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Carb Tuning on a 2000 Phazer

4K views 6 replies 4 participants last post by  Tacoman 
#1 ·
I am doing the fine tuning on a set of cleaned and rebuilt carbs on a 2000 Phazer. It's running pretty good. I have a couple of related questions.

1) I am trying to sync the carbs using a set a dial type vacuum gauges for motorcycles. I removed the YEIS chamber and blocked the open ports with a stopper drilled to accept a brass tube. Routed a vacuum line from the brass tube to the vacuum gauges. It is airtight. The problem is that manual calls for a manifold vacuum of 200 mmHg and a difference of 10 mmHg. My question/problem is that at idle it only draws about 90 or 100 mmHg. The needles jump around a lot but settle down when the restrictor valve at the gauge is adjusted almost shut. I can sync them so they draw the same vacuum and it does idle a lot smoother. My question is: Why the low vacuum. The sled runs as well as ever so I am pretty sure there is nothing grossly wrong. Is there something wrong with my test setup?

2) The choke/starter/enrichener cable setting has me confused. The manual says there should be one mm of cable freeplay. The plunger assembly is preloaded with a spring so there really is no freeplay. I set it up so there is 1mm of "freeplay" when the enrichener lever on the dash is full on. This keeps the plunger from "bottoming out" when choke lever is fully on. The plunger is also fully seated when the lever is off. This makes sense and seems to work ok. Is there a better procedure? Am I missing something? The manual is not very clear.

3) How the heck do you replace the in-tank fuel filter. I fished it up to the filler opening but could only get it 1/2 way out. The line was too short by about 2 or 3 inches. Is there a trick or some other way of getting to it? It's not covered in the manual.

Any help is appreciated.
John
 
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#2 ·
Wow its a lot simpler than that!
2000 would have rack carbs!
Start with getting them opening the same, I put a spring clamp on the throttle lever.
Remove the top cover and find the Philips screw going threw the nut.
With the throttle wide open, look into the bore and inspect that both are the same, flush with the top.
Adjustment is done with loosening the screw and turning the nut.
Next would be the chokes and the air screws.
Then I use a drill bit and use it like a feeler gauge to set the idle screws, get both to have just a little drag.
Then fire it up and count the turns to adjust the idle up till it will sustain itself (as low as possible)
Now turn the air screw out till the RPM is as high as possible, turn down the idle to where you want it!
 
#3 ·
I did the bench sync. The Yamaha Service Manual also recommends doing the balance with a gauge while running. I am having a problem understanding why there isn't a more vacuum at the ports. Its only 1/2 of what the manual says is normal. Probably something with the gauge setup is not right.
 
#4 ·
I would venture to guess its your test equipment and not give much more thought to it after you compare the butterflies at wide open. You should see a slight deviation between the two. Report back on that.

As for the plungers, if you loosen those barrel nuts all the way in, the pressure will almost be removed from the springs. Off the top of the barrel nuts is where you want to measure or "feel" for the freeplay. You need to factor in that yours is a two into one cable on the choke and freeplay at the lever is not where you need to measure. The spec is misleading and it may take an adjustment or six till its right. If either of the cables have stretched or the connector between the three is sticking, your fighting a simple adjustment.

Most likely your the line to the tank filter has become too stiff to fish out. Your in a very gray area here as to the need to change that vs causing more problems. Real piss poor design on yamahas part on this on. Fish wire, long reach forceps, needle nose vise grips and holding your lips just right(along with a few chosen four letter words)and dont let that line fall. You will have a sudden urge to kick some Japanese engineer where the sun dont shine. Pre 97's were so much more simple. You did take the white sleeve out of the filler neck?

If your carbs are still out, be sure that they are square to each other by placing them on a known flat surface. Not uncommon for the bracketry to create a twist between the two and upset things on fuel delivery.
 
#5 ·
Its actually running pretty good. Just a couple of loose ends I would like to clean up.

If I understand correctly you said measure "off the top of the barrel nuts". The service manual shows the freeplay measurement from bottom of the well of the barrel nut not the top. Is that what you meant by "the spec is misleading". It does make more sense to measure off the top with the choke lever off. Incidentally, this gives me about the same adjustment as my original rigging: One mm of added cable travel with the choke lever full on. I am going to take another look at it and make sure it is rigged so the plunger is fully seated with the choke lever off and is not binding when it fully open. I think that may be what they are trying to get you to do.

So the filter is supposed to come out through the filler hole? I thought there might be a trick. Its not too hard to fish it out and get it 1/2 out of the hole. At that point the fuel line is tight. I can't believe it was designed with a line 3 or 4" too short. I did pull the white liner out. That helps a lot. I am going to wait until spring and then get more aggressive. Working outside at 5degF makes the job twice as hard. Besides I want to ride.

I did check for square when the carbs were off. Also, I think I will try a different vacuum gauge to verify the numbers. That original setup should have worked.

Thanks for the help
John
 
#7 ·
That could be it. The measured vacuum is at the very low range of the gauges range and it might not be very accurate. I have another gauge, but it's just a single gauge, that has a wider range. I will try that. I can rig it with a couple of valves and a T, so I can measure left, right, both or neither.
 
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