How to thoroughly clean our Yamaha 25 hp outboard carburetor? What is the best carb cleaner to use?
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M$1 Answer
The Yamaha 25HP Outboard motor has been made in both 2 and 4 stroke versions. The 2 stroke gas has extra oil in it which a four stroke does not need. The Carb cleaner will try to remove this extra oil. Do not run the engine at all with carb cleaner. Instead soak the carburetor in Carb cleaner overnight and the blow it out with compressed air. Then reassemble and start with your regular gas.
Adding an additive like Seafoam to the gas before putting it in the engine will help to keep the effects of the ethanol from varnishing the engine from the inside. The ethanol strips the protective oil from the inside of the cylinder walls. Ethanol burns hotter too.
Chemtool B12 is a carb cleaner (they also make fuel additives) and is widely available in San Francisco and other US states. It does contain acetone so please take care when working with it. Use it outside.
Here is a video on cleaning a Yamaha 115HP carb. It is a bigger unit but hopefully still useful to you.
http://www.youtube.com/watch?v=wV4T-_oRllE&feature=related
Here's a three part video on how to clean your Carb. (Its for a car)
http://www.youtube.com/watch?v=Aidv4e-KYIM&feature=related
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M$
Good work. Our 25AMH is the 4-stroke model.
Thanks for the Seafoam tip. We did fairly extensive research on the best additive for ethanol-contaminated fuel -- the votes were very heavily for Sta-Bil Marine Formula “ethanol treatment” 1 oz per 5 USgal dilution. We treated all our fuel with that before sailing out of San Francisco end June 2009. It is impossible to know how bad our fuel system would have been WITHOUT the Sta-Bil in New Caledonia September 2009 -- we just know it was the worst we have ever seen (this was our first encounter with "evil ethanol".)
Chemtool B12 is the carb cleaner that I've turned up as the favored pick in this week's web research. It does not seem to be available in NZ. Key ingredients seem to be acetone and MEK (both of which we carry). In New Caledonia it was acetone on the third tear-down & clean that finally got enough of the gunk out to get the engine going. After an overnight soak in the acetone.
"Do not run the engine at all with carb cleaner"
Why is that a bad thing for a 4 stroke?
I was hoping there was an aerosol carb cleaner that we could use as a preventive to keep the carburetor clean - avoiding the need to do a tear-down. I.e., start the engine, then spray cleaner in the air intake. E.g., the Berryman B-12 Chemtool Carburetor Choke Cleaner Part Numbers: 0101, 0105, 0116, 0155 (Blend 1AA-MS)
Is that a bad idea?
I think you can use carb cleaner to flush 4strokes but its not recommended for 2 strokes. They need the oil for lubrication - but not relevant for your case.
Other brands that work well and might be in NZ are:
- 3M CHoke and Carb Cleaner which is an aerosol spray and may be better suited as its a good in-place cleaner.
- In New Zealand I believe Wynn's carb cleaner is available.
- CRC Clean-r-Carb also a good in-place cleaner. I suggest this one
http://www.crc.co.nz/frame_prod.asp?pid=112