Replace carburetor on 2005 Yamaha 9.9 4-stroke

[raptorman]

I need to replace the carb on my 2005 Yamaha 9.9 4-stroke. The original engine was manual start, long shaft, regular thrust. I modified to electric start (requiring different flywheel and stator) and replaced the foot with an extra long, high thrust foot. The question is which carb should I buy? Is the fixed air/fuel mixture needle valve different for the high thrust than non high thrust? The part numbers for the different carb choices does not specify. The yamaha part numbers for carb bodies for the high thrust vs. normal thrust are the same, however the part numbers for the complete carbs are different. Which should I choose?

The part number for the F9.9MLHD engine is 6G9-14301-22-00 and for the T9.9EXHD it is 6G8-14301-22-00. The individual part numbers for each carb are identical. I would like to know how the 2 carbs differ. I would think the Body float chambers would be different using different needle valves, but the part numbers are the same (6G8-14381-02-00). Can anyone explain the difference? Much thanks.

[cleddau1]

Changing the carb is probably not necessary, the high thrust leg has a higher ratio gearbox with a different prop thus enabling the engine to run at optimum revs with a slower turning bigger prop. Make sure you have the right prop. What sort of boat?

[raptorman]

I need to replace because the original carb is not repairable. The engine is a kicker for a Starwind 223 sloop. It uses a huge prop at slower speed. That is why I think the carb requirement may be different for the high thrust. Possibly a different fuel/air ratio for the different torque of the lower unit.

[boscoe99]

Look at the carburetor part number for the regular model and then compare it to the part number for the high thrust model. I think you will find they are one and the same.

From a carburetor standpoint it does not know or care what type of lower unit is installed. All the carburetor knows to do is to provide a specific amount of fuel for a given airflow through the carburetor.

[cleddau1]

Boscoe & I are singing from the same hymn sheet.
The high thrust extra long 9.9 is ideal for your application.
Are we misunderstanding that there is some other problem with the carb? As Boscoe says the power head will deliver the same power to the gearbox shaft irrespective of what is below. The purpose of the high ratio gearbox and big prop is so that the engine speed can be in the optimum range for your cruising speed and provide plenty of bite in reverse, nothing to do with the carb.
Try it and see.

[cleddau1]

carb spelling differences

Carburetor (American and Canadian spelling), carburator, carburettor, or carburetter (Commonwealth spelling). It is sometimes colloquially shortened to carb in North America or carby in Australia.To carburate or carburet (and thus carburation or carburetion, respectively).
Normally spelled carburettor or carburetter in UK and pronounced with the emphasis on the third syllable.
https://en.wikipedia.org/wiki/Carburetor

[raptorman]

The carb needs replacement because part of the casting on the main housing was broken while removing the float pin. Since I am replacing, I want to select the proper carb for the application. My thoughts are that the part number for the carb for the high thrust is different than the non-high thrust. If they are identical carbs, why the different part number? The carb to be replaced does not display a part number.

[boscoe99]

2005 F9.9ELRD Yamaha Outboard CARBURETOR Diagram and Parts

2005 T9.9ELRD Yamaha Outboard CARBURETOR Diagram and Parts

Hmmm. I stand corrected. In this case they are different part numbers. My apologies.

Just buy the carburetor that Yamaha specifies for your specific model.

[cleddau1]

Hard luck on the float pin.....
What is the exact model you have?
Around 2005/6 Yamaha changed the 9.9 4-stroke from a 323cc engine to a smaller lighter 212cc engine. This may be causing confusion.
The original ones had an automatic choke.

You will likely need to replace with the same carb that was broken, to fit the engine specs. All you need really is the carb body part that was broken and use all the other parts or just get a used one.

As previously stated the high thrust should not alter the carb requirements otherwise we would have to change carbs every time we shifted gears in our car.....

If you post the model specs you will get more responses. We have an excellent Yamaha mechanic locally and I am picking up some parts on Friday and will ask him.

[raptorman]

The model was No. was F9.9MLHD. I modified it to a T9.9EXHD. My thoughts on different carb attributes are based on experience with an older high thrust 9.9 (basically the same engine) in that with the larger prop and change in gearing, I could run at slightly above idle to half throttle effectively. Rarely wide open throttle. Very economical that way, and WOT didn't increase hull speed much if any. I was able to cruise about 80 river miles on a 6 gal tank.

Really appreciate the combined inputs of responses.

[raptorman]

Will appreciate your checking with your expert. Don't want to drop $400.00 without knowing for sure which model will be best. Thank you.

[boscoe99]

The model was No. was F9.9MLHD. I modified it to a T9.9EXHD. My thoughts on different carb attributes are based on experience with an older high thrust 9.9 (basically the same engine) in that with the larger prop and change in gearing, I could run at slightly above idle to half throttle effectively. Rarely wide open throttle. Very economical that way, and WOT didn't increase hull speed much if any. I was able to cruise about 80 river miles on a 6 gal tank.

Really appreciate the combined inputs of responses.

If you converted an F9.9MLHD to a T9.9EXHD then you would have installed a 6G8 carburetor as part of the conversation. Would it not make sense to buy another 6G8 carburetor to replace the 6G8 carby that is damaged?

[raptorman]

I did not replace the carburetor. When I do, I want to be sure I choose the correct one. That is the purpose of my queries. I can't identify the difference between the two.

[cleddau1]

The plot thickens.........
I cannot see a part number on boatsnet for the carb main housing; maybe this is what is different. I assume this is the broken part.
As this is the part that connects to the manifold it will have to be the same as the original.
You will have plenty of reserve power for your sailboat anyway. I had the same engine on my 32 ft Iroquois for 10 years and upgraded couple of years ago to the lighter 212 cc 9.9 which is not such a good engine.
Will post tomorrow after asking Andy

[cleddau1]

mmm...
intake manifold "funnel" same part numbers also, so much for that idea......
The Starwind looks a nice boat, never seen one in the UK.
Your max theoretical hull speed will be 4.8 kn or a bit more when heeled over sailing.
So assume you will want to be motoring at 4 to 4.5 kn using half-throttle with plenty of reserve if punching into the wind?
I think these carbs are the same and they are using different part numbers to charge an extra $5 but will let you know the Oracle's opinion tomorrow......