Neptune Mighty Mite won’t run in water

[pwpearce]

I am trying to get a new to me neptune mighty might running. It wouldn’t start in water. I tested the spark with an inline tester on a stand out of water and by surprise, it started. I shut it down immediately. Put back in the water it wouldn’t start.
I raised the exhaust vent out of the water and it started- lowered into the water while running, it stalls. Is this a compression issue? reeds? I saw something about that on this forum but don’t know my next step.
I’m new to the forum. I also have a small Seagull that purrs right along.
Thanks Paul

[bobprock4200]

That’s usually a sign of low compression. Although, there’s not a whole lot there to begin with anyway, but does the flywheel "bounce" back a little when you turn it over by hand or does it just go around with little resistance? You might be lucky have have stuck/gummed up rings which with a little cleaning should spring back, worst case would be worn rings and cylinder, but usually most Mighty Mites sit more than they are run so perhaps the former will be the case. There’s enough "oomph" to get it running, but once the prop hits the resistance of the water there’s not enough strength to keep it going. BUT, they’re simple to take apart and check, Doug Penn pennitgo.com has quite a bit of resources for Mighty Mites. Good Luck!

[pwpearce]

Bob,
Thanks for your quick response. The flywheel has a lot of bounce. When I get it running by tilting the exhaust vent out of the water it appears to have a lot of power – the prop kicks up lots of water. When I lower the exhaust vent below the water it runs for a few seconds before dying.
I did find Doug’s site, thanks. I’m not giving up. I’m setting this aside and getting the Seagull out to put on my canoe this weekend.
Paul

[frankr]

Reeds might be a good guess, if it isn’t compression or worn out crank bearings.

[slim60]

A member suggested this to me last year. After you check everything these guy mentioned, try running it without a prop. Run for a minute, shut down for ten, and do it again until you are satisfied with it’s performance. Then try running with the prop. Good Luck!

[reivertom]

Could it be a head gasket leaking water into the cylinder?

[Author]

Posts