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Discussion Starter · #1 ·
I ve read several times that bikes must have different jet sizes in the same bike..


Like 130 for cilinders 1 and 4 and

135 for 2 and 3,...


What is the reason for that?

most bikes ive seen here has like one single size for jets in all cilinders.. but i think that is not correct (because of what i read)..
but i cant explain why is not correct.. .. and why bikes should have diferent sizes on cilinders 2 &3 than 1 and 4

can someone explain me why is that?

thaanks!
 

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I'd surmise that the two center cylinders in an inline 4 are going to be hotter than the outer 2 cylinders, i'm not sure how jet sizing works, but if 135 lets in more fuel and 130, the center 2 cylinders could run rich and a little cooler.

Just a guess.
 

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The Cruising Gunsmith
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I'd surmise that the two center cylinders in an inline 4 are going to be hotter than the outer 2 cylinders, i'm not sure how jet sizing works, but if 135 lets in more fuel and 130, the center 2 cylinders could run rich and a little cooler.

Just a guess.
True, but it also may be due to the fact the exhaust paths may not be symmetric across the cylinder bank due to physical length and they have to dial the center pots in different?

I'm surprised they would go up a full +5 just for cooling, that's a lot of change. When I changed the mains +5 on my 750 twin, it made a big change in running.
 

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Discussion Starter · #8 ·
it is indeed to help cool/prevent det in th einner 2 bores, my zxr400 had 88 jets in 1 and 4 and 90 jets in 2 and 3, this was after being setup on the dyno.

WOW i was llooking for this answer loong time ago!.


al this came actually cause i couldnt carburate my zx400..
but fynally i did i put 95 and 100 might be cause i live in altitudes..

have some pics of ur zx400?

nice bike.. but hard to find supplies
=P
 

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WOW i was llooking for this answer loong time ago!.


al this came actually cause i couldnt carburate my zx400..
but fynally i did i put 95 and 100 might be cause i live in altitudes..

have some pics of ur zx400?

nice bike.. but hard to find supplies
=P

my bike now ahs 105 main jets in all 4, to go with its micron race system and k&n airfilter, airbox snorkel has also been removed.

ill get some pics this weekend
 

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Discussion Starter · #10 ·
Ine has 100-95-95-100...

it was the best combination.. but still for me needs more power... its just so hard to carburate this bike properly at altitude! =P
 
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