[mark]

First, hello to all, this is my first post!

Now, I have a 1989 Yamaha phazer 480. It ran great for the past few years and now this year it's running like crap.

Compression is 110 in one cylinder, 120 in the other. Nice spark from both plugs. Changed gas. Checked both sets of reeds and they look fine! The sled runs but only one cylinder is working. Since one is working I assume the fuel pump is working plus both bowls were full of gas.

Now, I took the carbs out but I really suck when it comes to carbs. Both of the floats work and the needle valves work correctly. Also the main jet (big hole in the middle going to the top part of the carb) are clear. Other than that and the butterfly there are no other parts to the carb to remove and clean? What else do I clean? Also, there is only one screw on the top of each carb so how are these carbs adjusted? Does anyone know what the electric switch on the side of the carbs is for?

Is there any other reason only one cylinder would work other than the carb?

Thanks for any help!
Mark

 

[lhanscom]

Pull the carbs off again, and take a look at the idle circuit. There is a jet that sits in front of the main jet, that's the idle jet. Pop it out and see what it looks like. The wire that hooks onto the side is part of a TORS system. It is a safety setup that kills the ignition if the throttle sticks, and you let off the gas. There is a switch on both carbs, and the throttle. Hope that helps.

 

[mark]

my parts picture shows a pilot jet and a main jet so I'm assuming the idle is from the pilot jet. I will take it out and look at it. It just unscrews, correct? Also, does that cap just pop off or does it screw off. I think this is probably the problem, hopefully. The carbs are still off so I'll check it out tomorrow morning.

One other question, if the pilot jet is clogged will this keep the main jet from working when the throttle is opened?

Thanks alot for the help!
Mark

 

[lhanscom]

If it has a rubber cap on it, then yes it just pops off. The pilot jet will effect the entire range of throttle in a decreasing ratio. So at idle its 100% and at WOT its like 2% responsible for the mixture. What does the plug look like on the cyl that's not firing? Black? Wet? Dry?