First boat! 2.4L 200hp Merc advice needed!

[wrightjd95]

Ah thanks. Also I'm seeing all these carb kits but none of them state if they're ethanol resistant. I'd like to do the ethanol resistant conversion. Does anybody know where to get one?

[SilverFox579]

I was pretty sure it had fuel stabilizers added.

At best, stabilizer would be good for a year under ideal conditions. I'd get rid of that stuff and replace with fresh.

[JOE54]

^^^^^^ +1 i know of no specific ethanol resistant kits i have cleaned hundreds of those carbs and from the first to the last oem kits were the same no change get the gasket kits and inlet valves separate

[wrightjd95]

Hello all,

I had to leave the country for a year due to work but I am back and work can resume on the boat.
I finally got the carbs off but it looks like the jetting is completely wild. I have attached images of the carbs markin. It looks like it has been restammed but I believe they are WH-3 carbs.
20240212_112718.jpg
The jets in the carb don't match up well with the table:
carb jet (Small).png
I removed the main jet from the cyc 1 and is a 078 which is the same as the recomendation, however the cyc 2 is 080. Now i wonder if the carbs have been ballenced in some way?

The ifle jet is way off from the recomended at 056 when the recomended is 046. What do you guys make of that? It is probably why it is running so rich.
Secondly the all carb 1 is missing the second vent jet and the other is 095 Everything seems way off.

I'm wondering if the previous mechanic just dumped in whatever, or it was done like this to get a lower compression engine running.

Also, are this specific jets, or can anybody point me to a generic supplier?

Many thanks

[EuropeanAM]

Those carbs are WH-39-1/2/3. Jetting may differ from what you're seeing for a WH-3-1/2/3.

[wrightjd95]

I can't seem to find any jetting chart for the WH-39 . I just want to make sure it hasn't been rejetted for high altitude then burn out the motor running it lean since I'm at sea level. The previous owner was at 6000ft, however, they may not have bothered to rejet,

[leonreno]

You could buy the service manual from Mercury, they would be in there. Worth the investment. But other maybe someone has the chart and can tell you.

[massbays]

Those compression #'s are not your running problem.
your options with a chrome bore are pretty limlted.
US chrome in wisconsin did the chrome for merc and way back, they had an exchange program.
Sounds like your on the right track with the re-jet.

[JOE54]

ill dig mine up in abit

[JOE54]

after speaking with TECH service no listing of size or location of jetting for WH39s , suggest you go to .084 in mains and .054 in idle jets , remove vent jets ; note this is a cross flow engine from the front the port venturi feeds the stbd cyl you may very well need the assistance of someone versed in jetting / two strk tuning for the correct fuel air mixture , be careful cyl damage can result real quick good luck ...JOE

[EuropeanAM]

I was able to find jet specs on the WH46 & WH49 (used on the 2.4-200 in that vintage)... how closely do they match what you had?

[leonreno]

You could buy the service manual from Mercury, they would be in there. Worth the investment. But other maybe someone has the chart and can tell you.

I maybe wrong on this because I was reading a thread on a different site where the guy is looking for the same info and has the service manual but it doesn’t list the specs for the wh-39, it stops at wh-29. So maybe that’s why it’s so hard to find the info for on the wh-39s, maybe Mercury never published them.

[EuropeanAM]

I do believe that to be the case... as I've referenced the manuals for either side of that serial number range 2.4-200hp.

[wrightjd95]

It's pretty close to those jetting values! Gives me a little more confidence. The number 2 carbs have a vent jet. From what I've gathered vent jets can be removed but it really affects fuel economy and I'm no racer here.

I'm in Mexico so finding a good 2 stroke tuner isn't going to happen. This is my vacation boat - I'm in Puerto Vallarta. There are yamaha/merc/honda dealer service centres etc which are staffed by university graduates, and plenty of big yatchs, super yatchs etc but nothing for older engines. It's the wild west when it comes to things like that. People here will claim they are experts when they know nothing.

I bought the outboard manual of course but it's missing the wh39 carb jetting table. I spent many a night poring over the manual in all its 600 pages.

I'll give the carbs a good clean then I'll post all the jetting values here and see what you all think. If you all approve I will do do a run up the trailer and take a video? What should I look out for if it's running lean? Should I be monitoring temperatures etc, looking for some advice here?

It's been a steep learning curve getting into this, boating in general, I didn't have a choice since as I said it's Mexico so I'm better off doing everything myself. Here is a photo of how she is looking now. I spent a good few hours sanding, cutting, polishing and waxing and it came out looking pretty good, there is a fair amount of scratches on the hull though which i will try to touch up:

20240213_143936.jpg

[EuropeanAM]

Perhaps good idea to perform a couple of plug reads at various RPM's. I have a hunch that these WH39's were something jetted specifically for your engine... perhaps from Day#1. But again- it's only a hunch. Given you the best info I can find after referencing before, during and after range manuals.

[wrightjd95]

Update:

Hello all! After fully rebuilding all the carbs and new fuel the engine seems to run a lot better. Won't start unless choked and throttle opened slightly. I feel like the starter motor might be worn and it is turning over slowly. I'm going to get a video of this so you all can tell me if thats the issue. It would also explain why my compression readings were low.

Took the boat out on the water. Absolutely flies! Holeshot is instant. By far the fastest boat on the water that day. I was flying past jets skis no problem was a joy, however, it seemed like the motor was overheating a bit since didn't like to idle after a fast run. I had a good tell tale but I have a question:

On the water pump tube - the tube which connects to the water pump and up to the powerhead. Is that meant to seal against the powerhead. When I removed the lower unit it dropped out. It was very loose and flopping about. I imagine there should be some kind of bung to create a seal. This would explain the overheating if so.

I also noticed that when trimming up the motor comes to far out the water and starts to rev high. I think this is due to where the boat has been repowered, the outboard is shorter and so can't come up so much. Not a deal breaker but I want to go even faster and get better fuel economy. Any suggestions for this - adding a hydrofoil? Or would trim tabs give me up trim - seems to me they only provide down trim.

Thank you all again!

Edit:

Update: Yes I checked the part manual and seems to be missing the seal.

seal.png

32 SEAL (#26-38970)


I'm assuming I just poke the seal into the hole and thats it?

[leonreno]

Sounds like the tube or seal fell out, to replace the seal if it is indeed missing, you will have to remove the powerhead to fix it. Will need some exhaust/tuner plate gaskets too. Can you post a picture with the motor level to the hull while on the trailer? Curious to see how high the motor is mounted.

[massbays]

that water tube does pull down relatively easily.
you should feel a little bit of resistance when you slide water tube up, and use grease.

[wrightjd95]

I was thinking I might be able to get away with a bigger cavitation plate. Actually I think the correct term is aspiration IE the prop is drawing surface air.

I think the seal has gone missing, damn don't tell me I need to take the powerhead off? I was thinking I could shove it up there with the pipe. I don't have a engine crane to get the powerhead off that sounds like a massive job. There is an old mexican dude who helped me last time with getting the lower unit back in, was a tricky job lining it all up. Does anybody know any tricks to get around taking the powerhead off. I even saw some dude in another form siliconed it but that is a bit too pirate for me.

Do you have a reference manual or resource that can help explain how I do that job?



Better footage coming soon!

@leonero


IMG_20210905_185727_585 (2).jpg

Best picture I have to hand is this until I get back to the dry marina. Kind of hard to see from that angle but it's not as low as I think it needs to be. Absolute beast of an outboard for a boat this size

[wrightjd95]

To confirm about the overheating, how can I easily check this? I noticed running on the muffs that the telltale was quite hot. I have no refrence for this but it was uncomfortably hot to hold my hand in, but not scolding boiling hot, bare in mind I'm in a hot climate and even sea temps are body temp. I felt it was overheating because it didn't like to idle after a fast run, to me that sounds like overheating. Could be I set my idle speed too low, but I like to err on the side of caution.