Strange Fleetwin

[chris-p]

I almost feel like a rookie here.

I built a ’55 Fleetwin from parts.

Compression is good, 85 psi on both.

All new ignition. Strong spark on both cylinders.

Full fuel system rebuild. Still running on pressure tank.

I sold it to a local fisherman to put around with. I only ran it in the test barrel briefly before he came by. I admit, did not high speed run it in the barrel, my bad.

Anyways, he tells me that it has no top end power. I told him to bring it back and I would have a looksee. Figured something silly.

He is right though. You rev it up, and no power. Almost like its running on one cylinder, but its running on both. Watched spark on neon tester while holding it wide open, and consistent spark.

Went through carb again, and rebuilt it all over. Same issue.

Opened exhaust, thought might be clogged, but no issues there. Installed new gasket and closed it back up.

Almost seems like water getting in cylinder. Did not replace head gasket, but with good compression, didn’t think that was it.

Any thoughts. I should have measured the shock absorber before installing it, but that is all that I can think of that would be causing this, if the spring went on it, and causing friction?

You would think the gears are off on the tiller, as Fast acts like start, start acts like slow, etc….

Stumped in Hamilton.

[retiredoz]

Well, assuming your mag and throttle advance are operating properly, I’d say the shock absorber is a fair bet.

[chris-p]

I can usually feel that when I use my timing fixture. I can usually feel a bad one rotating crank with plugs out. This doesn’t feel that bad, to slow the motor this much……All I can think of though. That or water, which I haven’t totally ruled out yet.

[beerman57]

What about plug wires grounding on the mag plate, I had that problem. Easy test, just touch the mag plate while it’s running and you’re grounded!

[chris-p]

Don’t think so. All brand new ignition and wires. Strong spark thoughout all ranges, even when "bogging" at WOT. Ill have the wife do the test though 😉

Linc n sync set.

Another possibility……as I said, I put this together 1 piece at a time from individual parts boxes. I may have used an incorrect cam, mag plate, etc…. ill have to think about that.

[frankr]

Is it actually rotating the mag plate to full advance position? I ask because of what your said, start = slow, stuff like that. Check throttle gears matching and check for twisted vertical throttle shaft and/or the nubs worn off the bottom of it.

[Steve A W]

The vertical linkage shaft was bent on my 18hp Johnson when
I got it and it acted like that.

Steve A W

Member of the MOB chapter.
I live in Northwest Indiana

[wick83]

Just because it’s getting fire at the plug wire doesn’t mean it’s fireing, I know confusing right. I’ll explain, would you be able to briefly pull out the plugs immediately after running the motor? Sometimes is what causes this problem is if the head gasket is leaking on the cylinder side "inner edge" which allows water to be pumped into the combustion chamber. And we all know we put on fire to put it out. Always start simple before spending $

[wick83]

I forgot to ad the reason for pulling the plugs, you’ll be looking for water on the end of the plugs and possibly even a noticeable difference in temp between the two. But as you do this make sure to take note on which plug was in each cyl

[jeff-register]

I know to save money I have cleaned the surfaces, added sealer & tried to use the old head gasket. I never had the results of a plain new head gasket. I would suggest the figure 8 sanding & a new head gasket. Pulling the plugs will show two different results & they should be the same, sorry to bring bad news.

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