Tweet
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
-
-
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 bulb -
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?Comment
-
gasket is installed when measuring the float height.Comment
-
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 - AlComment
-
then why don't you set the floats correctly.
with the gasket installed ?????Comment
-
Actually, my Yamaha manual for this engine is very specific. Page 4-18: 'Measure float height (a) without the gasket'. Sure appreciate your comments. - AlComment
-
Comment
-
Thanks for the pic, seems we have the same manual. I've also heard that the float should be about level as it is shown in the pic. All mine are were pretty level after setting for the 0.63" setting. Removed all three carbs. Turned each carb upside-down (seal orifice by gravity) and put Mityvac on fuel inlet tube. #1 carb held pressure fine (10 psi). #2 and #3 held no pressure at all. Worked on #3 first: Cleaned needle valves and seats (just wiped clean) and inspected needle points & seats with magnifying glass. Looked fine and reassembled. Held pressure @10 psig fine. Will do same to #2 and, if correctable, replace carbs and try again. Weird thing: #2 initially held pressure but after moving it a bit before opening it up, it totally failed. Find out more when I open it up. - AlComment
-
Al? Al Nibecker of the Big Island?
You be da kine man. Mahalo.
Bookem danno, murder one.
Boscoe99, formerly known as "you f_cking haole".
When asked if I wanted a broke ass, or what? I said I wanted the "or what" thinking it could not be worse than a broke ass.Comment
-
defiantly did not follow that last post completelyComment
-
You would have to have lived in the islands. Al will know what I am talking about.Comment
-
trust me, set the floats with the gasket in place.Comment
-
I have the same engine and its runs great at all speeds except idle...
Is there anyway to pull the jet out and clean and re install without pulling the carbs off all together?
And if so can someone please send me in the right direction and where that idle jet is located on the carb?
I have done motorcycle carbs but they are always under the float and it had to be taken apart..
Thanks
DanComment
-
What's wrong with the setting to his manual (without gasket) after he fixes the leaking needle and seat?Originally posted by rodbolt17 View PostComment
Comment