400f sleeves and bore

[wilber551]

stock jetting, i think there 105's. i have a 24 mile loop that i go on, most of the loop being 55+ but when i get into town the and do alot of start stop the engine acts like it loads up and wont run for about a mile out of town then clears out and runs fine. the ideal screws are 1 1/2 turns out. i havnt been able to test it any further though because yesterday my ignition switch took a shit.

 

[crazypj]

Sounds like float level is 'off'?

 

[wilber551]

you are probobly correct. i bent the float bowl taps a but to lower the level but i only eye balled them. i need to get clear tubing and measure them correctly.

 

[redwillissuperman]

Thanks, I forget stuff.
That bore sounds familiar for some reason?
I've found you need to raise float level by 1.5 to 2mm, drop needle 1 clip (usually move to second from top) then you can fit bigger main jets for top end.
I haven't done a 'big' 400f since about 1988

When you say RAISE, do you mean going from 21mm (stock) to 19mm (more fuel in bowl), or going from 21mm (stock) to 23mm (less fuel in bowl)?

Isn't the stock 75 Main, 40 Slow? Going to a 105 seems very rich, even for a 466.

Stock clip position is a #3. Going to #2 would lessen fuel.

I would think that 80-92's would be ideal with the needle position at #3. Dropping the float level (less fuel) would help the bog from the open element air filter,

Or am I crazy?

 

[wilber551]

You are right. When I said raise I mention lower, sorry! I haven't been able to work on the jetting due to either a bad voltage regulator or the rectifier. Damned 30 year old components Haha. Its annoying when u spend 1500 to get the motor solid then the other stuff starts shitting out. I will get that stuff sorted hopefully by Tuesday. I graveyard so its hard to get stuff done. Thanks for your help though. One question, why would a rebuild cause such a dramatic change in jetting? It ran almost perfect before the teardown

 

[lingo]

increase in the volume of the cylinders changes intake air velocity in the carbs. You have to compensate for the faster velocity of air flow in the carbs by rejetting to correct the air/fuel ratio.

 

[crazypj]

When you say RAISE, do you mean going from 21mm (stock) to 19mm (more fuel in bowl), or going from 21mm (stock) to 23mm (less fuel in bowl)?

Isn't the stock 75 Main, 40 Slow? Going to a 105 seems very rich, even for a 466.

Stock clip position is a #3. Going to #2 would lessen fuel.

I would think that 80-92's would be ideal with the needle position at #3. Dropping the float level (less fuel) would help the bog from the open element air filter,

Or am I crazy?

I found that dropping needle (clip closer to top) plus raising float level (from 21 to 22.5) cleans up mid range and 'cruise' at part throttle
You can use around 98 ~105 main jet without having problems (on 400 F1 & F2)
smaller than a 95 main runs lean with K&N + exhaust

 

[wilber551]

Hey thanks for your help guys I been tweaking on it a little every day.