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Results 1 to 9 of 9
  1. #1

    Default 1980's 9.8hp low on power

    I have recently got hold of a 1980's 9.8hp, in very nice condition. It starts fine, runs fine but out on the water it will only make about 5-8knots on my 3.6m inflatable - it actually performs slightly worse than my 2.5hp 4 stroke!

    It looks like it has never been dismantled as the bolts on the engine block are all still painted.

    One thing I did notice was that the air intake guard is missing from the carb. When you prime the fuel, if you squeeze the primer bulb hard, fuel comes out of a hole near the intake guard mounting bolt holes.

    On the parts diagrams this hole appears to have a plug (part number 16), so might this be a cause of low power?

    I'm not sure if the plug is missing or if it is there and the fuel is leaking past it...

    There's no fuel leak when running.

    The throttle opens fully. The plugs are new.

    I will check crankcase compression and take a look under the cover over the reeds/ports.

    Anything else to check before I go further and start stripping it down?

  2. #2

    Default Re: 1980's 9.8hp low on power

    Check for spark it sounds like you might be running on one cylinder.

  3. #3

    Default Re: 1980's 9.8hp low on power

    Quote Originally Posted by flyingscott View Post
    Check for spark it sounds like you might be running on one cylinder.
    I will check that first! It doesn't sound like it's running on one pot, but then if it's never run on two since I got it, I can't say for sure.

  4. #4

    Default Re: 1980's 9.8hp low on power

    Quote Originally Posted by flyingscott View Post
    Check for spark it sounds like you might be running on one cylinder.
    Top marks Flying Scott! One of the coils is cracked... No wonder it was a bit slow!

    It didn't sound particularly lumpy or rough though.

  5. #5
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,190

    Default Re: 1980's 9.8hp low on power

    Just wait 'til she's on both cylinders! Sweet little motors.

    Jeff

  6. #6

    Default Re: 1980's 9.8hp low on power

    So I got a CDI electronics coil, part 184-0001 and although the list of coils it replaces doesn't show the orange merc coil 339-5288, it is the same size and the coil measures the same resistance.

    However, there is an earth wire on the old coil that goes to the motor case and on the CDI there is a metal strap that goes between the neg of the LT coil and the coil core.

    Have I got totally the wrong coil or do I just modify it?
    Last edited by RichardInDorset; 09-21-2017 at 07:42 AM.

  7. #7
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,190

    Default Re: 1980's 9.8hp low on power

    They work the same. (I have one of each running on my engine at the moment.) Bolt her on and see what happens.

    Jeff

  8. #8

    Default Re: 1980's 9.8hp low on power

    Quote Originally Posted by fastjeff View Post
    They work the same. (I have one of each running on my engine at the moment.) Bolt her on and see what happens.

    Jeff
    What motor do you have?

    You have one Orange Merc Coil and one black CDI coil on it?

  9. #9
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,190

    Default Re: 1980's 9.8hp low on power

    NO! I meant to say that I have two different type coils of the same color (blue). The blue and black are interchangeable, as are the red, orange, yellow and green group, but these two groups are NOT with each other.

    Jeff

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