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  1. R

    2007 40hp Merc carb and compression questions

    I should’ve probably stated that I’m trying to sell the motor and I wanted to make sure the I’m not screwing anyone over with the compression. Sounds like I’m good.
  2. R

    2007 40hp Merc carb and compression questions

    Good point. Thanks to everyone for their help.
  3. R

    2007 40hp Merc carb and compression questions

    Your assumption is correct 😂 It just seems strange that I am reading much closer to the 120 mark than the 87 mark, and I’m just trying to figure out why that would be. Doesn’t that seem strange that I would be much higher than the rated compression?
  4. R

    2007 40hp Merc carb and compression questions

    Thanks a bunch. I wonder if my motor is the equivalent to the 40BTR (120psi), rather than the 40BMH? Did your research of my serial number line it up with the BMH?
  5. R

    2007 40hp Merc carb and compression questions

    Wow, so this 4-stroke mercury was manufactured by Yamaha? I had no idea they did that. Are you 100% sure on that compression? Because the compression went from way too low to way too high. Or maybe more likely my new gauges are incorrect. I noticed the other compression setting on your spec...
  6. R

    2007 40hp Merc carb and compression questions

    Serial number is 1C050911. I heated it up first, removed all plugs, WOT, then pulled 8 or 9 times until it quit going up (pull start). I just bought the gauges at Oreillys but they are not “top shelf”.
  7. R

    2007 40hp Merc carb and compression questions

    I hooked my comp tester gauge to my air compressor at 150psi and it reads about 135psi so it may be off just a bit, but not a lot. Using that as a correction factor, I’m coming up with 115 125 and 130 ish.
  8. R

    2007 40hp Merc carb and compression questions

    Would someone mind checking a service manual for that carbureted motor? I would sure appreciate it.
  9. R

    2007 40hp Merc carb and compression questions

    Well that’s not good…
  10. R

    2007 40hp Merc carb and compression questions

    Thanks. I hadn’t looked into it. I can rebuild a carb but going into the cylinder head is above my pay grade. I thought that within 15% from the high to the low was acceptable.
  11. R

    2007 40hp Merc carb and compression questions

    I just bought a 2007 mercury 40hp 4 stroke. Rebuilt the 3 carbs and it starts and runs good but it’s a little smoky. I left the mixture needle screws where they were at. Can someone tell me what the proper setting is for this screw on each carb? How many turns from tight? I used to my old...
  12. R

    1998 25hp Johnson water circulation issue

    Howdy, I've got a 1998 Johnson 25hp (J25TELE). It has ran great for a long time. I've run this motor for almost 13 years. Today I put it in the water and checked the pee stream like always and it was normal. However, the motor sounded a little different. Couldn't put a finger on it. I noticed...
  13. R

    25 hp Johnson starter switch

    I'm looking at a starter switch on ebay. It's part number 394020. The starter switch on my 1998 25 hp Johnson is p/n 583925. Can someone tell me if this starter switch and harness will work on my motor? The one on ebay looks good, but it looks like it is for a 50 hp, and the leads are 3'...
  14. R

    25 horse caught fire!

    I've got a 98 model 25 hp 2 cylinder electric start tiller motor. Yesterday I backed it in the water and pushed the starter button and the button didn't reset - it stayed depressed. I then saw that the bare ground "cable" that goes from one of the starter bracket nuts to the screw by the gas...
  15. R

    10"x11 Power Tech Spun....replace or rebuild?

    Hi all, I've not had any trouble out of this prop over the last 10 years until now. I've got a 10x11 SS Power Tech on my 25 HP Johnson. I've spun it and I need to know the best course of action... Should I get it repaired, or replace it? The prop itself is in pretty good shape as far as I...
  16. R

    changed seals, pressure tested, still milky - '98 25 hp Johnson

    Aight, last month I noticed my LU oil was slightly water-tinged, so I decided to go ahead and change the seals. While I was at it, I changed the 2 prop shaft bearings and the top bearing on the drive shaft. Anyway, all the seals, gaskets and o-rings were changed. I went out yesterday and...
  17. R

    Has anyone used....

    ...Advanced Marine for ordering parts/lower unit work? I found them on ebay. They're located in Interlochen, MI. Bought a used bearing carrier from them. I called several times and talked to the owner - Joe. He seemed very knowledgable and helpful. Just wondering if anyone else has dealt...
  18. R

    Lower unit plug washer - 98 johnson25 horse

    Hi, there's no dealer anywhere around here and I "misplaced" one of the nylon washers for the drain plug on the lower unit. Can I just go down to the hardware store (lowes) and grab a bag of 'em? Are they the same? Thanks.
  19. R

    Detent spring question

    Putting my LU back together on my '98 25 horse... How in the heck do I get the detent balls and spring on the prop shaft back into the clutch dog without the "special OMC tool" prescribed in my manual. Is there another way? Also, I presume the balls fit into the groove in the middle of the...
  20. R

    '98 Johnson 25 hp pivot pin screw stripped

    Hi, I've got a huge problem. In the process of putting new seals in my lower unit, I stripped the hole where the pivot pin screws in the side of the LU. It has (had) about a 1/4" of threads in the alum housing and now it's completely stripped. Any pointers? Is a 1/4" hole depth enough for a...
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