Thanks for the quick reply!
Good thoughts and yes, I bought the engine used with 325 hours. Looked like new engine but has always ran a little rough (had a Johnson 175 2-stk for 15 years which was noticeably smoother). Changed fuel pumps which seemed to help a little and checked plugs with timing light. The needle valves definitely not seating on the lower two carbs. Nice that the upper carb is not leaking so I know the problem can be rectified. Both needle points and seats seemed ok but now I know what to do and, hopefully, I'll get a smooth running engine. Thanks again - Al
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Are you the original owner?
Strange that the floats were all too high by roughly the same amount. Sounds as if someone might have tweaked them beyond specifications trying to get the valve to close. You set them to spec of course and maybe now they leak.
If this is the case I would suspect the needle valve to be the issue.
Was the engine running rough at idle or at power?Leave a comment:
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check your manual to see if gasket is not in with the measurement, and replace the needle and seat if it will not close off the fuel when pumping the bulbLeave a comment:
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Yamaha 150 TXRC carb float question
Good Morning- My engine is a 2004 Yamaha 150 TXRC. Engine has been running rough. Removed carbs (3). Real clean from Dunk's method and regular use of Ring-tight. However, Yamaha manual for the engine states to adjust carb float level to 0.63" +/- 0.02". All three floats were between 0.68"-0.74". Dutifully bent tab under the needle valves till all three floats measured 0.63" (with gasket removed). Checked that needle valve & seat were in good shape and that float worked cleanly. Re-installed carbs and primed. Had gas dribble out from the top front of lower two carbs. I suspect that the floats should have been kept at 0.72" but that's quite a difference from the manual. It took just a moderate pressure from the priming bulb to get the gas to flow out the top front of the two carbs, Any help would be greatly appreciated. - Al
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