jay85gs

Just installed a Mikuni setup on my 85 it was a hell of a difference over stock. Here's what you need if you don't have it.

You should pickup a Mikuni phh service book (ebay or wolfcreek racing).

At first my car ran crapy under hard acceleration(bog bog bog) but this is when you need to start jetting. I finally got to the pump nozzles and they were WAY TO BIG!!!!. They were a 90 and our stock 7's should have 40's. I didn't have 40's but I did have 60's and OMG!!!!! WHAT A DAMN DIFFERENCE! The car pulled extremely hard but still had a little bit of transition bog from pilot jets to main jets. My pilot is 62.5's but I think I'm going to go with 65's

Rx-7 doctor recomends 200 air jets 190 main jets and 40 on the pump nozzles.

My setup included a bunch of pilot and pump nozzle jets, the respeed fpg is fantastic.

I hope this helps a little..............................Jay

kuhlrx7

you tested them? you say our experiance, how many people are you? they were tested headup? same intake design used for each, not optimised intakes and lengths for each carb? same engine and exhuast tested for all carbs? can you post your test results and test rules for the club. I think many here would be intersted to see how and what you concluded. I have verry little experance with su carbs but find it odd that the su and dellorto were that close. I am talking from my own experance and what I can read thats published. Is kleinke a joint effort? a shop? a team? the carbs tested were thay all 40mm or 44s did all have the same air horn? is your all experances subjective or objective? not tring to be confrontational, but these are all questions that come to mind when I hear a statement like you or youall made that differs a little with what I have read or experienced. I will say most of what I have read shows webers with the flater power band. but this gets us off subject of the thread so lets help rx7learner out if he still needs it and please post your results in a new thread.

jay85gs

Nothing scientific just trying to help, it's all subjective, climate , atltitude, geography, setup, etc, etc...etc. What I ment our is (our stock port engine), but I guess that don't really apply either. Sometimes it just takes one suggestion that someone doesn't think of to help.

Oh btw my carb is a 44phh, good luck with you tunning........Jay

kuhlrx7

jay85gs I was responding to a earler post my post was some how delayed showing up.

rx7learner

The FPR I bought is not a return style its the 12-803 which is 4.5 to 9 adjustable. I got it dirt cheap (5$) and I have the Mikuni service book.

I figured my dilema with that model fpr may be the need to adjust below 4.5 since that is the lowest this FPR will adjust.

So in order to drop the pressure below 4.5, I ran the return line however I added my old FPR in between the return line and my carb outlet so that the fuel would not just free flow down the return line rather allow 1lb of pressure to be lost down the return line. If after fine tunning 4.5 is my best setting then I will dead head the T on the mikuni and run without a return line... however if I find my sweet spot below 4.5 I will purchase the 122-804 which will allow me to adjust from 1 to 4.

I was running at 4lb and OOOOHHHH MY GOD. The car was quick and pulled hard passed red line and best of all no fuel leaks. I'm a happy camper now and here's some pics of where I am at right now. Now comes the tweak stage. Thanks again.

n2318r

Also to clarify it depends on the engine. Whether it's a 13B peripheral port or a 12A stock port, the same carb wont make the most power on both. For example show me a del'orto that makes more power than a 51 IDA on a PP. Its different applications entireley.

Jim Mederer wrote a more recent article just a few yrs ago comparing 3 carbs. I can't lay hand on it now but think the mikuni made slightly less power than dell'orto, and a holley had highest peak hp. The curves are more important, for how you're going to be driving and other considerations.

Midwest 7's

iTrader: (4)

yea you should definitly get the 1-4 reg.
i like to run mine like 2.5 or so.

rx7learner

Looks like I'm dead heading at 4.5. I nearly sh?t... and so did my wife... went to get gas and filled up and she had to ask how much difference did it make. We are home now and shes in the bathroom. OK so i figured full tank of gas... and passenger... what could it possibly do.... pulling out of the gas station I broke loose & spun almost as if I wanted to go back into the gas station unintentionaly but it looked cool.

So my mikuni now rocks!

rx7learner

Midwest I didnt try that low... I will try in the a.m.

jonjonwells

Just a thought: I have the 4.5-9 version and it will actually adjust below that. Mine is fairly stable at 3.5psi.

kuhlrx7

great news. congrats. Im in the tampa area also and was when I had a 44 on a stock port 12a just looked my notes up from back then and my sweet spot for pressure was 4.2 psi yours looks to be above 4 also. It might be a sealevel thing, make sure you set up your fuel lines/fpr correctly asap to avoid any posible problems that could happen.

rx7learner

Cool! great to meet someone in the Tampa area with the same passion. I'm in the Cheval community up Dale Mabry by 54. I had a heck of a time finding a good speed shop around here. BTW Name is Danny if you ever need to do some work on a hot day without a cool place to do it... let me know my house is an ex model home and I have central air in my garage because it used to be the office. Thanks for the help.


Oh also... MIDWEST 7.... 2.5 did not feel as responsive... maybe you have a difference in jetting or porting than I do but it really did not feel as good but thanks for the suggestion.

kuhlrx7

I know about the speed shop issues most are either run as rice shops or v8 drag shops only around here it apears. there are a couple of good ones though but their hours suck.

rx7learner

I do not want to mislead anyone with this thread so I want to clarify the net outcome. The idea of using my old dial FPR in the return line to allow me to adjust the pressure below 4.5 using my Holley 12-803 FPR was a BAD IDEA. The pressure was unstable at higher RPMs and I felt it.

As jonjonwells mentioned above after dead heading the return line I was actually able to adjust the Holley down to 4 (lower if need be) even though the specs say 4.5 - 9 for part number 12-803.

Thanks jonjonwells.

djjjr42

I've got a Weber, but I'm pretty sure your timing should be advanced over stock timing with this setup as well.

crytical point

Im about an hour and a half away here in sanford fl and we have R.P.M racing and the owner "jonny" is absolutly awsome. He built my header, ported my intake, got rid of the rats nest, jetted and tuned my nikki carb but only charged me for the header and a new clutch. After he was done eliminating emissions on my 85 gsl and did some serious carb modifications I needed a new clutch because I have 4th gear chirp on a stock port engine at 7500. But we are working on a street port engine to get up to 9000 and use a holley to get a nice set up. This guy knows what he is doing and builds some nice cars and his work is up there with kilo and is pretty well known around here.