internal cab parts question

Why is it that you have to keep all the parts separated from the other carbs? all the carb parts look exactly the same, same threads. (as far as the bottom end of the carbs). will the jets interchange? they all have the same number on them.

 

They have lived this long together in thier own little carburator communes. each needle and seat fit together like a puzzle, as do the rest of the bits. Dont break up a family if you dont have to.

unless you are replacing a partt, it will nearly always be happier back where it came from - especially after 20+ years.

And in recent threads, I just read that the #2 and #3 jets are slightly different than #1 and #4 - to help the middle two cylinders run a little bit cooler since they have much less cooling area.

my two cents

 

This is not true for all the models. Flipping through the Yamaha parts site the only '82 with different jet sizes it the 650 SECA turbo.

 

I missed the bit about the 650 turbo. I thought it was more-less across the board.

 

The 2 inner main jets are one size bigger than the outter........you know why????

 

to let more fuel in to keep the two middle cylinders from overheating. Since the turbo motor has more pressure for more power, it is running hotter to begin with.

 

U win the prize

 

Seems some other models had different middle jets too. Yamaha does not apear to have a hard and fast rule with this mod.

 

Middle jets reguardless of TURBO or not on inlines need to be richer because the middle of the engine gets hotter, there not exposed the the air as much and the richer mixture cools the center cylinders a little more.

 

The 650 turbo has 127.5 or .050 thousands holes and the outter 132.5 or .052 thousands holes on the inners( one jet size larger) on the Makuni Carbs.