split, it's a good time to replace any seals or bearings that need it before doing the top-end..........and sprockets are dirt cheap........

[trx]

its more like deep scracthes on the skirt

[ky 2stroker]

oh well scratches arnt really that big of a problem, you just need a bore job. just check with your local bike mechanic or whatever and they can help ya out and tell you how much you would need to bore it to clean up the scratches and tell you what size piston you would need.

how about the combustion dome in the head? is all pitted out and stuff?

[trx]

its all burnt up the whole dome is black

[Ed Gein]

Yes, but is it pitted, scratched, scraped, or just black?

[ky 2stroker]

if its just black then its carbon. I have this little sand blasting cabinet and I just use that and sand blast my whole head and clean it up when ever I do a topend. its probably the easiest way to get rid of carbon build up quickly that I know of, you just have to wash it really really good after you sand blast it.

[trx]

its pitted and scracthed

[Benny]

well ull prolly need a new head and id split the cases and clean everything really good and figure out why sand got in the engine and get your cylinder bored