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TOPIC: Bearcat 55 - Cracked Block???

Bearcat 55 - Cracked Block??? 3 years 1 month ago #107012

  • Driller
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Hello fellow Bearcatters,
I've had some issues with one of the Bearcats I run as a set of twins on a Boston Whaler. After running wide open for a minute or two, I lose power and the motor cuts down to about half speed. If I back off the throttle, it'll run fine at about 1500 to 2000 all day. After a few minutes, I can run it wide open again but only for about a minute before it cuts down again. I can do this all day, and it'll idle nicely all day.

I've rebuilt the carbs twice, including the accelerator pumps, replaced the original fuel pump with a modern pump from Bill R., I've switched gas tanks, hoses, primer bulbs etc. with the other motor (which doesn't have the same issue, ever). I put in fresh points and condensers, even changed the coil, all with no change. Once or twice, while holding the throttle wide open while the problem was happening I got a pop or two out of one of the carbs indicating a lean condition. Thinking it was the lower carb I pulled the lower two plugs and they were absolutely spotless after 10 hours of running - and I mean out-of-the-box clean. The upper plugs were a nice chocolate brown. I guess I could have missed on a float level adjustment after two rebuilds but I'm sure I would have noticed anything out of the ordinary.

I'm wondering if maybe I have a cracked block and the steam or water in the lower cylinders is cleaning those plugs? Does that sound like a possible scenario to anyone? Could this be caused by a valve adjustment issue? Just a hunch but I'm baffled. My last possible idea is to pull carbs from one of my other Bearcats, clean them up and put them on the problem motor to see if the problem persists. If that doesn't work, I'm afraid this motor will be relegated to the parts motor pile which is now numbering somewhere around 8 Bearcats and Homelites. I have another Bearcat or two that will probably run with a little cleaning up but I hate to take such an otherwise great running motor out of service - and the ice is melting and the salmon aren't going to wait.

Any input would be appreciated. Thanks!

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Re: Bearcat 55 - Cracked Block??? 3 years 1 month ago #107235

  • billr
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it sounds like fuel problem in the lower carb to me.
i do not see many cracked blocks, and water intrusion would likely affect the lower rpm, in addition to higher rpm problem you are describing.

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Re:Bearcat 55 - Cracked Block??? 3 years 1 month ago #107253

It would be a bit of work but maybe you might switch both carbs form one engine to the other.

Greg Anderson
Wisconsin

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Re:Bearcat 55 - Cracked Block??? 3 years 1 month ago #107259

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Yes, I originally thought it was a lean condition in the lower carb, that's why I pulled them apart a couple of times, and I guess it still seems that could be the case. When I get the snow off of everything, I will switch carbs from one of the other motors and see if there is any change.

The cracked block idea came about because of the condition of the lower plugs - particularly the number one plug, after 10 hours of running it really looked as if it just came out of the box, no color at all, white, brown or black. We still have ice out here but I want to be out on Lakes Champlain and Ontario by mid April for some of those 15 lb brown trout - can't wait to hear those twins harmonizing again!

Thanks for the replies!

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Re:Bearcat 55 - Cracked Block??? 2 years 9 months ago #111852

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Well I finally finished the Outrage 21. I put two different carbs on the problem motor, pulled them from a dead motor, cleaned them up and splashed the boat for a test run today. Both motors ran flawlessly, no bogging after 20 minutes of hard running. I may be a bit underpropped but that's no big deal, I have other props. I just cant figure how I could have missed a carb issue after so carefully cleaning and rebuilding those first carbs several times - maybe a bad float? Who knows, I'm just happy to have the twins back in action. I hope to post some pictures soon, the motors look great on the vintage whaler.

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Re:Bearcat 55 - Cracked Block??? 2 years 9 months ago #111933

Glad to hear you're up and running.

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