Carb Problems

[buzzbait]

Need some help with my 4A084 carberation. The original carb didn't perform well, changed to a Mikuni and rejeted. Works Ok in warmer weather, still needed to pump the peddle to get going. In the colder weather (35-40) it really hesitates and is a cause for concern. On the ice, I need instant response. Any suggestions on better intake?

Boat is a 2012 Airboat Pro
Motor:4A084
Prop: 3 blade 64" IVO
Turns 3200 RPM

Buzzbait

[Bandit64]

Good luck! I've got the same motor and have been trying to work out the carb issue as well. The mikuni didn't work? That's not good to hear cuz I just got one.
Have you had any issues with the bearings in the hub or with the clogged belt? My bearing got play and ate my belt. I had to pull my boat two miles out of the swamp.

[buzzbait]

The mikuni was working fine but the winters make things intresting. It's not as responsive in the cold so I wanted to try something different. Chuck has a guy finishing up a prototype manifold that will use a holly carb. I just now got off the phone with him and he said he will have pricing next week.

As for the bearing, I havn't noticed anything other than some grease in that area. Did the bearing give you any warning or just fail all at once?

[Bandit64]

The mikuni was working fine but the winters make things intresting. It's not as responsive in the cold so I wanted to try something different. Chuck has a guy finishing up a prototype manifold that will use a holly carb. I just now got off the phone with him and he said he will have pricing next week.
Did
As for the bearing, I havn't noticed anything other than some grease in that area. Did the bearing give you any warning or just fail all at once?

No warning at all. It rode up on the ring and shredded it until it broke. But I didn't feel or hear anything. Now I check for any slop in the prop.
Like I said, good luck with the intake. I'm one of the other guys waiting for one. Problem is the guy making them is too busy to get them done. I can't wait any more so I'm going to make my own.

[buzzbait]

I'm thinking the same thing but finding the right carb is proving to be a problem. The 350 Holly sells for about $300 and you have to pay about $100 for a core if you don't have one. The 1940 Holly is readly availible and should work just as well. I plan on checking the local junk yards, if you do find one I'm told it needs to be no newer than the early 70's.

As for the manifold, I'm going to wait a few mores days to see if Tony (the guy from Texas) can come through with a manifold. Eather way I'll need to bite the bullet and buy another carb.

[Bandit64]

I'm thinking the same thing but finding the right carb is proving to be a problem. The 350 Holly sells for about $300 and you have to pay about $100 for a core if you don't have one. The 1940 Holly is readly availible and should work just as well. I plan on checking the local junk yards, if you do find one I'm told it needs to be no newer than the early 70's.

As for the manifold, I'm going to wait a few mores days to see if Tony (the guy from Texas) can come through with a manifold. Eather way I'll need to bite the bullet and buy another carb.

Well what ever you end up with please post it with pics because this carb/ intake seems to be a major issue with the 084.
Im not a motor head so I have no clue but I'm really surprised that someone hasn't figured this out yet.
Thanks, Dan.
Oh one more thing, you are using the cogged belt drive from chuck right? Not the

[buzzbait]

Well what ever you end up with please post it with pics because this carb/ intake seems to be a major issue with the 084.
Im not a motor head so I have no clue but I'm really surprised that someone hasn't figured this out yet.
Thanks, Dan.
Oh one more thing, you are using the cogged belt drive from chuck right? Not the

Yup,
I'll get pictures as soon as I can get everything together.

[buzzbait]

Bandit,
Here are a few pictures of what I'm running now. If all else fails you can try this. I have no complaints other than rough running in our winter weather. All summer it ran great! The carb is a Mikuni VM 32-33, cost $80. I also purchased a rubber flange p/n M-VM340200K for $22, cable p/n VM28-VM32 for $17. Got all this on Amazon.com. I used a rubber adapter from the plumbing department to fit the air filter to the carb. Don't have a p/n for the air filter, I just went to the auto parts and picked something big. Adding lots of air made a big difference.

[eskimoboy]

Bandit,
Here are a few pictures of what I'm running now. If all else fails you can try this. I have no complaints other than rough running in our winter weather. All summer it ran great! The carb is a Mikuni VM 32-33, cost $80. I also purchased a rubber flange p/n M-VM340200K for $22, cable p/n VM28-VM32 for $17. Got all this on Amazon.com. I used a rubber adapter from the plumbing department to fit the air filter to the carb. Don't have a p/n for the air filter, I just went to the auto parts and picked something big. Adding lots of air made a big difference.

Hey Buzzbait hows that new reduction workin for you, any problems? Im currently using the vbelt reduction and have alot of problem with wear.Im waiting for my new reduction to arrive from Chuck. Im also waiting for one of the new intakes that Tony Stewart is working on.I havent had much problem with the original carb and I run winter spring summer and fall.When the temperature falls I put on a breather system that I made that runs from the exhaust to my carb so it doesnt frost up. I purchased one of Tonys intake setups because of the supposive HP increase, around 15 horses. Im waiting.

Nick

[eskimoboy]

Buzzbait do you have any videos online?

[Bandit64]

Hey buzz bait, thanks for the pics. I got a 42 mm mikuni at chucks suggestion. 158.00 used. This tony guy is supposed to be building an intake for this carb as well. BUT every time I call it's another week and I still have no idea how much it's going to cost.
I started on mi version tonight. I know there is a lot of physics to intakes that I'm clueless about but even if I end up scrapping it I had to get something going. I looked at a bunch of pics on line and their seems to be no real rime or reason to them other then getting the carb to talk to each cylinder. What the heck, I built my whole boat from pics and it turned out fine. ( except for this one very annoying problem).
This claim of 20 more hp with one of these set ups remains to be seen. My mechanic thinks its a lot of hp to get out of so little already by just a carb and intake. Tony, if your out there somewhere, I sure would like to prove him wrong!!

Eskimoboy, nice to see you chime in here. I really wanted to hear from some other 084 owners. I also have the clogged belt drive from chuck. And I did have a problem.
After about 8hours run time I noticed my prop had a little slop. Not wanting to take any chances I took it apart to change the bearings. (It's just a standard wheel hub and I know when my trailer tire gets slop it's time to change bearings. ) once apart I couldn't see anything wrong with the bearings.
I decided to replace them anyway. First problem, the new bearings didn't want to go on the shaft. I'm guessing because of the wobble ( about 1/4" at the tip of the prop) it kind of rolled the shaft like a mushroom. I had to beat the hub into the bearings ( didn't help the other end either) anyway I tightened everything up giving it just a hair more then I felt it needed. Ran it. Seemed fine. Took it duck hunting the next day and problem two (maybe my fault ) when we took of for home the belt snapped with no warning. I checked the prop and it had about 1/2" slop. The sun of a thing loosened up. ( yes the cotter pin was in place).
Chuck said it may not have been seated all the way and heat made it free up. That's the part I think was my fault. But I already felt like it was too tight. Probably the mushroom thing that fooled me.
I just put my new belt on and again it seems fine ( we' l see) this time I didn't take it apart. I just turned the nut tight cuz I think it's seated now( lol, not really). Tracks good and 0 slop. I'm going duck hunting Sunday so hopefully I won't have to pull the thing out again.

Two things though: 1. Buzzbait, I noticed your drive unit doesn't have a brace tying the top to the engine. Did you ever look at it from the side when someone is working the throttle? It's pretty scary how much the thing flexes. I added one to mine because of it. I'll post a pic later.

2. ...... When I remember 2. I'll post it. Sorry age is creeping up on me.

Thanks guys, Dan

[Bandit64]

Here is my brace. I tried just a flat bar but as you can see I had to add an angle.

[Bandit64]

My rig.

[buzzbait]

I have a short one I can try to get uploaded.

[eskimoboy]

Looking foward to seeing it, did you clock yourself to see what kind of speeds your getting in deep and shallow water. with my setup best I got in 3ft plus water was 33mph. I didnt clock myself in skinny water but if I was a bettin man id say 40mph.

Nick

[buzzbait]

Thanks for the heads up on the brace! I'll be adding that this spring.
Never checked my speed, not sure how to get an accurate read. Thats another project for summer.
I'm having difficulty in up loading my video clip. It may be my PC or CD because now it won't play. Seems to start and get stuck on one frame. The sound comes in and out, I'll keep trying.

[eskimoboy]

If you have an handheld GPS it will give you a pretty acurate ground speed.

[Bandit64]

Here is what I came up with. Does anyone see any problems with this?
Mind you it's not totally done.

[buzzbait]

Looks great! Maybe you should be selling manifolds. I found a larger airfilter worked significently better for me. I'm going to try something a little different, a carb on top of the manifold.

[eskimoboy]

Dan it looks great, what type of carb do you have there? Looks like your using the same intake tubes, do you think with that carb all 4 cylinders will get the same amount of fuel and you wont have an issue with half of the cylinders running either lean or rich? What made you decide to go with that carb? And the big question do you think you will have an increase in HP?
Thanks
Nick