Hey,

I took apart the carbs on my 1988 Exciter 570 today, and much to my surprise there was a big phillps head screw where the power jet should be and NOTHING in where the main jet should be. The sled has ran beautifully up until the more recently when it has occasionally bogged out on a hard take off from a stop occasionally.

Could this have anything to do with my bogging problem? And why would someone do this? The sled was an 88, but bought new as a left over in 1991 by a relative. I know for a fact that he did not do any modifications of this sort. Were there some updates sent out in years after for the 88 yamaha? Also, carb heating and TORS have been eliminated.

Thanks
Dan

Ok , I forgot about the Yamaha update to plug off the power jet, but I thought it was supposed to be re-jetted? or was the main jet supposed to be eliminated all together?

Thanks again
Dan

If my memory is correct, They had a fuel foaming issue in the bowls on those motors from harmonics and the only way to get enough fuel was to pull the mains.. again my memory is fuzzy and I am certain of the fuel issue.. just not 100% on what the cure was.

Here is what the manual shows that threw me off:
http://home.comcast.net/~dgohmann/pichost/manual.jpg

The Power jet is removed and plugged as it should be, and quite honestly I'm not sure how the main jet would even be functional down there, I did locate a jet stamped 320 at the bottom of where the needle sits, I'm going to guess thats the main jet, and the one pictured here is storage for an additional jet?

Dan

Ill try to explain that setup...On those carbs there should be a brass nozzle that hangs in the center with an O-ring on it, that seats into the bowl. The jet mounted in the bowl lets the fuel get drawn thru a passage in the bowl casting and up into the carb thru that o ringed nozzle. So yes your man jet is a 320.