'78 1400 question about .015 over bore

[monk-monk]

Im going to rebuild this powerhead and im thinking about going with a new set of .015 oversize pistons...if i do that, will i have to increase the jet size in the carbs and will the stock reed settings be ok...i realize that amount of overbore isn't too substantial...but i have the opportunity to ask, so i figured i would..Thanks!

 

[Faztbullet]

Re: '78 1400 question about .015 over bore

will i have to increase the jet size in the carbs

You can safely go up to .020 oversize on stock jetting....

will the stock reed settings be ok.

Yes.. Just remember the reeds are just a valve that opens and closes due to crankcase vacuum and atmospheric pressure.The stock reed system flow more than enough to supply engine..

im thinking about going with a new set of .015 oversize

I suggest you use a Promarine,Sierra or Mallory piston for the rebuild as I personally do not like the Wiseco(siezeco) pistons. They expand to fast in a inline engine and the additional clearance needed to keep them from cold siezing makes a noisy engine untill its warms up...(piston skirt slap)

 

[monk-monk]

Re: '78 1400 question about .015 over bore

10-4 Fatzbullet...thanks for the help...which one of those 3 do you recommend...?