slimguy379 Posted March 14, 2014 Report Share Posted March 14, 2014 So I pulled my motor stripped it right down. While I have it broken down I'm just curious what advise there is to make this a 2 stroke devil. I am running t5s, i am going to adjust for +4 timing. I want to buy new cool head with domes, modded star shifter, I would like a decent bore kit for a decent price but I'm lost as to what to buy seems you boys don't care for Athenas kits. I'm new to 2 strokes, but I do know engines. You guys talk about 421 cubs, now I take it those are stroked motors and use a "stroke" crank as in it has a longer stroke than stock. I'm running stock carbs and I'm curious as to when the cut off is till when you need bigger carbs. Ik I could build a bad ass motor for $3000. But I'm not looking to spend that much just trying to get an idea of what I should do and get some direction. Quote Link to comment Share on other sites More sharing options...
NYUK Posted March 14, 2014 Report Share Posted March 14, 2014 4mm stock cyl, ported, is a stout motor built right. for 3 k you can make some decent power. Quote Link to comment Share on other sites More sharing options...
slimguy379 Posted March 14, 2014 Author Report Share Posted March 14, 2014 So stock cyl are 64- 64.5 mm? So a " big bore kit" 392 is only 4mm over stock. Where do guys get 421? Quote Link to comment Share on other sites More sharing options...
NYUK Posted March 14, 2014 Report Share Posted March 14, 2014 contact redline, hq sponsor, 421 serval, making decent hp. Quote Link to comment Share on other sites More sharing options...
slimguy379 Posted March 14, 2014 Author Report Share Posted March 14, 2014 I bought the motor in parts, never paid attention but my crank says hot rod, what's the best way to tell if its a +4 mill crank? Quote Link to comment Share on other sites More sharing options...
NYUK Posted March 14, 2014 Report Share Posted March 14, 2014 if you don't know what your looking at you can`t tell. put up a pick of the rod pin, outside crank wheel. Quote Link to comment Share on other sites More sharing options...
Surfrjag Posted March 14, 2014 Report Share Posted March 14, 2014 Does it have a stock head and a .020" base gasket? If so its probobly stock stroke Quote Link to comment Share on other sites More sharing options...
Buckwheat Posted March 14, 2014 Report Share Posted March 14, 2014 I agree with NYUK about Redline. I sent my cylinders to them and my bike literally rips now and it is a stock stroke. Quote Link to comment Share on other sites More sharing options...
Zillaguy Posted March 14, 2014 Report Share Posted March 14, 2014 A 421 is 4mm stroker (58mm stroke) and a 68mm bore... The best bang for your buck is to do a 4mm stroker ported stock cylinder setup... You'll need to have the cylinders ported for a 4mil, a 4mil crank 795 series Wiseco pistons, domes cut for the stroker, and some type of a cool head... Stock carbs are good to 80ish hp... You'll be fine on stock carbs... Bigger carbs are not all their cracked up to be on stock cylinders unless your drag racing all the time...... If you go bigger you lose throttle response, but they scream up top, and are slightly boggy off idle... Quote Link to comment Share on other sites More sharing options...
camatv Posted March 14, 2014 Report Share Posted March 14, 2014 my 40mm's are crisp as can be.. on a 350.. Quote Link to comment Share on other sites More sharing options...
slimguy379 Posted March 14, 2014 Author Report Share Posted March 14, 2014 So say I bought a 392 bore kit. Comes with head & cylinders. Now would I have to buy special stroke cylinders? Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted March 14, 2014 Report Share Posted March 14, 2014 I have 4 mil stock cylinder. I'm mid 70s for hp and a good amount of torque. My 35s are just as responsive as any stock carb. You can have your stock cylinders set up for a 4 mil, buy the correct domes, crank, and pistons. You'll be extremly happy with a good running 4mil stock cylinder. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 14, 2014 Report Share Posted March 14, 2014 my 40mm's are crisp as can be.. on a 350..^ fuckin really like this guys style..... Quote Link to comment Share on other sites More sharing options...
Zillaguy Posted March 15, 2014 Report Share Posted March 15, 2014 40mm carbs seem like way too much carb for a small motor... The smaller the carb the more velocity the intake charge has... Which will help primary compression a great deal.... With a big carb you decrease that velocity and get less effective crankcase filling... And you loose signal strength to mouth of the carb... Pressure is made by dead ends.. Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted March 15, 2014 Report Share Posted March 15, 2014 40mm carbs seem like way too much carb for a small motor... The smaller the carb the more velocity the intake charge has... Which will help primary compression a great deal.... With a big carb you decrease that velocity and get less effective crankcase filling... And you loose signal strength to mouth of the carb... Pressure is made by dead ends..Regurgitated Internet info. ^^I've ran 39s on a good set of stock cyls personally and they worked great. .....have you? Sent from a van down by the river Quote Link to comment Share on other sites More sharing options...
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