hi all i have a 2001 scrammy 400 2x4 2 stroke, ive added a k&n and a hpd silencer, recently i blew a hole through my piston and it may have been caused by leaning out, it has a 230 main jet and i believe the needle clip setting is on the third one down from top. does anyone have an idea of good setting for me to run so that its jetted for the mods i have done. i ride at sea level up to 2500 above.
thank you for your help.
tom

 

Start here , lean out as needed .

Main 250
Needle clip one below center
Stock pilot - one turn out on the screw

 

then to start leaning it out properly would you recommend changing jets or needle settings?

 

ya if the idle is to rich then lean it out one half turn at a time, if the mid range is to rich lean it out one clip at a time, if hte top end is to rich then go down one jet size at a time.

 

after further review this evening the main is 240 the needle is the second clip from top and i didnt check the screw setting. i lost my piston while running in mid range, so im assuming that the clip should be lowered one or two down towards the tip. im also thinking everything else should be left alone. am i correct in assuming? it ran perfect till she blew the hole. it felt great from the bottom on through the mid and high seemed to stay in the sweetness.
thank you
tom

 

if it ran good on top and on the bottom but blew in the middle your correct in assuming to lower the needle, always start by lowering it to much. i would say lower it two notches and if its not to rich then lower it again and if when u get it to rich raise it until the burble goes away and then yoru good to go. do u need a bore or jsut new piston?

 

cylinder walls look perfect and rings were fine, so i think i will hone and install new piston, wrist pin and bearing. all though i need to figure out how to install new piston and get the rings pinched to go into cylinder.
thanks
tom

 

well alot of engine builders i have heard done recamend jsut honing and dropin in a new piston, either bore it or dont, cuz they say the clearences are really sloppy, i would say it its not bad take some fine grit sand paper and soapy water and use that on the inside the cylinder jstu to clean it up, then when your done wash it out with plain water and get it dry then spray some wd 40 in it and whipe it with a paper towle and if u see any gray in it from metal shavings wash and repeat till no metail savings come out, make sure u dont let it sit with wd 40 on it or water cuz it will rust almsot instantly. as for the rings have someone else hold the jug and u can guide it down the top of the piston then compress the rings and have then slowy lower it down but be sure u got the rings to seat into the ringland or else u will scratch your cylinder. good luck, scott

 

DONT YOU THINK ITS EASIER TO JUST PAY 15$ AND HAVE IT HONED SO THAT ITS DONE RIGHT AND YOU KNOW ITS CLEANED OUT? DO YOU HAVE ANY RECOMMENDATIONS FOR KIND OF PISTON? I HAVE HEARD TO REPLACE WITH STOCK , BUT OTHERS SAY REPLACE WITH WISECO.
THANKS
TOM

 

no cuz if u really wanna do it right bore it then hone it. i read teh whole article backwards and forewards in atvsport a couple years ago about this. just honing it will leave your clearences to sloppy. get it bored then honed and put in a wiseco.