0.064 over what jet do I need?

[littleape]

Hi guys, I have a 1990 150hp crossflow that has a 0.064 bore, I believe I need a larger jet for it but not sure what exactly (part number)


Thanks

 

[Faztbullet]

Is it a single cylinder that's over or all of them??? You need to jump at least two sizes, I myself would jet it a tad on rich side with that Siezco piston....60C part # 321449 or a 58C part#321731. MAKE SURE the cooling system is up to par with new impeller and t-stats and you take engine thru at least 4-5 heat/cool cycles to temper the piston.

 

[littleape]

Is it a single cylinder that's over or all of them??? You need to jump at least two sizes, I myself would jet it a tad on rich side with that Siezco piston....60C part # 321449 or a 58C part#321731. MAKE SURE the cooling system is up to par with new impeller and t-stats and you take engine thru at least 4-5 heat/cool cycles to temper the piston.

OK will do thank you.

 

[jimmbo]

I wouldn’t rejet it. The carb will supply the proper mix to any and all air flowing thru it. A slightly bigger carb is what is really needed, but there isn’t one. If it has 0.065 overbore, it’s gonna bust a liner soon enough. I guess too rich will cool the piston a bit.

 

[littleape]

So these carbs are shared between two cylinders. If only one is oversized do I need to replace both or one of the jets?

 

[Faztbullet]

Just the bored one.....Rule of thumb is .020 and below stock jet is fine, .030-.040 need to up one size,.044 and up two sizes

 

[littleape]

Just the bored one.....Rule of thumb is .020 and below stock jet is fine, .030-.040 need to up one size,.044 and up two sizes

Perfect, thank you.