Mikuni 28.5mm carb

[Ken Anderson]

I'm having trouble with a Mikuni flat side carb (copper choke lever) on a Honda CR80. The motor runs fine at idle but when the throttle quickly opened up all the way the motor boggs and will die if the throttle is not released. Once the throttle is releast it runs fine again until the throttle is opened quickly. In less then a lap the plug is fouled so I know it has to much fuel. I currently have a 30 idle jet and a 180 primary jet in the carb with the float level set just below half a bowl and the needle jet set in the middle. I have tried everything from a 17.5 to 35 idle jet and a 140 to 210 primary jet. Adjusted the float up and down and raised and lowered the needle jet. No matter what I do it has no real effect on the motor. Is there something I'm missing or not doing right?

I'm using a Mikuni rectangular pump with a Honda "T" to simulate gravity feed. I have run a stock Kehin and it seems to work fine on the motor with the exception of fuel pick up problem in tight corners.

Thanks in advance for any input,
Ken A

[Jeff Payne]

quote:

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Originally posted by Ken Anderson:
I'm having trouble with a Mikuni flat side carb (copper choke lever) on a Honda CR80.

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I have bad news, that isn't the same popular Mikuni used on CR80's. The Mikuni that is used is specifically the one from a Suzuki RM80 and it has a pull up choke with a black knob on it. I started out with a copper choke carb and was having similar problems as you describe, a friend asked George Banke what to do to and he said I needed to buy the right one.

Once I did have the right one, it ran fine. I got mine from www.msquaredkarting.com, Bonnier was very helpfull in the jetting and correct plumbing of the fuel lines also.