4A084
cog reduction
42mm mukini and new plenum design
new 4 in 1 header

Has anyone tried this setup and or part of it (Carb, Plenum) on a 4a084?

Thanks,
Jim


https://www.youtube.com/watch?v=7ytQV37IV3Y

https://www.youtube.com/watch?v=RslIuJx2uk4

That engine belongs/belonged to Eskimoboy here. He's moved on to an Ecotec setup now but his last setup on that motor was the intake that I build and the Empi carb. I talked to him on the phone a lot and sent parts to him because it's so hard to get things shipped where he's at.

That engine belongs/belonged to Eskimoboy here. He's moved on to an Ecotec setup now but his last setup on that motor was the intake that I build and the Empi carb. I talked to him on the phone a lot and sent parts to him because it's so hard to get things shipped where he's at.


1. What is a Empi carb?
2. Is it better than the stock carb/some more HP on a 4a084-4
3. As for the intake, same question, is it better and more HP w/that carb?
4. If so what is the difference and where can one obtain such when ready?

Thanks,
Jim

P.S. Is it possible to set up a twin carb system, one carb for one side/bank and the other for the other bank of cylinders? Or is it better to have a better intake and single double barrel carb?

Question, what is the max CFM that these 4a084 can handle with the right intake/exhaust in reference to just needing more HP sometimes if the boat get a little bogged down.

Pretty much all your questions have been covered here. I would suggest you look over the 4A084 forums here. There is also a complete engine book there that can be read or downloaded. You could also start your build thread and ask questions if you have trouble finding these things and others can help you find them or answer a specific question. It will also help you keep all your info organized.

Pretty much all your questions have been covered here. I would suggest you look over the 4A084 forums here. There is also a complete engine book there that can be read or downloaded. You could also start your build thread and ask questions if you have trouble finding these things and others can help you find them or answer a specific question. It will also help you keep all your info organized.
Ian new to the air boat world just. Got a 116 mini pro with the 084 on it . With a mutin carb anyone know wat jets should be in it

I/m not sure what boat you have, Chuck built one with that setup. He most likely pot the best ones in it for his area. what is it doing?

How you doing Papee been reading a lot of your post before I even got my mini I live on a river here in Mississippi ever summer it gets to low to run my Jon boat me an my buddy's have been looking at a better way to run skinny water some of them went with jet drive they haveing problems picking up rocks lol I studied on the mini all summer an decided to give it a try think it is awesome going places on this little river never been in my job boat now back to the question the man I got it from was the second owner name was Steve he put this carb on an took it to Chuck but wasn't feeling well enough to help him set it up I was have to pump it every now then to keep my rpm up move the needle down one notch runing petty good own top end rite still has trouble coming off bottom end

An Papee will a champion spark plug work in a his 084 I hadn't tried to take one out yet hadnt gather enough info on it yet to see if I can get what I need at an auto parts store or if I need to order what I need

Do you have a temp gauge? Sounds like the primary jet needs to go bigger but before you do anything try running it without the air cleaner. If it straightens out you have to go smaller.

I think there here is a thread here somewhere about what plugs and wires work. I've never changed over because Saturn is close to me and the plugs last a good while. I had one set in for six years.

Thanks Papee I try it tomorrow but the guy that put it on had to put tape on it to get it to run I've tryied adding an take into off if I take to much off it don't want to run make me think the jet mite be to big before I start moving or changing out I was wanting some input I got a jet tuning kit the gut give me when I bought the boat

Hi scooter and welcome to the site...I'm having a hard time following what you're trying to say to many typos...

The way I'm reading it is that he has a dead spot at lower rpms and doesn't know if he should go with larger or smaller jetting.

if I am understanding correctly, you dropped your needle down 1 notch,doing this will lean it out. just a little.
where you are stating that you have a bog on the bottom end, there are a few things to think about.
is the choke seated. is the pilot jet plugged?
on a mukini carb, from closed throttle to 1/4 throttle, the factors involved is the pilot jet, and the cut on the throttle body,
it isn't until you get past a 1/4 throttle, where the needle jet, the jet needle, and the main jet come into play.
also the choke might be leaking a little. which can give a bog on the low end also.
with out knowing what the previous owner did to tune the carb to the motor, it can be a good guessing game, without the proper gauges and equipment.
these carbs are simple. but you need to tune each part of the carb separately. make one adjustment, at a time, and EGT gauge would be very helpful to know if you are running to rich or to lean at each part of the throttle,
if you do not have a EGT gauge, the only method is to look at the spark plugs to see what color they are running at.

and if you do not understand how each part of the mukini carb works, it can be very frustrating, to say the least.
but before just looking at the main jets an changing them out. (which will not do anything for the idle circuit of the carb)
you need to know if the idle is running to rich and flooding the motor, or running lean.
anyway, have fun and let us know what you find out.

Thanks for typing all that out Bart. The reasons you stated are why I asked him to run without the filter and report back. if it's close it will either run better or worse and that will give an idea which direction to go next,

a couple of questions i have, about installing a EGT sensor on the exhaust of the 4A084 motor
how far would a person want to install the sensor from the engine. and what would be the target temp. that is recommended at idle, 1/4 throttle, 1/2 throttle & full throttle

all my experience is from dealing with 2-stroke motors.
and just changing the location of the sensor from 1, 2 or 3 inches from the exhaust port. your temp can vary a couple of hundred degrees.
i would need to pull up the paper work, but if my memory is some what close
at 1/4 throttle the temp should be around 400-600 degrees
at 1/2 throttle 800-900 degrees
at 3/4 to full throttle 1150- 1250 degrees
and if it goes over 1350 for more than a minute, i probably will be rebuilding the top end of the motor

back to talking about the 4a084
there has been discussion about installing a sensor on the head , and the temp should be around 450 degrees. once the motor has warmed up, will the temp stay consistent, at 450 degrees from idle to full throttle?
or does it vary as to the throttle position, like the 2-stroke motors?

i know that Papee has gotten real good knowing what his motor is doing. just by reading the oil temperature.
but has anyone installed an EGT sensor on the exhaust pipe of the 4A084?
in reading some of the forums where the 4A084 has been installed on some small planes. and they put on a Mukini carb, they only mention what main jet they have used,
but to tune the Mukini carb to the 4A084 motor, you would need to have the correct sized pilot jet, needle jet, and jet needle, and main jet. so you are running with the correct fuel mixture throughout the throttle range.
and the simplest way i know how to do this, is by reading the exhaust temp.

and has been stated on the 4A084 motor due to the stock intake configuration, cylinders 1 & 2, will run richer than 3 & 4,

there are just a lot of variables to look at, and take account of.

i have enjoyed reading about the trial and errors, some of you have dealt with in just changing over to the solex carburetor,
there is a good learning curve, on any changes that are made.
i am curious to see what Scooter has for all the carb specs on this set up, that he has.

Just to be clear I watch my oil temp. Aerokirk is the only one I know of that has any seat time in running egt gauges. as far as location you can skim through Corkys build and see where he pot his.

Papee, after looking at Corky's build, he is using the O2 sensors to monitor his fuel mixture, which as you think about it, all the modern engines all have an O2 sensor installed on them so that the EFI can control the air fuel ratio. that is one nice thing about Aerokirk and Corky's builds, both of them have taken time to talk about some of the gauges that they are putting on and the reason why. there is not a lot of information about the EGT sensors on a 4 stroke motor, except for the diesel.
but it is pretty straight forward if you install an O2 sensor, and that would give an person some good information on what needs to be adjusted when tuning the carb to the motors. I know when Corky stated that a descent set up starts at around 200.00, I get the thought, man I don't want to spend that much, but all I have to do is look at the time that I will spend making adjustments to the carburetor, which can be very frustrating, to say the least.
on a 2 stroke motor, having a EGT gauge takes so much of the guess work out of it.
at the moment I am still playing around with my 4A084 motor, and am looking at trying an Mukini carb on it. mainly because I have quite a few of them sitting in my shed, and I understand a little bit about how to tune them, but now I see the time savings of having the proper diagnostic's attached the motor.
at least that is what I am looking at now.
below is part of Corky's thread on what he shared.
thanks again for all the information that everyone has taken the time to share on this forum.



Hi Ted...Companies have come a long way the past few years with the air/fuel monitoring equipment...At one time you needed a laptop or bulky hand held unit to monitor values using a broadband O2 sensor...Now quite a few places offer a more affordable set-up that's just an easy to read digital gauge and the O2 sensor...I've got a hand held unit that has input for the tach as well as the O2 readings viewed in realtime or the capability to record a graph for a vehicle running a timed session like the quarter mile... When the run is over it will show the timeframe,RPMs, and any spikes/leanouts as the vehicle runs down the track...Obviously we don't need any of that for this application...

The simple O2 gauge/sensor will give all the info you'd need to monitor your air/fuel ratio...Unfortunately even the simple set-ups are around $200.00 no matter which company you buy from{The better quality O2 sensors are'nt cheap even on their own}...Not the cheapest gauge on your boat that's for sure but it takes the guesswork out of tuning the carb....Here's the company that I purchased my equipment from http://www.innovatemotorsports.com/ This is the most popular company and the accuracy of their products are second to none....There's lots of videos and info available on that site pertaining to tuning just about any engine...


http://miniairboatassoc.com/forum/images/misc/quote_icon.png Originally Posted by aerokirk http://miniairboatassoc.com/forum/images/buttons/viewpost-right.png (http://miniairboatassoc.com/forum/showthread.php?p=33038#post33038)
Corky... I noticed in one of your previous posts that you intend to add an O2 sensor to assess mixture settings. I'm interested in monitoring my exhaust to see if I've got the proper jetting in my Solex carb. What equipment do I need to monitor that and how expensive is it?

I'm going to run a cylinder head temp gauge...I would assume that gauge would have a steady reading compared to an exhaust gas temp gauge...From the brief conversations I've had about the running temps, it seems the 084 does have the ability to get hotter than that 475*CHT that is the target range at least with running the circle S redrive.. In my case I put the thermocoupler at the rear cylinder on the oil filter side...Reason being you'd want one of the rear,somewhat shielded{as in running hotter} cylinders... And while the aircleaner housing does block some air on the other side it would be cooler from the incoming air charge whereas the oil filter is dissipating heat adding to the overall temps on that side.. Overthinking it ?? Mabe...
In our application of the 084 without it's cooling system and shields in place plus a different exhaust I was'nt sure on just where "normal" would be for an EGT gauge or even the wideband O2 gauge for that matter...That's why I want to run the engine in it's "stock" configuration with the original carb and see where the readings are for a baseline..
I would'nt know if I'd even trust a target EGT reading in the military manuals if one was found other than to see how far off we are from what they've had to begin with..
The bottom line is to run the 084 in as close to factory configuration to get what is a "normal" base reading in our application then do your mods and see if any improvements/set-backs are happening...

Sorry guy been real busy last couple of days .iam new to all this an I appreciate all the help coming from this site .But I went back thru th e carb made sure it had stock jets in it. Runs good at idol runs better on top end but still wants to bog coming up off bottom end I tried to run it without the air cleaner it will not run I even have to tape half the air cleaner off to get it to run.after reading Corky replays i am Prety sure I don't have enough heat .wast sure what it was suppose to be I had put a smaller jet in an the heat was coming up over 200 an I stopped it an went back to the stock one.an I have noticed that wile during the day when I go to hunt it will run pretty good .but went dark fall an the temp is lower on my way back it cuts up some. LOL but reading the replies trial/ error I get it rite .
Question for Corky reading some of Papee s forum on RPMs iam have ing to get up over 4000 rpms to jump up on plane an stay around 3000 to stay on plane in deep water . Not sure wat the prop is I was told it was a whirl wind not sure gonna try to get some pictures of it see if y'all can tell . I really like to have one like Papee was talking about that would stay on plane below 2000 .wondering what prop yall thinks works best with the 084 my motor has a redrive on it
Thanks

4000 rpm is too high to get up on the water...3000 is better but still high for a direct drive..You want a direct drive prop to act as the governor keeping the max rpms at a safe level...From what you're describing I'd say you need a different prop if it's not adjustable...Post a pic of the prop so we can all see what you're working with...Also, get a tip-to-tip measurement for us too...

I mite of miss lead you mind has a reduction drive on it but I will have some pictures of it tomorrow if can figure out how to put em on here

Sorry about that I do remember you stating having a redrive in the other thread in any case 4000 RPM is still too high...The circle S redrive top RPM number to shoot for is right around 3000 RPM + or - depending on the prop........

Scooter posting pics is easy...Hit reply..Next screen in the bottom right hit "go advanced" which will take you to the full reply screen...click on "attachments" and load the image from your file...You may need to resize your pics before trying to post them on the site depending on how big they are..