2003 125hp 2 stroke 2x2 question

[WisconsinF]

2003 Merc 125hp 2x2 2 stroke .
Serial #0T745549 (Tracker Branded)

Now that I'm retired and have plenty of time to "get at things" I'm wondering what it would take to jet the carbs that do not have the low speed jets in them.
Has anyone done this and what were the results?
Is it worth doing?

1...If I jet those carbs will warm starts be easier.?..(currently likes to argue with me some) Will it idle smoother? I know the 2000 rpm stumble will go away.
2...What 2 carbs are NOT jetted...Bottom 2? Top 2?
3...What parts would be needed to jet the 2 non-jetted carbs?

Thanks in advance...
WiscoF

[06 SB]

I had a 2004 115 2+2. I never had a problem with warm starts. It was the cold starts for me. In either case, having the motor perfectly vertical helped. It was not bad though. My suggestion would be to do a thorough decarb then replace the spark plugs (properly gapped) and run a healthy dose if Quickclean in every tank. Also, do a proper link & sync to make sure everything is working properly together.

As far as replacing the carbs, I cannot help you there. I would think just buying a new motor would be an easier option. Parts for a 20 year old motor have to be getting scarce.

[JOE54]

try this squeeze bulb until firm then try to burst bulb times key on hold choke in small amount of throttle and spin it , DO NOT BE MESSING WITH THOSE JETS first of all it wont idle down if you introduce fuel into bottom cyls , leave it alone get it set up right

[06 SB]

Another thought that has not come up in a while. Have you ever replaced the original fuel lines. Those from 2003 were usually not ethanol resistant and may be breaking down internally.

[WisconsinF]

OP here....I've put this idea of jetting the non-jet carbs on the back burner for now.
Besides the current warm start / idle problems I've got a car that just had an expensive repair and decided to turn into the Exxon Valdez.
Got to prioritize I guess. Let's get the car back to the shop and work on just curing the current Merc engine woes.

My dad always said if it's got boobs or wheels it's going to give you trouble...add "boats" to that

[EuropeanAM]

Just out of curiousity- what do you have the idle air screws set at for the two top carbs? With today's fuels, these often do much better (overall) with 1/8 - 1/4 turn COUNTER-CLOCKWISE from original setting.

[WisconsinF]

Hey Don…thanks for reaching out. I’ve owned this rig for 7 years and have never touched the carbs. Have just lived with the idle situation and worked around it. Pretty sure everything is at factory settings. Next time I’m on the water I’ll see where the idle air screws are at and report back.
Thanks again…
Barry

Just out of curiousity- what do you have the idle air screws set at for the two top carbs? With today's fuels, these often do much better (overall) with 1/8 - 1/4 turn COUNTER-CLOCKWISE from original setting.

[WisconsinF]

Confirming that #24 is the Idle Air Screw?
Thank you.

Idle Air Screw.JPG

[WisconsinF]

Parts listing has #24 as the Idle Air Screw....just confirming.
Sorry...double post

Idle Air Screw.JPG

[JOE54]

those are air adjustments

[EuropeanAM]

[WisconsinF]

Thank you Gentlemen!

[Slicefixer]

try this squeeze bulb until firm then try to burst bulb times key on hold choke in small amount of throttle and spin it , DO NOT BE MESSING WITH THOSE JETS first of all it wont idle down if you introduce fuel into bottom cyls , leave it alone get it set up right

^^^^^^T H I S^^^^^^^

I have the exact same engine and the same engine in a 115 prior to my 125. I did hours of research, including listening to Mr Joe and a couple of other true Mercury experts in regards to this engine. They ALL said do NOT screw with the original design.

Cold start procedure I was taught by these guys.... warm starts aren't any issue.

- Pump your bubble until it's hard as a rock..... then a couple more times.

- Open the throttle slightly....

- Choke it 8 it 10 times.....

If your engine is in his shape (good fuel) she should fire right up.... both my 115 and 125's did/ do.

[JOE54]

most dont know that there are 2 check valves /injectors on stb side of block threaded into transfer ports when bulb is squeezed vey hard after its firm you are spraying fue almost on top of piston or right beside it when crank spins its instant explosion in combustion chamber , we have lift off , dont believe me squeeze it after it starts watch it rev up

[Slicefixer]

most dont know that there are 2 check valves /injectors on stb side of block threaded into transfer ports when bulb is squeezed vey hard after its firm you are spraying fue almost on top of piston or right beside it when crank spins its instant explosion in combustion chamber , we have lift off , dont believe me squeeze it after it starts watch it rev up

Thank you Mr Joe! I stand corrected by a man that really knows what he's doing...👍 i will now eliminate my extra squeezes.... hehehe. I was in Longview for a funeral recently and forgot to locate and thank you. The next time I won't be so forgetful!

[JOE54]

no dont thats what helps it start so easy

[WisconsinF]

UPDATE...(insert breaking news music here)...

1.Yesterday I removed the fuel tank and completely drained it of 10% alcohol fuel with additives then reinstalled the tank and put in 10 gallons NON-alcohol gas with no additives
2. Backed out the idle air screws 1/4 turn.

Went to the launch this morning and performed the tried and true cold start procedure that had always worked great for me HOWEVER once the motor would fire I had to hit the enrichener a few times and play with the throttle to keep her running. But this morning she fired right up and settled into a nice idle without having to fidget with anything. Ran up river a few miles to warm it up then stopped to fish a few banks..... restart after about 15 minutes was great...pump bulb, just a tad of throttle and she fired up without any stumbles and settled right away into a smooth idle....I've never had such a smooth "warm start"!!!


I had purchased a can of Mercury Power Tune and went ahead and did the decarbonization. This seemed to even help more.

So I have to say I'm incredibly happy and I think the biggest improvement for this situation was Don's tip to back out those idle screws. But making sure all the system components are 100% good and working correctly is really important.

One thing I forgot to mention is that I fixed the bulb so it is always vertical (arrow pointing up). Huge improvement and it's like a big hit of Viagra....literally stays hard for days and just the slightest squeeze puts it back to very firm.

and I did rebuild the fuel pump just for good measure.

Thanks everyone for the help!!

[Slicefixer]

no dont thats what helps it start so easy

That's what I thought...👍 I obviously misunderstood your message. Thank you!

[Slicefixer]

UPDATE...(insert breaking news music here)...

1.Yesterday I removed the fuel tank and completely drained it of 10% alcohol fuel with additives then reinstalled the tank and put in 10 gallons NON-alcohol gas with no additives
2. Backed out the idle air screws 1/4 turn.

Went to the launch this morning and performed the tried and true cold start procedure that had always worked great for me HOWEVER once the motor would fire I had to hit the enrichener a few times and play with the throttle to keep her running. But this morning she fired right up and settled into a nice idle without having to fidget with anything. Ran up river a few miles to warm it up then stopped to fish a few banks..... restart after about 15 minutes was great...pump bulb, just a tad of throttle and she fired up without any stumbles and settled right away into a smooth idle....I've never had such a smooth "warm start"!!!


I had purchased a can of Mercury Power Tune and went ahead and did the decarbonization. This seemed to even help more.

So I have to say I'm incredibly happy and I think the biggest improvement for this situation was Don's tip to back out those idle screws. But making sure all the system components are 100% good and working correctly is really important.

One thing I forgot to mention is that I fixed the bulb so it is always vertical (arrow pointing up). Huge improvement and it's like a big hit of Viagra....literally stays hard for days and just the slightest squeeze puts it back to very firm.

and I did rebuild the fuel pump just for good measure.

Thanks everyone for the help!!

👊😉👍