Chuysrt Posted September 21, 2020 Report Share Posted September 21, 2020 Whats up guys i got a 2002 banshee all stock and it that time for some mods i mostly do trails and maybe a race here in their im not trying to go all out but i am considering maybe a 392 or a 4 mill and anyone help with some advice on which route to go iv seen alot of 392 take out 4 mills what you guys recommend thanks in advance Sent from my SM-N975U using Tapatalk Quote Link to comment Share on other sites More sharing options...
grantevans713 Posted September 21, 2020 Report Share Posted September 21, 2020 A 392 is a stock stroke with 68mm bore, to get the most out of it you would want to go for a 4mil and make it a 421. Going that far with the bike can be more expensive, so my recommendation would be to start with the basics. Get an adjustable timing plate, some aftermarket pipes, chariot reeds, and some 34mm carbs. These mods alone will add a ton of power and throttle response to your bike. You will need all of these things if you decide to go to a 392 or 421, so might as well start there. You can also get a lot more power out of your bike by getting port work on your cylinders. If you have these things and later on want even more, go for the full 421 setup. I say to do crank/cylinders at the same time because it's not that much more of a stretch to pull the crank once motor is out and cylinders are off. If you start with just the 68mm bore and later decide to do the 4mil as well, then you will need to change from 513 pistons to 795, get cut domes instead of standard, and also need to either change your head or get a spacer plate. 1 Quote Link to comment Share on other sites More sharing options...
Chuysrt Posted September 21, 2020 Author Report Share Posted September 21, 2020 A 392 is a stock stroke with 68mm bore, to get the most out of it you would want to go for a 4mil and make it a 421. Going that far with the bike can be more expensive, so my recommendation would be to start with the basics. Get an adjustable timing plate, some aftermarket pipes, chariot reeds, and some 34mm carbs. These mods alone will add a ton of power and throttle response to your bike. You will need all of these things if you decide to go to a 392 or 421, so might as well start there. You can also get a lot more power out of your bike by getting port work on your cylinders. If you have these things and later on want even more, go for the full 421 setup. I say to do crank/cylinders at the same time because it's not that much more of a stretch to pull the crank once motor is out and cylinders are off. If you start with just the 68mm bore and later decide to do the 4mil as well, then you will need to change from 513 pistons to 795, get cut domes instead of standard, and also need to either change your head or get a spacer plate. Appreciate the info so yesterday we took the head off and noticed aftermarket pistons and porting but to be honest we don't know what might have been done to it and as far as pipes i bought some used t5 toomeys for 150 Sent from my SM-N975U using Tapatalk Quote Link to comment Share on other sites More sharing options...
grantevans713 Posted September 21, 2020 Report Share Posted September 21, 2020 That's a good deal on toomeys. If it already has porting, what was your piston type and size? Top of your piston should have some numbers, 4mils run 795s. A standard bore 4mil would say 795M06400 if a wiseco, you can tell your stroke and bore size by reading those numbers. If you already have some port work done, and you've picked up toomeys, just get your reeds, carbs, and timing plate. With these things you will be extremely happy with the performance of your bike without breaking the bank. When you start going into 4mil it's usually because you blew up your motor and it was getting rebuilt anyway. If you want some QOL upgrades, I'd recommend pulling your transmission and sending it out for a ProMod upgrade. There is a lot you can do to your transmission that will make riding the bike much better. I'd get this done before you start replacing other internal parts. Quote Link to comment Share on other sites More sharing options...
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