Briggs Vanny 23 hp trouble

[chazdo2]

My 23 hp Van Guard keeps running real rich and getting gas in the crank case about every couple weeks. It does this with the stock carb as well as a 38 inch Mikuni I am trying now. I read somewhere that there are differences in the float needle valve with gravity feed or fuel pump feed. Still my dilemma is why is this happening with both carbs? The engine came with a fuel pump and this carb float is working fine?

[slonomo]

Originally Posted by chazdo2

My 23 hp Van Guard keeps running real rich and getting gas in the crank case about every couple weeks. It does this with the stock carb as well as a 38 inch Mikuni I am trying now. I read somewhere that there are differences in the float needle valve with gravity feed or fuel pump feed. Still my dilemma is why is this happening with both carbs? The engine came with a fuel pump and this carb float is working fine?

This thread should be moved to the Big Block section instead of Clone section.

I seem to have experience in this lately lol. Few questions....

1.) Are the carbs you're using new?

2.) Stock Briggs fuel pump?

3.) Did you check the float level in each carb?

[BIKERMIKEYBLACK]

I know on an 18 hp vanguard there is a difference in carb needles aluminum is gravity fed and brass for pumper (heavier weight) the 23 could be the same not sure

[chazdo2]

Its the stock briggs fuel pump. I am using single carb 38mm mikuni. Ill get the jet numbers back hopefully tomorrow. Do you guys have a boiler plate carb size jet size etc for the stock 23hp vanny?

[raydhd]

On my cammed up and ported 1000 cc ironhead with a 38 VM I have a 330 main jet and 40 pilot jet. I suspect your main jet would need to be in the 260 range.

[chazdo2]

thank you

[slonomo]

Originally Posted by raydhd

On my cammed up and ported 1000 cc ironhead with a 38 VM I have a 330 main jet and 40 pilot jet. I suspect your main jet would need to be in the 260 range.

On the 34mm VM Mikuni my main jet is 180, pilot is 30 but it needs to be larger so I ordered a few sizes. I'm guessing 35 or 37.5 will be good.

One thing, the Vanguards don't like a lot of jetting. Ask me how I know lol. They like to run more on the lean side. But, if you are going through all the proper steps to jetting that carb, you'll be fine.

[raydhd]

The pilot jet is fairly easy to determine the proper size. If you need more than 2 turns for a proper idle it is too small. If you need less than 1 turn it is too big. I have a 37.5 on my ironhead. A Big issue on the VM carbs is float height. If that is off you will that no matter what jet you run, tuning is very inconsistent and frustrating. With the crankcase flooding you describe your float height may be too high. If your carb is mounted north/south the height is VERY different than if is your carb is mounted east/west. How do I know this. Some hours of carb tuning on my ironhead. BUT when you get it right it is all worth it. I was very lucky on my 440 cc suzuki swap into the HD cart. Took the needle 1 step leaner and it ran perfect.

[raydhd]

ONE other note. When you get down to the final tuning you may fine that one needle setting is too rich and one step less is too lean. Mikuni sells half step washers just for this issue. Again how do I know ? I absolutely needed a half step washer to get my ironhead Just Right.

[slonomo]

Originally Posted by raydhd

The pilot jet is fairly easy to determine the proper size. If you need more than 2 turns for a proper idle it is too small. If you need less than 1 turn it is too big.

Ray, is your pilot jet on the engine side of the carb?

You must be talking about a "pilot fuel jet", this would be the one that adjusts more or less fuel with the adjustments. This screw will be on the engine side of the carb, or the "fuel side".

Some carbs, like mine, have a "pilot air screw" that adjust more or less "air" at idle. This screw is on the intake side of the carb, or the "air side". If you turn the air screw in all the way, you are cutting off all the air through the pilot jet, making the mix richer. So if need more that 2 turns it is too big, opposite of a "fuel" jet. See pic with red ink.

Basically there are 2 different procedures for tuning the pilot jet on a Mikuni depending upon where your pilot jet is located. The two procedures are opposite each other. It's a little confusing, but here is a good video that explains it very well.

https://www.youtube.com/watch?v=67Nb3DI-B3s