Recent content by keithb7

  1. K

    Mercury 6HP "dead spot"

    The pilot jet seems to be ok, as it idles. When you open the throttle, more air enters into the cylinders via the carb. This process should draw more fuel through the carb’s main jet. The main jet could be plugged. If fuel cannot enter via the main jet the engine will stall. I’ll suggest it may...
  2. K

    4 stroke v 2 stroke. Outboard

    I believe you are correct @racerone . I have been told the ‘90 8.0 is rated at the prop. I have no proof but test results seem to support that theory as well.
  3. K

    4 stroke v 2 stroke. Outboard

    I hope it's ok to revive an old thread. I have had my hands in old two strokes recently. Re-building them. Testing them on my 3.3M SIB. Two are late 70's, one is a 1981 and another is a 1990. All two strokes 7.5, 8.0, and 9.8 hp model Mercs. My son owns a 9.8 HP 4 stroke. 2018 year. He also has...
  4. K

    1981 Mercury 7.5 2 stroke

    Following up to wrap up this thread. I had this rebuilt Merc 7.5 outboard out on the lake today. I broke it in and ran it for another 2.5 hours. It ran very well. It has 7” pitch triple prop on it. Nice and quick to get on a plane. Top speed was about 14.5 MPH. Great little engine.
  5. K

    Stubborn To Start 1979 9.8

    I feel like I finally broke thru with this 9.8. Seems like I’ve solved all the issues it thew at me. No more need to give it a shot of raw gas at initial cold start. I’ve worked on many carbs. Rebuilds, jetting, tuning. This Merc carb is super finicky. It’s running nicely now at 80 psi...
  6. K

    Stubborn To Start 1979 9.8

    Some more tinkering today. My 9.8 is running the best now, since I acquired it. Yet it still wants a raw squirt of gas when stone cold, to initial start. Researching some more. I’m thinking maybe the part that my Merc manual calls it an “idle restriction tube” is suspect. I took a spare carb...
  7. K

    Stubborn To Start 1979 9.8

    I’m all-in now. L-R: 1991 8, 1976 9.8, 1977 9.8, 1979 9.8, 1981 7.5
  8. K

    Stubborn To Start 1979 9.8

    Coming home with 2 more 9.8 Mercs must have been intimidating for this problem child. Running great this afternoon. What did I do to solve this? I’m not 100% sure. I did swap over the flywheel from the ‘74. The two appear identical. I’m not convinced that solved it. I also unbolted the 3...
  9. K

    Stubborn To Start 1979 9.8

    Ya but I’m having fun and I will beat this. Lol. The two I just picked up both measure 105 psi. Both offer lots of spare parts. Both have perfect 2 blade props. Worth the price just for the props. I also have a 7.5 that can use all the parts as well. Its a win!
  10. K

    Stubborn To Start 1979 9.8

    Well here it is, the spark easily jumping a ¾” gap. I’m laughing at this point. It’s becoming comical. I really thought we were onto something with the spark that may not jump the gap under compression conditions inside the cylinders. I have fuel in the combustion chamber I have 80 psi in both...
  11. K

    Stubborn To Start 1979 9.8

    @Nordin I think you are on to something there. Under compression the spark may not be firing. What you say makes sense and is possible. Everything else I’ve tried isn’t improving things nor computing in my head. I don’t have a spark gap tester. I have ideas to try though. I have 2 spare coils...
  12. K

    Stubborn To Start 1979 9.8

    The Ignition system looks ample to me. I need to comfirm it’s occuring at the right time. These engines are pretty basic, fool proof. I am a bigger fool than average. Lol.
  13. K

    Stubborn To Start 1979 9.8

    Reviewing my outboard technical textbooks there are 8 different Mercury ignition systems that they used. You pretty-well need to be an electrical engineer to decipher them all. Lol. Seems as the magnets pass the trigger they do their own separate induction magic and send its own separate...
  14. K

    Stubborn To Start 1979 9.8

    Tried swapping the spark plug coil wire positions. No improvement. Also coils (2 qty) tested in spec. Flywheel keyway is in place. As mentioned in my post, the cut in ‘74 flywheel magnet seen here. Wonder if this sets the trigger coil to collapse?
  15. K

    Stubborn To Start 1979 9.8

    Are you using the Choke? Yes. With or without the choke. Made no difference. If I remember, the Fuel Pump is integral to the Carb, and there are 2 brands of Carbs used on the 9.8. Did you get the correct Overhaul Kit? I think I had the right carb kit. I ran around on a local lake for 2 hours...
See more
Top