Yamaha T9.9XEHB Carb "Starting Rod" questions

[NauticaResearch]

Original Post:

Hi all,

I have a 2014 Yamaha 9.9 and I'm servicing the carb and have it pretty much taken apart for cleaning. In looking closely at the exploded view of the internal parts details found online (attached) I see that the rod (pointing straight up in the center) in one of the pictures Ive attached is the "starter rod" (red arrow?) . If you look even more closely you can see a hole for a screw (yellow arrow?) nearly adjoined to the starter rod/rod hole located at roughly 10:00.

My question is, what is the purpose of this starter rod and the neighboring screw?

Neither seems to lead anywhere fuel or mixture related. On extremely close inspection there are no apparent visible passages/ports for either fuel or air in the associated bowl receiver. In the parts breakdown (attached) the bowl receiver (one of the arrows) is actually called a "plug".

I ask this because when I disassembled the carb, the head of the screw (next to the Starting Rod assembly) was missing. I suspect that its purpose may be to simply hold the starting rod receiver in place. I cant figure it out.

The engine ran reasonably fine when I pulled the carb, but as the engine itself is new (to me) I wanted to clean the carb and check it out before putting the engine into sea service. With this screw snapped off inside the bowl I'm thinking of attempting micro surgery to remove the screw remnants. But if it doesn't do anything useful in this specific T9.9 application maybe I can just ignore it and button it up. I also don't want to buy a new bowl assembly if I cant get the screw remnants out without mangling the threads.

I also wonder if maybe some of these these carb bodies are used in multiple applications and ported (or not ported) depending on the application/vessel/vehicle/etc.

Any insight is appreciated.

Thanks!

KM

[boscoe99]

Well tell us man. Don't keep us in suspense. Inquiring minds need to know.

[99yam40]

maybe accelerator pump
to shoot a little extra gas in for starting enrichment

[walleye1]

????????????

[boscoe99]

The 6DR-14301-10/11-00 carburetor is used on all Yamaha T9.9B models from January 2013 though 2017.

[99yam40]

If my memery is still half A$$, I believe Rod said on some small motor carbs that a plunger would increase bowl pressure for a little bit to increase the amount of fuel delivered thru the jets for accelerating RPM.

I do not remember what motor he was talking about, and
but I could be all wrong

[NauticaResearch]

Disassembled 2014 XEHB 6DR10 Starting Rod Chamber

Thanks to you both! Part of my mistake was assuming that the Starting Rod Chamber "B" wasn't fully machined and ported below the plunger itself. I mistakenly (dumb) thought that the top of the plunger was the base of the chamber because it wasn't easily movable (stuck). I gave it a better CRC bath and it freed up with a little more encouragement. Once I did that I was able to complete the disassembly of the rod chamber components. Now I'll be able to clean the ports below the plunger and blow it out better. Im sure its the same setup on the 2012 I have. I'm still concerned about the broken screw that seems to do little more than hold the brass rod guide in place, but once the bowl is on the main body, the bowl mating surface itself might continue to hold it together as it apparently did for the previous owner.

I've attached some pics which are more useful than my blah blah.

I sure appreciate the help and this useful forum. Thank you all!

Merry Christmas

KM

[panasonic]

Does item#20 and #32 mate to each other when the bowl is on the carb?

If so, the screw was there to keep #20 in place while putting the carb together...after that it serves no purpose, it is sandwiched between the carb body and bowl. But it is hard to tell from the pictures...

If not, then you are going to have to remove that broken screw or devise a way of keeping #20 in place.

[NauticaResearch]

#20 and #32

Yes, they directly line up and are guided by the rod itself when the bowl and body are brought together. Also, #32 has a rubber seal that appears to mate and compress on #20’s surface. What you’re suggesting about assembly makes sense. I’m gonna give it a try and hopefully avoid trying to drill that screw out. The schematic doesn’t really reference any other function for that screw, but I’ve been wrong countless times today. Thanks for the guidance.

[boscoe99]

Does item#20 and #32 mate to each other when the bowl is on the carb?

If so, the screw was there to keep #20 in place while putting the carb together...after that it serves no purpose, it is sandwiched between the carb body and bowl. But it is hard to tell from the pictures...

If not, then you are going to have to remove that broken screw or devise a way of keeping #20 in place.

That is the way that I remember it. The piston is spring loaded. The screw holds it down in place.

Might be time for a new fuel bowl.