Hey, i'm orgianlly from Australia and my dad had an 83 RX-7 back home that had 135 hp or something along those lines, my dad the reason for the differeacne is the exhaust set up and the size of the jet's used in the carb. Now i've a pretty damm good free flowing exhaust but want to know if anyone has ever changed the jets in their carbs. I know you need a second feul filter, a stronger fuel pump and such, but want to know if A) it would really make any difference and B) what sizes to use to get the most out of the carb. Any help would be great, thanx.

Pistons

 

read this it may help

carb stuff

 

can't change jets on the stock carb

 

LOL. How much do you wanna bet?

 

Yeah LOL Easy to change, once carb is apart

 

I would bother changing the jets unless you perform some other modifications. The best thing you could do now is get a decent fuel pump as the stock pump can have trouble keeping up with even a slightly modified engine.

 

what i meant was, can't change the jets w/o taking the whole freaking thing apart, which if you don't know what you're doing can be a royal PITA. well, taking it apart isn't too hard... getting it back together and working is another story

 

Rob at pineapple racing told me that "185 secondary jets are a good place to start." So start with 185 and go up a size if you are too rich, and down a size if you are running too lean. Fiddle with it until your seat of the pants dyno says you have it right. Paul yaw has a really good write up on tuning carburators. http://personal.riverusers.com/~yawpower/

 

are you talking about the air bleeds or the fuel jets?

Neanderthol if you want to go rich with the FUEL jets you need to step up...if you want to go leaner then step down a size.

With the air bleeds is the opposite. Go bigger to go lean (but mostly at high RPM) and smaller to get richer.

Hope this helps...because you had me all confused. I just tuned my carb today and got the mid/rpm set...I will play with the air bleed tomorrow to richen the high rpm band a bit.

1Bad85Rex who says you have to take the whole thing apart. It's only like 6 or 7 screws...and the big air filter bolt in the middle. You crack open the top of the carb and play with it. Just make sure you don't damage the gasket and that you don't drop the float pins inside your engine. You can reuse the same gasket a couple of times if it's new. While at it check the float levels and ajust as described in all the sites here mentioned.

What is funny about all the sites (nikki ones) that I have seen is that NONE show the location or a picture of the air bleeds, fuel jets etc. It's like they are saving this information like if it's a government secret. Well it's not! but it would help a lot if they show a picture...everybody is talking about change this jet and this whatnot and I think it just gets people all confused. A carb is carb...the nikki is no different. I have gotten much more information by reading some sites with information regarding tuning webers, holleys...etc. Then again I'm no expert, but I ain't afraid of learning.

 

Oops did I say it backwards? sorry man. I had it right in my head but it came out backwards when I typed it. Where do you find alternate air bleeds anyway? I know mazdatrix sells jets.

 

Neanderthol I was going to ask the same question about the air bleeds.

Since I got 3 carbs I am thinking about soldering them shut and redrilling. But I know this is just the last hope...