Yamaha Phazer II carburetors - Snowmobile Forum: Your #1 Snowmobile Forum
View Poll Results: How do I tune a Phazer Carburetor
Sould the pilot jet hole be covered with a rubber plug? 2 50.00%
What is the purpose of different sized needle jets? 2 50.00%
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post #1 of 9 (permalink) Old 01-15-2008, 11:48 AM Thread Starter
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Yamaha Phazer II carburetors

I have two old Phazers; I've been tinkering with them for 15 years. Phazers have butterfly Mikuni carburetor units; (they are fastened together)I'm trying to tune them for performance with an Aaen, SLP, and (makeunknown) pipes and not having much success. I have three different carburetor units that I can test out my sleds with. I can swap the units from sled to sled and get the same results in performance. All jets have been cleaned thoroughly and the carbs sprayed out with carb cleaner.

I ride at about 8000 feet and one of the carb units currently has #56 pilots, #145 mains, and #3 needle jets. It blubbers, and keeps blubbering with very poor power soon after the initial surge of power from the pilot jet.
The next carb unit with #56 pilots, #140 mains, and #2 needle jets starts strong and then dies until the choke is pulled. At that point, with the choke out, it performs quite well as long as I'm full throttle.

The third carb unit is still jetted for stock pipes with a #50 pilot, #131.5 main, and a #2 needle jet. (There is no needle in a butterfly carburetor.) This carb has to be choked to get the initial surge and then as it accelerates it requires quick pulls on the choke to keep going.

I disassembled the fuel pump and checked the diaphram and all three carb units start the sleds first crank. Can anyone out there give me some advice on what to do?
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post #2 of 9 (permalink) Old 01-15-2008, 11:58 AM
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post #3 of 9 (permalink) Old 03-29-2009, 03:09 AM
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I was told that the stock jet's are 143.8. My machine that I purchased (95 Phazer) came with 137.5 changed from the previous owner. I want to run a aaen pipe and was told to go with a 145 or 148 jet to be safe run at lower elevation. 143.8 would run good with pipe at elevation it about 4000 ft up mountain top around here.
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post #4 of 9 (permalink) Old 03-30-2009, 07:25 PM
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I'm trying to figure out what you mean by needle jets. Do you mean the main nozzle? There are 2A and 3A nozzles with 2A giving a richer shot of fuel off idle when you hit the throttle. Also stock pilot jet for the mikuni butterfly in the Phazer is #95. I never heard of a #56 or #50 pilot jet for a Phazer but that doesn't mean they don't exist. I would start with 136.3 main jets and go with #95 pilot jets as well as the 3A main nozzle for operation at 8000 feet. One thing to check is that the rubber plugs are in the proper place inside the float bowl chamber. One should be over the pilot jet and the other over the center hole. The third hole does not have one on it. It's also a good idea to change the primary nozzles to the ones with the thru hole (part no. 80L 14489-00-00) if you are going to run aftermarket pipes. Also check out this conversation on Snowest.

What am I missing? 93 Phazer help - SnoWest Forum
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post #5 of 9 (permalink) Old 04-01-2009, 08:26 PM
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Yes, I am talking about the main jet size in there I put a 148. I ride below 3000 ft most of the time the odd times I will climb and ride up there around 3000 - 4000 ft. I ran good the first few times I went out up top with the main jet set at 137.5. down low the sled ran like crap which I expected. I think the carbs are out of sync. I adjusted the air fuel mixture screws to 2 turn out as recommened by the Aaen tech support and installed 147.5 main jets as I have been told that these pipes like to run a little richer than the P.S.I and other aftermarket pipes.
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post #6 of 9 (permalink) Old 04-23-2009, 12:33 PM Thread Starter
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Electrical Problems?

I'm giving up on finding a problem with the carburetors or clutches; I've swapped them back and forth between several different sleds. Regardless of how good the carbs or clutches run on my other sleds, invariably this problem sled will perform the same; it will come off the line great, immediatly run to about 6800 rpm's, but within 2 seconds it will bog back to 6500 rpm's and absolutely will not climb any higher! I've tried heavy springs, enclosed and open Comet clutches, and numerous different jet combinations and settings.
It must be something electrical; does anyone out there recognize the problem? Can you give me some advice on what to do?

Last edited by Tom Angell; 04-23-2009 at 12:39 PM. Reason: left out a sentence
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post #7 of 9 (permalink) Old 04-25-2009, 11:32 PM
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Do you know if your machine has a elevation kit in it? That could be a cause of some power loss just a suggestion.
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post #8 of 9 (permalink) Old 06-14-2009, 10:17 PM
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Had a similar problem was not the carb was cdi pack
switch your cdi pack from the good machine and retry
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post #9 of 9 (permalink) Old 01-10-2011, 10:15 AM Thread Starter
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Phazer I and Phazer II carbs are slightly different

"The Phazer I carbs are slightly different than the Phazer II's & because of a tiny hole in the tube that contains the pilot jet, the rubber plugs are inserted in the pilot tube and the center tube in the original Phazers." With the Phazer IIs you should plug the other two tubes and leave the pilot tube open!
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