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My F50TLRX four stroke has been idling rough. I pulled one spark plug wire at a time and discovered it was running on three cylinders. Pulling the wire on the number one cylinder didn't make a difference. I switched the plug wire from the other cylinder that shares the dual coil.. same result. I then checked the compression on the number one cylinder. It was normal. Removing the bowl drain screw revealed the number one carb was getting gas. I figured it must be one of the jets. I removed the four carbs, separated the number one carb from the four. I then disassembled this carb and removed the jets. Holding the pilot jet to the light it appeared to be plugged up. I then soaked all the parts in carb cleaner. I then cleaned all the parts up for assembly. When I held the pilot jet up to the light it appeared to have three little holes. All the pilot jets I have seen have one hole going straight through. I checked the pilot jet from two more spare carbs. The pilot jet in these were the same. Is this how these pilot jets are made? I want to verify this before putting everything back together.
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A pic would help others see what these 3 holes look like
here is the only pics I could find
Yamaha 62Y-14342-21-00 - .JET, PILOT ( 42) | Boats.net
By the way it would be best to take the carbs completely apart and clean all passages properly not just the jetsLast edited by 99yam40; 05-09-2021, 09:32 AM. -
That's the jet, but it is about impossible to take a picture of it peering down the passage. As mentioned I took the carb apart and soaked all the parts in carb cleaner.Originally posted by 99yam40 View Post
Here is what it roughly looks like when I hold it to the light and look through:
20210509_104654.jpgLast edited by ChuckB1954; 05-09-2021, 10:54 AM.Comment
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Four main jets and four pilot (idle mixture) jets. All the same part number. Should all be of the same configuration.
If one of the four is different from the other three then a backyardigan
appears to have struck again.
I have not seen all pilot jets but all that I have seen have but one hole drilled in them.
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I have came to the conclusion that it is an optical illusion. When I peer down the jet and roll it in my fingers, the circles remain in the same position. Maybe some kind of reflection. The other two jets I looked at are the same. I have never experienced this in any other pilot jet I have examined though.Originally posted by boscoe99 View PostFour main jets and four pilot (idle mixture) jets. All the same part number. Should all be of the same configuration.
If one of the four is different from the other three then a backyardigan appears to have struck again.
I have not seen all pilot jets but all that I have seen have but one hole drilled in them.
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My jet is like the one pictured in the link, but it does not have the hole on the side.Originally posted by 99yam40 View PostComment
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Put the carb back together and on the engine. Everything is good. # 1 in now contributing.Comment
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I had that thought but didn’t post as the jet had been blocked (and seen some use), the shine would have dulled inspite of sitting in cleaning solution.Originally posted by ChuckB1954 View PostComment
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I put everything back together after cleaning the #1 carb thoroughly. Engine idled great including the #1 cylinder. I hooked up the vacuum gauges and digital tach and tuned the carbs. It was as good as it ever ran. I drained out the old gas from the onboard tank, which appeared to be fine, and replaced it with new rec fuel. I took the boat out and everything was fine, but at the end of the day the engine was shaking again at idle. Pulling the number one plug wire revealed the same problem. I am thinking that it is time to replace all the rubber lines. Maybe they are starting to deteriorate(?) The only question, why is it only the # 1 carb??
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One thing I did notice.. The #1 carb is the only carb that has a curved line going to it (#19). Maybe this line is bad?
Curved.JPGLast edited by ChuckB1954; 06-18-2021, 01:30 PM.Comment
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