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  1. Plandeck

    8hp starts but runs only at high rpms

    Its a fair point about the over heating. The tell tale was always less than impressive and after the overhaul is now much stronger. I noticed corrosion around the thermostat and now regret that i didn't change it.
  2. Plandeck

    8hp starts but runs only at high rpms

    Sorry to disappoint all you ultrasonic carb freaks but, dissembling the head a 2nd time and spending the $75 having it shaved improved the compression, not by much, bet enough to get her to run at low rpm. The head was slightly warped transversally so head gasket (between pistons my guess)...
  3. Plandeck

    8hp starts but runs only at high rpms

    What could be the electrical prob? Seems like timing is stuck in advance. I replaced 2 coils and solenoid in the past. I do have a 2nd carb which i think i already tried...but ill try it one more time before i run out a buy an ultrasonic. At least she's running. Overhaul may have been...
  4. Plandeck

    8hp starts but runs only at high rpms

    Well she's bolted back together and started right up....but same problem. She dies at less than 4,000 rpm. Compression measures the same around 70. Not sure what else I can do. Plan to soak the carburetor one more time over night, but other than that its order a new 15hp outboard online and...
  5. Plandeck

    8hp starts but runs only at high rpms

    I did deglaze but knew nothing about the ridge. Besides that, there is a small tilt across the top of the valve side of the block at the center between the two pistons...maybe 1mm. (see photo). Could explain low compression? Or is the piston cylinder designed to be slightly higher so it will...
  6. Plandeck

    8hp starts but runs only at high rpms

    Ok piston rings replaced and new head gasket ready to install...not sure about setting the timing belt. I marked TBC on both timing gears during dissembly...how can I make sure I've got the two timing gears properly aligned?
  7. Plandeck

    8hp starts but runs only at high rpms

    Of course I don't have a lot of experience with the feeler gauge, but end gap and side gap seem well withing tolerances. Even bore dimension at top seems smaller diameter than manual calls for 2.14 instead of 2.16.
  8. Plandeck

    8hp starts but runs only at high rpms

    Rings and head gasket are ordered. I don't see cross hatching on the bores difficult to photo bores...some discoloration and wear visible but no scratces. They are glazed. Rings are ordered and rebore is not practical. Plan is to slap in rings (with or without hone) and reassemble. May be...
  9. Plandeck

    8hp starts but runs only at high rpms

    no carbon deposits on pistons only minimal on tops No carbon in ring grooves only minimal on tops
  10. Plandeck

    8hp starts but runs only at high rpms

    What about honing the piston bores? Look pretty clean to me. No scores only some discoloration at the top and the glazing the manual talks about. Afraid of scratching them if i try honing.
  11. Plandeck

    8hp starts but runs only at high rpms

    Test on the valves was blowimg into the ports...all air tight. Those little springs look look a ***** to compress to relese the valve stem...would like to do a "back yard" valve job with a little valve polish and an electric drill but worried about getting it all back together. Springs no...
  12. Plandeck

    8hp starts but runs only at high rpms

    heres what the valves look like...are those inlet valves abnormally darkened?
  13. Plandeck

    8hp starts but runs only at high rpms

    luckily 100% fresh water - lake Michigan.
  14. Plandeck

    8hp starts but runs only at high rpms

    well, I ran the compression test with throttle wide open...maybe an improvement of 5psi to 75psi on each cylinder. So I pulled the power unit and its sitting on my work bench. I will order a set of rings and a head gasket working on the presumption the rings are warn. I did test the rocker...
  15. Plandeck

    8hp starts but runs only at high rpms

    Thank you for your reply. It is a 4-stroke. I've done the compression test twice once with the engine cold (70psi) and once warm (60psi). I admit I did forget to open the throttle. Checking valve clearance was my next move. It may be a bit difficult because motor is still mounted on the...
  16. Plandeck

    8hp starts but runs only at high rpms

    Compression measured in at identical 70psi for both cylinders. Seloc manual says they should be 128psi. Oil added to each cylinder before testing increased psi in one cylinder by 5-10psi and saw no change in the other cylinder. However, introducing oil into spark plug hole was difficult since...
  17. Plandeck

    8hp starts but runs only at high rpms

    Sorry to confound all the experts...the carburetor soaked overnight in OMC cleaning fluid still won't run unless rpms are 4,000+. As a note soaking the o-ring around the high rpm jet screw made it balloon and it had to be replaced - luckily still had the old 8hp carburetor (believe I bought the...
  18. Plandeck

    8hp starts but runs only at high rpms

    Do you know what size compression tester I would need? 14mm or 18mm? And if it is compression does this mean new rings, rebore or what? Thanks!
  19. Plandeck

    8hp starts but runs only at high rpms

    My 8hp 2007 Nissan outboard starts but runs only at high rpms. It dies when throttle is decreased. She ran fine the first day in the water, but after an hour of high rpm boating she would not idle without dying. Any suggestions?
  20. Plandeck

    Starter cranks intermittantly

    8hp Nissan outboard model NSF8A2 EF2 with key start sometimes cranks and sometimes clicks. Does this mean the starter is failing and should be replaced or rebuilt? Any other cures or trouble shoot ideas? Thanks!
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