ive done a bunch of searching and couldnt find ****, so what is the deal with these bad boys? i am some what interested in getting one i think. what are the requirements need to mount one...like what kind of manifold or what? also...what are the power gains from one. thanks

 

https://www.rx7club.com/showthread.php?t=387286


pm him, he's a genius, knows lots about mikunis, he can help you out.

edit: i see you have already contacted him....

 

yea...he hasnt replied yet though...so i thought id post this here thread.

 

mikuni 44phh with rb exhaust will net you 142hp. Mikuni is an extremley easy carb to work on and is very reliable. 80% of parts are still available. Need rb lower intake manifold. let me know if you have more questions. Oh by the way the hp increase is on a non-orted engine. rx7doctor

 

The basics of the Mikuni is the same as any other sidedraught carb. If you do decide to go sidedraught, you will need a new intake, and all the gaskets, a new or modified throttle cable and variuos other misc. parts.

But, since the mikunis are harder to find parts for, i would suggest that you go for a Weber. It will give the same amount of HP as the Mikuni and parts are easy to find. You could also go for the more tuneable Dellorto, basically the same carb as the Weber, but more tuneable. Parts are a bitch to find tough..

Ask Sterling, he is the carb guru of the forum in my opinion!

 

You can get any parts you need for mikunis from wolf creek racing in new york
www.wolfcreekracing.com

They are the east coast distributer for mikuni and can get you anything you need.
I switched to mikuni and was frustrated trying to learn to tune it until i got informed about wolfcreek so i could get the jets i needed.
I highly reccomend the mikunis, if you take the time to learn the carbs (get the mikuni factory manuals, their availible cheap on ebay) they are highly tunable and i have been able to get my car to run very well with these carbs, they even have a starter circuit you can tune so that cold starting is not a problem, also they flow well so that you can get good power as well.Mine is setup on a streetported 13b with racing beat exhaust, the exhaust is very important as they affect flow alot (probabley should be addressed prior to carburation).
also a good source of carb tuning is www.yawpower.com
its not really that hard if your willing to spend a little time learning the carbs a little bit, im not an engineer or anything and i figured it out.

 

I've searched previous posts using key word Mikuni but am still confused on whether or not the 44phh is enough carb for a street ported 13b. I think someone said that up to a certain rpm it worked well but had problems beyond that range. Is this true and if so, could it be due to incorrect jetting or would you just need a bigger carb? I think for a Weber DCOE, Rotaryshack said to use a 45 for a stock port and a 48 for a street port. Thanks in advance for any help on this!

 

Your reply indicates that you have more than one Mikuni on your ported 13B ??? You have dual sidedrafts ? Are they the 44PHH's ?

If so, did you have to a jet smaller to decrease since you have two ? Do you know what your RWHP is ? I can tell I need more than my one 44, but not alot more.
Interesting... ( strokes chin whiskers and stares off into space )

 

Back in the days, we used to run 44 mikuni without the venturies.

 

sorry for the typo. I only have one. However i believe since the chokes are adjustible you could run two and just put smaller chokes in them, the trick would be finding a manifold. i have never seen one for two sidrafts, just twin downdraft webers.

 

In the picture below I have a quick pic of my TWM DUAL Side-draft manifold.
The plans are to mount 2 Mikuni 44PHH on this manifold inducting my "street-port" 12A.

Since the venturi (chokes) are independant, I will be doing what rwatson5651 mentioned.. I'll have 41mm chokes feeding the fron and rear housing, and 39mm feeding the center housing ports. with a little different jetting on the outside.

the ports I am using is larger on the outer housings, and due to water column, should not affect my idle.


I also agree with alot of things being said here. I love the Mikuni.

If any of youhave any questions about them, please feel free to ask, I'll help where I can.

BTW, I concur about the recommendation to wolf-creek.

I have been dealing with Todd there for quite some time, he is a big vintage racer campaigning his 510. Not real good with rotary jetting, but as we all use these carbs we can maybe make a list of individuals set-up and optimal jetting

 

If so post a discription of how you did it, PLEASE post pics of the set up once mounted, very interesting. by the way thanks for the jetting info you pm'd me with.

 

this is actually a production manifold made of cast aluminum by TWM.. its part number oo48. If you click the pic for a larger version, i think you can actually see the cast part number.

Right now it is mounted to a front engine plate, bolted to a front cover, then the front engine mount... if you followed me thru that description... other wise check out the pic.

I set it up that way as a mock up to make sure it will fit in my chassis. I lowered the engine and trans like 5mm. and the engine isn't offset like in the SA/FB

The carbs will not fit in the car with the short stacks on, so I'll have to go with out-them, build a custom air-cleaner/plenum box, or go to an IDA...

from going through my mikuni jetting notes i have an idea of how to base tune to get them all going, My engine is a weird set-up, so it will take some fine tuning.


at this point i don't know what other info you would want to know, so feel free to ask away.

Did the jetting numbers i provided work well?

 

I don't know if this will help or not. but here ya go.

 

Rebello racing is the west coast dist for mikuni parts. They also build rx7 motors
and have knowledge about jetting and venturi size. 1-925-754-4871 fax# 1-925-754-4876. www.rebelloracing.com rx7doctor