what pistons to use

[jeffreynolds]

need some opinions on what type pistons to use in 1990 xr4 150 cast or forged

[Dave S]

I like using ones out of pre 1984 150s....They were stock, cheep, non wisco pin dropping - forged made by TRW. Did I say cheep.... :rolleyes: Ya get them out of old 150s with big rods and a good crank. ;)

[let's boot]

i have that same motor either i need a stator or it's just a slug compared to a 200 , any other easy mods 4 that engine? is it worth changing carbs and tuner or even switching to a horizontal intake set up?

[chris_lacey]

Isn't an XR4 a 2.4 150?
If that's the case, early 150 (2liter) pistons are not going to fit.

[M.CHAPMAN]

XR4 is a 2.4 liter with steel sleeves.

Standard bore is 3.375"
The old 2.0 150's are 3.125" on the bore

[jeffreynolds]

yes it is a 2.4 std bore i was wanting an opinion on the pro and cons for forged and cast and which would be best for slightly modified 2.4 max rpm 7k

[Dave S]

I was thinking it was a 2.0..150......Thats the bad thing about 2.4s who makes good forged pistons??? Wiscos are good but the pins fall out. Unless you send them out for top pinning. Arts will hold up pretty good and the SS ones are junk. The SS ones have what looks like two $$ on the under inside. Merc saved pennies and cost boaters $$ dollars with them . :(

[jeffreynolds]

well i knew i could get some very good advice from s&f ,what kind of money am i looking at for new top pinned wisecos

[Jay Smith]

Run the cast like came in it .... With forged you will have to put alot of piston to cylinder wall clearance due to expantion rate problems... Pro Marine is making a nice replacment piston that is lasting very well in our steel sleeve motors...Call Nick at Propelled Marine or Rick Racer I think both are dealers!