Float level twilight zone

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tothemax93

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In the process of tuning my muscle kit. I Want to start out from square one,so the first step was to check and set the floats. Took the carbs apart and set the dry float height as per the sticky in the carb section, shooting for 17mm wet height, then installed the rest of the muscle kit. I put about 40 miles on it. checked the plugs and 2 of them where white as could be, one was slightly lean and one was slightly rich. They were all set the same on the bench. I thought It must have been a screw up somehow, so I pulled the carbs, and reset the heights. Six times later, all four carbs are reading 16-17 MM wet. Each carb is internally a different float height to achieve the 17 mm wet level. http://www.vmaxforum.net/showthread.php?t=1427&page=3post 22, tried to do ragingmans method of measuring down from the jet block to the top of the float,post 22. His measured ruffly 16 mm down to the float. The last one of the carbs I measured was 11 mm down, and that gave me the 17 mm wet level :ummm: I'm checking the wet level as per sticky, with a clear tube and the mark on the side of the carb. Is there something else in the carbs that could be screwing with me, and causing these differences. I'm not even close to the measurements suggested in the stickies. Am I the guy that has "those carbs" I leveled the bike side to side and front and back just to make sure the huge differences weren't caused by that.
 
If your wet levels are right, which they are, you're good to go. The measurements and little casting circles and such are only to get you close, wet level is the final word.

What might be messing with you is the depth of the needle seats in the carb bodies....measure to see if they all protrude into the float chamber the same amount.
 
Interesting but not a clue here! Maybe float needle rubbers are worn?? But I've never seen that in any carbs I've ever torn apart ut ethanol does some crazy shit

Sent from my GT-P5113 using Tapatalk 2
 
are the carbs clean, are rubbers on the carb slides in good condition, is the spark good, how old are the spark plugs, thinking maybe your carbs are dirty
 
I didn't disassemble them completely, but I commonly use seafoam, have recently done the shotgun procedure, rubbers are in good condition, spark plugs are new as of last sunday. When I took off the covers for the floats everything looked clean. the spark seems strong. I put on about 15 miles today, to check out how it ran with the newly adjusted floats. still lean and some soot, but not wet from gas. I have the A/F out 3 1/2 turns right now.I rechecked the wet float levels for my own peace of mind. all 4 were a perfect 17 MM. Going after the jets next. I'm going to run it at around 8000 rpm for a time, kill the motor and see what the plugs tell me.
 
I've seen pics of some with the needle seat pressed in to a different height.

Will that really make a difference if setting the levels by caliper measurement method.

I realize the tab will be bent quite differently for that carb, and you wouldn't want to mix up floats, but isn't the end result of the caliper method to approximate what the wet level is going to be when fuel raises the float to the cut off point?

In essence I don't really see the relevance, but then again I'm no geometry expert....

And has been said the wet level check is the final say...
 
The last set I did, the seat on one carb was quite a bit off from the others. The wet check is the only way to know. Cycle the pump till the bowl is really full and the inlet needles seat. Watch out for air bubbles in the tube that screw you up. I do a wet check on the bench with the rack split in two. Then recheck on a level bike. A sync is a must.
 
as danny said if all good wet then good to go.
are you setting wet on the bench or when carbs on the bike.... if on the bike are you on the centerstamd?? not side stand....
 
as danny said if all good wet then good to go.
are you setting wet on the bench or when carbs on the bike.... if on the bike are you on the centerstamd?? not side stand....

checked the wet levels on the bike, on the center stand. I also put a level on the bike, side to side and front to back, and shimmed accordingly. I'm quite satisfied now with the wet levels. I just struggled with being so far away from the guide line specs for setting the dry float levels, and that the carbs were set at a different dry float heights to reach 17 MM wet.
 
I've seen pics of some with the needle seat pressed in to a different height.

Will that really make a difference if setting the levels by caliper measurement method.

I realize the tab will be bent quite differently for that carb, and you wouldn't want to mix up floats, but isn't the end result of the caliper method to approximate what the wet level is going to be when fuel raises the float to the cut off point?

In essence I don't really see the relevance, but then again I'm no geometry expert....

And has been said the wet level check is the final say...

Good thinking Rusty, you're absolutely correct.....the float will always be in the same position for a 17mm wet level no matter where the seat is....the tab is the compensating factor. :doh:

Yes, air bubbles will screw you up good, I bench test in pairs also, it's easier to work the bubbles out.

Also, you should create at least the same amount of head pressure on the fuel as the fuel pump to insure proper seating....my set-up kind of resembles a large bong.....should the POlice come busting in during a float set I would probly have some s'plainin' to do.

Here's an early version...since been upgraded to a platform with leveling bolts and Dynojet decals (very important!) :biglaugh:

 
checked the wet levels on the bike, on the center stand. I also put a level on the bike, side to side and front to back, and shimmed accordingly. I'm quite satisfied now with the wet levels. I just struggled with being so far away from the guide line specs for setting the dry float levels, and that the carbs were set at a different dry float heights to reach 17 MM wet.

Dry setting to get you close but once you got the wet set you should be golden......
 
Happy 4th Guys
I'm trying to diagnose a problem I’ve been having with my 91. Idle seems fine, 1K constant. trying to get her past 3K in 2nd, and she starts to bog, low power. 3rd even worse.
Here's the strange thing:
I ran 2 leak tests around the carb boots. 1 with starting fluid and the other with propane gas. Engine did not change rpm to indicate an air leakage. So I figured I was ok.
Next, broke down the carbs to clean them twice. 2nd time using an ultra-sonic cleaner.. That removed a ton of shit. Cleaning solution looked like swamp water afterwards. Figured it should run nicely after that.. Wrong.
I synched up the carbs after each removal. All are in synch with each other.
I read on one of these threads. To check to see if your bike is running rich or lean, take her out for a test run, but bring some duct tape with you. Cover 1/2 of the air intake ports on each side of the air box. Do the same run again. See if she runs better or worse. If better, then your bike was running lean (without the tape)... Too much air in the mix.. If it runs worse, it was too rich. (Too much fuel to air) in the mix without the tape.
When I tried this test, my bike did almost a 180 in its performance. Before the test, I could barely get past 2nd gear at 3K. After the test, I got her up to 4th gear around 6K, with smooth transitions between gears.
Sooooooooo. After determining that I must have had excess air getting into the engine someplace, I decided to take off the carbs again to check the Boots.. I found one almost split in half.. Multiple cracks on the others.. I was happier than a pig in slop :),, Found the problem.. So I ordered new ones..
I thought I had finally found the culprit to my dilemma. Considering the bike was running well, then, one day it started this mess. So logically, you would think that something drastic must have happened to cause this affect so suddenly. Like a sudden crack in a 22 year old piece of rubber. Absolutely feasible.
Put the new boots on and took her for a test today.. SAME DAMN THING..
I could actually ride her with the tape in place but it shouldn’t be that way..
Also, my idle circuit seems to be a bit off.. When coming down out of 4th to idle, she sometime dies out.. I've been trying to adjust the A/F screw settings. Right now they’re like 2 3/4 turns out.
I checked my levels last month and they looked OK but I’m not sure of the float heights.
I may have to pull the carbs again to check them, but I’ll do another wet check later today.
It seems that float levels are critical to the operation of the bike, especially around lower rpm ranges. wether your doing 20 or 80, you will be hitting lower RPM ranges when shifting to a higher gear.
So I’m wondering if this is my problem.. I Don’t know..
BUT, I had a question:
Going the book, the wet test should read a level, mid-way between the top and bottom of the diaphragm cover.. The book says “Vacuum chamber”.
Is that correct?
If so, wouldn't the length and inner diameter (I/D) of the tubing used for the test, render different results?
I mean, if I tested one bike, using a 1 foot tube with an inner diameter (I/D) of 1/4 inch, attached to the rubber drain hose, Then test another bike using a 2 foot piece of tube with a 3/4 inch I/D, wouldn’t the level be different, simply because more fuel volume is sitting in the 2 foot piece of tubing, physically leaving less fuel in the bowl for the reading?
Or am I missing something :)
 
What ever the size of the hose, the float bowl will still be the same height internally if its full of gas. you would just need to keep cycling the fuel pump until it stops clicking, to make sure its full.
 
When it stops clicking, the bowls are full. (supposedly).
So, you have a certain volume of fuel sitting in each bowl.
Unless you have an auto feed on the bowls (your key in the run position and the bike on), that volume will not be replaced till the bike is cycled on again.
So, if tube 1 requires 5Ml to fill up to the reading of 1/2 way point of the carb cover, and tube 2 requires 10 Ml to trying to get to the same reading, how can the readings ever be equal between one person and another?
What I'm really asking is, how one person can say it should be 15mm or 17mm if they are not all using the exact same tubing. One person may have 14mm simply because he's using a larger diameter tube for the test. He might be going crazy trying to get to 17mm, pulling his carbs off to re-adjust the floats.
If you purchased the leveling kit that Yamaha recommends, then you can be 100% sure of your readings.
 
I do the wet check with the bikes fuel pump, just use an extension hose, run it with the drains open at first.

Use the drain screw like a bleeder to obtain multiple checks too see if its consistent.
 
"I do the wet check is in the bikes fuel pump, just use an extension hose, run it with the drains open at first. "
Really.. Never thought of doing it that way? Humm..
I just tested the levels of each carb with a R/C Fuel tubing that has the same I/D as the rubber drain hoses. They are all LOW.. About an ½ inch (12.7mm), below center.. So, I now have them inside and will be coming up with a way I can check them wet and dry in the house.. Pulling these babies are not the easiest thing in the world..
AND THAT DAMN RETURN THROTTLE CABLE.. WHAT A PITA.. :damn angry:
1st time I had to put that back in, took almost 1/2 hour.. :bang head:
Now I use my mini ratchet to hold the cable stopper in place while threading the cable though the assembly.
 
When it stops clicking, the bowls are full. (supposedly).
So, you have a certain volume of fuel sitting in each bowl.
Unless you have an auto feed on the bowls (your key in the run position and the bike on), that volume will not be replaced till the bike is cycled on again.
So, if tube 1 requires 5Ml to fill up to the reading of 1/2 way point of the carb cover, and tube 2 requires 10 Ml to trying to get to the same reading, how can the readings ever be equal between one person and another?
What I'm really asking is, how one person can say it should be 15mm or 17mm if they are not all using the exact same tubing. One person may have 14mm simply because he's using a larger diameter tube for the test. He might be going crazy trying to get to 17mm, pulling his carbs off to re-adjust the floats.
If you purchased the leveling kit that Yamaha recommends, then you can be 100% sure of your readings.

No matter what the size of the hose, full is full. If I use a 1/4 hose for one and a 3/8 hose for the one next to it. they will read the same float level if the hose's are full. I would just have to cycle the pump more on the 3/8 hose because it would take a greater volume of gas to fill it. just keep cycling the pump until it doesn't click anymore. then whatever size hose you are using should be full, for an accurate wet level
 
Well that makes sense if you're doing that way.. Hell, you could have a hose the size of a coke can and it will eventually level out with the pump constantly priming the bowl.. :)
 
Well that makes sense if you're doing that way.. Hell, you could have a hose the size of a coke can and it will eventually level out with the pump constantly priming the bowl.. :)
Exactly:eusa_dance:
 

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