Dear Ralph: I absolutely love my Yamaha RX-1, but there is one thing that happens when running it through the rough that concerns me....

Dear Ralph:
I absolutely love my Yamaha RX-1, but there is one thing that happens when running it through the rough that concerns me. Every now and then it’ll hesitate, not quite miss, but you know there’s something not quite right. Have you any ideas on what, if anything, I should be looking for?
Call me the “Happy 4-stroker from Indiana”

Dude, you are such an animal! Anytime somebody starts talking about hesitations when running through the rough, one starts to think fuel starvation and due to the agitation of the fuel in the float bowls. Consistent fuel delivery from a carbed engine is dependent on a uniform level of fuel and consistent pressure in the chamber. What happens is the fuel sloshes around in the float bowl, and in extreme situations the jets can actually begin to suck some air when the fuel isn’t right there, due to the agitation.
This is why main jets are positioned as far down into the bottom of the float bowl as possible, to best avoid cavitation. One thing we’ve found to help in this regard is to install longer main jets. All they do is draw their fuel from a lower point in the float bowl. This not only works well in extremely rough conditions, but on steep slopes where the climbing angle can cause a similar situation. You can get longer mains for the RX-1 CV carbs from Thunder Products (320-597-2700) in jet sizes all the way from 127.5 through 165 in 2.5 increments.

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