Bunch of questions! Merc I4 90hp-125hp

**speedaholic** · 01-12-2023, 09:24 PM

So its not a 2+2 motor? Frankly if its a 115 or a 125 im thrilled. I paid $450 for the boat, motor, and trailer. Heck the trailer is probably 90's but its galvanized and in nice shape. Dont need it so I can probably recoup $400 or maybe more for the trailer. I did the compression test when it was cold and dry. Hadnt run since 2019. All 4 holes were between 136 and 140 psi with the throttle at idle. Far as im concerned im golden. When all is said and done I will have $100 in the motor. How can I go wrong!

**James45157** · 01-12-2023, 09:33 PM

they also made a 100 hp 1989 had one on a new searey boat never really cared for it it was a strong motor but very hard to keep tuned lean idle spit dont turn them over 5200 rpm as number 3 rod will go very fast we had a few that was proped wrong and number 3 rod would go out the side or crank would turn blue mercury told us that for some reason number did not get oil when rpm when over 5200 they are a long stroke motor good luck keep the rpm at 5200 should run a long time

**cali kid** · 01-13-2023, 07:35 AM

Originally Posted by speedaholic

So its not a 2+2 motor? Frankly if its a 115 or a 125 im thrilled. I paid $450 for the boat, motor, and trailer. Heck the trailer is probably 90's but its galvanized and in nice shape. Dont need it so I can probably recoup $400 or maybe more for the trailer. I did the compression test when it was cold and dry. Hadnt run since 2019. All 4 holes were between 136 and 140 psi with the throttle at idle. Far as im concerned im golden. When all is said and done I will have $100 in the motor. How can I go wrong!

It's a 2+2 motor for sure.

**speedaholic** · 01-13-2023, 12:50 PM

Not sure if im happy or not about the 2+2 thing. I never knew it existed. Does anyone know if when I test for spark only 2 plugs will get spark? I guess it doesnt matter. I will run it till it dies!

**cali kid** · 01-13-2023, 12:59 PM

It will have spark on all 4. The 2+2 is in the carbs.

**BrononC** · 01-13-2023, 02:45 PM

You can find 2 top carbs with idle circuits and put them on the bottom and it will idle on all 4.

**James45157** · 01-13-2023, 10:55 PM

the way mercury told us that at idle the 2 carbs put in enoug fuel air mixiure so they do fire so that they dont drag the other 2 cylinders if you look there is a small pump that puts fuel in so you can get the boat on plane

**rock** · 01-14-2023, 11:04 AM

Will it actually idle under 2000 rpm if you put idle circuit carbs on bottom 2 cylinders

Rock

**BrononC** · 01-14-2023, 12:16 PM

A local mechanic here has done them before, he has even drilled the circuits out and add a mixture screw to the bottom carbs. My buddy had a 2+2 with a tiller handle and we were supposed to do it on his because we couldnt get the transition from 2cyl to 4 cly smooth enough, it was aggravating to drive with a tiller especially in smaller bayous where you weren't turning much rpms. He ended up selling the rig before we could do it. My mechanic that has done a few before did say they idle pretty radical tho on all 4

**speedaholic** · 01-14-2023, 01:11 PM

Well if its good enough for mercury it will be fine for me! Im not gonna mess with it unless I have to. This motor is going on a bass boat I picked up. Its an 86' Laser that was a drag boat since new. Its never been rigged to fish. I wanted more motor but im poor lately and working with a budget. It will definately be the slowest this boat has ever run.

**rock** · 01-14-2023, 01:15 PM

I was told that they could not get the motor to idle under 2000 and that is why they killed the bottom two holes. I have had a couple and they are not bad motors but they can be a bit finicky. Maybe not a screamer but gonna be a nice set-up when complete. Congrats.

Rock

**Jim Speros** · 01-14-2023, 05:25 PM

I agree. It can be finicky to adjust. Most cases complaints come after someone has jacked with them. It will idle well on two and if the linkage is set right it jumps right up on plane.

**DanUmbarger** · 01-14-2023, 07:37 PM

I have a 115 2+2 on my pontoon and it runs great. I thought the bottom 2 carbs were the non adjustable carbs but his pics show low speed needles on the bottom cyls and we can't see what is on the top 2 carbs. As for the lean sneezing I have had to clean the bleed check valves (behind the electrical plate) and stretch the small springs some which cleaned up all the sneezing on my motor. Really like how low and smooth it idles.