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modded 426ex

3242 Views 22 Replies 5 Participants Last post by  SlammedRanger
hello first time posting on the site. i have a 03 400ex and going to bore it to a 426 i have a stage 2 hotcam big gun rev box white brothers e-series slip on exhaust im having gt thunder hd head studs installed and a 88mm wiseco 11:1 piston and have the head mating surface trued up and a port and polish atm with a 10:1 piston stock bore i have 168/42 jets in the carb with choke removed and an opend air box with a k&n airfilter with a precharger need a little help on starting position with the jets ive read alot of forums and think a 180 185 and 190 should be what i try any advice?
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thanks for the help and im allready 1 clip down on the slide pin and i bought a bored stock cylinder and a 11:1 wiseco 88 mm piston and the cooling i have air fins and an oversized oil tankand i am putting a spal fan on the rad with a thermo switch for automatic cooling no idea what else to do atm unless i put an extra rad on it and a 45 pilot will i really need to go that big?
ok ill guess ill buy a couple of jets and the cylinder i bought presleeved idk if it is a stock sleeve or not what would be the difference ive spent almost $500 so far tring to get everything to make my quad a 426 and i allready have a 450r timing chain that happened when it got a stage 2 hotcam
is there any good go to spots for jets and yeah i looked its a bored stock sleeve is that gonna be a problem?
ok well i just took the head and cylinder and studs to the machince shop its gonna be $275 for gt thunder studs installed true up the mating surface on the head and port and polish and and a valve job and clean up the head and i bought jets from 180-195 just to be sure and 45-48 just to be sure dose that sound like a good price for all of that machine work ( theyve been in buisness for 60 years and have amazing reviews even from a friend)
ok so another thing im going to bore open the exhaust header not to much just a little to help flow but i was using a DPR8Z ngk plug should i go to the DPR9Z ngk plug?
ok sounds good thanx slammed and others for your help ill update when i get my parts back from the shop
ok i got it all back together today and i did 185 and 45 jetsand 1 clip down from stock on slide it started excelent but it back fires with flames could an exhaust leak make it do this?
ok ill fix it tomorrow ... other than that running about 5 min around the yard at no more than 1/4 its amazingallready feel the power differance
its fixed put it all back to gether and she runs perfect thanks alot to all
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