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  #1  
Old 10-06-2015, 06:45 PM
wed68 wed68 is offline
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Default Tohatsu 25 hp 2 stroke compression

I picked up a Tohatsu M25C2 today that has been sitting in the weather for awhile, price was very good so I gambled on it.

To my surprise it was not locked up and has compression and fire.

No the issue, it has 150 in top and 180 in bottom cylinder, all the research I have done online says it should only be 100 to 125 or so.

Maybe needs to be DeCarbed?
I have not pulled carb yet to try and clean and start it yet.

Any ideas on why compression is so high?

Thanks in advance
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  #2  
Old 10-06-2015, 08:21 PM
Andy C Andy C is offline
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Do you know if it was board or ported?? That will make a big difference if it has those numbers are not far off but should be closer, head gasket, rings. If your Lucky
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Old 10-06-2015, 10:31 PM
B-Stealth B-Stealth is offline
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Carbon buildup could cause the high compression. I recommend you pull the heads and inspect the cylinders ect before you start running the engine. I don't think the engine will run well with the single carb.
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  #4  
Old 10-15-2015, 02:28 PM
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CajunChristian CajunChristian is offline
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That unit usually runs about 155 pounds compression in a new motor. They run extremely well with a single carb. It was the fastest 25hp motor built in 1984 when they first arrived in the US.
I wouldn't worry about the compression just yet. Have the carb cleaned, and by cleaned, I mean by a professional, not a rinse and a promise. I use an ultrasound parts cleaner to soak the carb body and jets. After removing from the cleaner, I hose the carb down with water, then blow it dry with compressed air. There are a few trick to cleaning the carb correctly and have the engine running smooth after doing so. Those are tough little motors. The output can be bumped a little, not a lot of gain by spending tons of money. It's only 26.3 cubic inches.
D
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