CB360 Tuning

[motormayhem]

I'm finally getting somewhat fed up with the way my carbs are tuned on the 360. I know they wont be great without the stock air boxes but I'm sure I can get it to sputter significantly less at low throttle. It bucks and sputters pretty hard just off idle to about 1/8 throttle. I have a 110 main jet and had the float set to 18mm and that was where it was bucking and sputtering. I moved to a 108 and it was a hair lean on the top end. Moved back to a 110 and ran a float height of 21mm and it was better overall but still bucked some under light load. Moved to 24mm float height (pretty high I know) and it was great everywhere and surprisingly didn't stall after a hard pull or stop, but running at 6K or more for more than about 30 seconds it will run it out of gas. If I let off for a few seconds it will pull hard again until the fuel bowls run too low. So I'm debating would it be better to try to run a 108 main with a 21mm height or somehow modify the float seat to flow more with less float movement so the level in the bowl remains more constant where it runs happy before running out of fuel. Am I correct in my research that the only thing I can change in the carb is the main jet size and not the other jets? Thanks for the input!

 

[barnett468]

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running out of gas in the bowl is very odd . . i would pull the fuel line off the carb and open the tank valve and drain some gas into a glass . . if it drains slowly, you likely have a prob with the valve in the tank.

if the gas flows freely then you can try to see exactly where the needle tip seats on the brass seat . . if it seats no more than 1/2 way up the needle, you can increase the size of the seat by 1 number drill size if it seats right around 1/2 way . . if it seats closer to the tip, you can go up two number drill sizes.

 

[motormayhem]

Thanks for the suggestion. I'm pretty sure what is happening is the draw from the engine is making the fuel level too low in the fuel bowl as the float needs to drop lower to open the needle more to flow more. It has strong flow from the petcock on both outlets.

 

[barnett468]

Thanks for the suggestion. I'm pretty sure what is happening is the draw from the engine is making the fuel level too low in the fuel bowl as the float needs to drop lower to open the needle more to flow more. It has strong flow from the petcock on both outlets.

sure, no prob.

this will never ever happen on a stock or semi stock engine so either you have 200 hp or something is wrong.