Carb leak help

[tex_waco_usmc]

ok, someone help me figure out what I’ve done wrong… bike fires and runs on its own fuel now after 10 years of sitting in a garage and a carb cleaning and new kits. But I’m leaking fuel from the area in the picture below. Someone please help me figure out what I screwed up…

 

 

[lmgk77]

BTW my bike is a 2007 RSTD.

 

When I rebuilt my carbs I experienced the same leak, it just poured. As you see its just a slip fit. The material is a firm rubber compound.

After a frustrated do over of assembly R/R of that part I found a very small split on the backside of this "T" fitting,  +/- 1/16", it just poured. I finally replaced it and cured that leak.

 

When  this part was ordered, it took almost 3 months from Yamaha of Japan.

 

Edited February 21 by lmgk77

[tex_waco_usmc]

8 minutes ago, lmgk77 said:

BTW my bike is a 2007 RSTD.

 

When I rebuilt my carbs I experienced the same leak, it just poured. As you see its just a slip fit. The material is a firm rubber compound.

After a frustrated do over of assembly R/R of that part I found a very small split on the backside of this "T" fitting,  +/- 1/16", it just poured. I finally replaced it and cured that leak.

 

When  this part was ordered, it took almost 3 months from Yamaha of Japan.

 

I’m sure that fitting is supposed to be attached to something but when I bought this bike it was not. However, if I’ve followed the carb section of the manual properly that’s a fuel overflow and it shouldn’t be leaking at all from there. But mine is coming out of the actual fitting itself where it’s not connected to anything. I’m thinking I’ve got a float not floating or stuck open, but I could be wrong. 

 

[RDawson]

Look at the needle and seat along with the float itself. 

[tex_waco_usmc]

4 hours ago, RDawson said:

Look at the needle and seat along with the float itself. 

That’s the plan today. I’m going to remove the “T” fitting from between the carbs and run it to figure out which one is pushing fuel and then I’m going to disassemble again and check needle, valve and float. My guess is the float isnt floating as the needle and valve are new but until I open it back up I can’t be for sure. 

[tex_waco_usmc]

On 2/22/2025 at 6:38 AM, RDawson said:

Ok update:

took the carbs on and off 4 or 5 times today. Found the main problem: one of the new needles has what I thought was a spec of metal in the rubber was actually the metal inside it sticking through the rubber causing the needle to not seat properly. Cleaned up one of the old needles and fixed that leak. Re-adjusted the floats again to verify they were right. And corrected to float bowl gasket on one bowl because it was pinched and leaking from there as well. 
 

No, external leaks now! Bike fires up and idles but it’s idling high. I know I still have to sync the carbs; will that help with the high idle? I’ve already checked the idle screw and it’s not currently touching at all. 

[Marcarl]

yep, it might. Make sure you have the idle screw and not the primary sync screw. Idle screw is hard to see, it's hidden, so if you can easily see it, it's not the idle screw, it's hidden between the carbs behind the joiner rail, left side.

[RDawson]

Idle adjustment on a 2nd gen is a thumb wheel under and up against  the tank on the right side. Make sure all 4 carbs are seated well into the intake boots and not sucking air, they can be very stubborn to get seated sometimes. 
Could the throttle cables be tight somewhere and not letting the carbs return to idle?

Edited Thursday at 04:07 PM by RDawson

[tex_waco_usmc]

55 minutes ago, RDawson said:

Idle adjustment on a 2nd gen is a thumb wheel under and up against  the tank on the right side. Make sure all 4 carbs are seated well into the intake boots and not sucking air, they can be very stubborn to get seated sometimes. 
Could the throttle cables be tight somewhere and not letting the carbs return to idle?

Not sure if my last quote went through so I’m redoing it. Throttle cables are good to go. Not tight, I’ve played with them several times to verify. Thumb wheel is backed off of the throttle linkage wheel where it’s supposed to touch. I will check the seating of the carbs again before I go any further and verify I got em set right. And yes they were a pain in the rear to get seated. 

[RDawson]

A trick I use to find air leaks is to spray Walmart carb cleaner around the carbs. If there’s a leak you’ll hear it rev up. Some of the name brands don’t work as well as the cheap stuff for that. 
Are all 4 synch nipples capped? 
Just trying to run thru all the possibilities in my head and my head is a scary place to go.  
 

[tex_waco_usmc]

9 hours ago, RDawson said:

A trick I use to find air leaks is to spray Walmart carb cleaner around the carbs. If there’s a leak you’ll hear it rev up. Some of the name brands don’t work as well as the cheap stuff for that. 
Are all 4 synch nipples capped? 
Just trying to run thru all the possibilities in my head and my head is a scary place to go.  
 

My head is a scary place too! lol Yes they are all plugged I checked them today. One of them the very end of the hose that is on it is cracked so I’m planning on replacing or shortening that hose tomorrow to get to noncracked line. 
 

I reseated all the carbs today. I loosened the bolts/nuts that hold the carbs together to make the carbs move semi-free of each other and reseated each individually. Seems to have helped bring the idle down a bit. I feel like a sync will correct the rest. My sync tool should be here tomorrow to get that done. 

The bike now runs on fuel from its own tank after a thorough cleaning and then another thorough cleaning and then another thorough cleaning after that and a replacement petcock… and of course as one should have expected based on what the petcock looked like the sending unit doesn’t work! 

Oil and filter changed, Front brakes bled through with fresh fluid. Clutch bled with new fluid (it was definitely low on fluid and had no tension on lever when I started that job), lever feels firm but bike stalls when I put it in gear and won’t start with clutch pulled in if bike is in gear so it isn’t right yet. Rear brakes are on the agenda for tomorrow as well.
 

Considering this bike has been sitting since 2015 it has come a long way in the past 2 weeks I’ve owned it. 

Edited Friday at 02:47 AM by tex_waco_usmc

[RDawson]

The good news is once you get em dialed in they are great bikes. Sounds like you’re well on your way to reviving a gem.