Carbs synched but something's off

[BillyRok]

Hey TC - Yes I did remove the emulsion tubes and pilot screws before soaking the carbs, replaced the little o-rings, too. Bike has fresh oil and filter.

Brent - thanks, I'll check the connections you mentioned...special tool required for the cable or just squash the crimp tighter with big pliers?

Sounds like I did the float height measurement correctly, thanks to those who verified. I will check the fuel level with some clear tubing (have already shimmed front tire and center stand to insure carb bank is level), no sense yanking the carbs if they are right Then new plugs and put some miles on it to check coloring, temps in the 60's later this week...finally!

[motoman]

Why would he be checking levels with the engine running Brant. It's done static.

That's the manuals explained procedure 81/XJ for checking fuel levels. Done while idling at operating temperature. Should be 3mm down from base of carb body as manual states. Also warns of spilling fuel on hot things.

I would imagine the early carbs fuel levels would fall in that same level catagory if one wanted to modify the bowl drains to hose them while running looking for any varience between carbs.

[crazy steve]

I've always wondered why the factory changed the float level procedure in '81... Did they find that the 'new' plastic floats weren't as consistent in how they 'floated', or was it just something to baffle the DIYers into coming back to the dealer? Or a combination of both?

[BA80]

That's the manuals explained procedure 81/XJ for checking fuel levels. Done while idling at operating temperature. Should be 3mm down from base of carb body as manual states. Also warns of spilling fuel on hot things.

I would imagine the early carbs fuel levels would fall in that same level catagory if one wanted to modify the bowl drains to hose them while running looking for any varience between carbs.

I'll have to look that up when I get home. I don't remember the engine running part.

That would be a real PITA on an XJ pulling those carbs to readjust over and over. I think I would just do it on the bench and leave it at that. I don't see where idling would make a difference anyway.

[trbig]

The pilots had no holes in them so I asked everybody about that, this was the response...
Quote:
That's Yamaha for ya! Yep, the XJ's pilots are no holed design, they changed the carbs a bit so the pilot circuit gets it's aeration separately, not directly thru the pilot jet, therefore no holes. Enjoy!

No idea who said this, but this may be your problem. The 47.5 stock pilots do indeed have the holes in them. I've heard of many getting replacement jets that didn't have them and don't know the problems they experienced, but yes, you will need the pilot jets with holes in them.

And yes, you do float height with the gasket off. Every gasket will be different thicknesses whether they've been replaced over the years and/or how many times they've been crushed by the bowls, or how hard you tighten the screws,... or replaced with new. It would make absolutely zero sense to measure off of something that's going to have the thickness vary on every set of carbs. Gasket surface is the surface the gasket sits on.

Lots of people seeming to want to help and sometimes you can get some bad info.. Unlike Greg, I've had excellent results from the Carbtune.

And yes, the XJ carbs are such a PITA to get on and off with a stock airbox in place (That doesn't move back like the XS will when you loosen it) that I will never use anything but good pod filters again. The XS will keep the airbox.. no XJ I own ever will. About 30 seconds each way to take the carbs on and off.

Good luck.

[BillyRok]

Here is the picture from the manual showing proper fuel level

[IMG][/IMG]

This clearly shows the correct fuel height being level with the middle of the bowl screw, supposedly 3mm "below from the carburetor mixing chamber body edge." Yet the parallel line representing the mixing chamber body edge (1) looks to me to actually be the lower part of the lip of the bowl where the 4 screws go through into the carb body and not the mixing chamber body edge. Am I being stupid or anal here (you can say it if I am)?
I did check the level of #1 today and it was about even with the middle of the s/s bowl hex caps I'm using. Is it normal for the line to have some air in the bottom of the loop? Opening the drain screw and gravity filling the line leaves a big air bubble at the bottom of it. With all the talk of how critical proper fuel levels are, I want to make certain it's done properly. Thanks for all the help so far.

[mack]

that photo is identical

To sh/lh manual but the narrative is different. Do your carbs have two or three holes in the bell?

[cajun31]

beating this horse to death

Billy,

I seriously think you may be putting too much into this. Just set the float height from the gasket surface with the carbs inverted so that they are all set the same and you will be good. I would not worry myself to death over trying to do that live fuel etc... It really is not going to make that big a difference.

[BA80]

Billy,

I seriously think you may be putting too much into this. Just set the float height from the gasket surface with the carbs inverted so that they are all set the same and you will be good. I would not worry myself to death over trying to do that live fuel etc... It really is not going to make that big a difference.

Most definitely.

[Brent]

[QUOTE=BillyRok;436693]Hey TC - Yes I did remove the emulsion tubes and pilot screws before soaking the carbs, replaced the little o-rings, too. Bike has fresh oil and filter.

Brent - thanks, I'll check the connections you mentioned...special tool required for the cable or just squash the crimp tighter with big pliers?

Tighter? No staying together is usually not the problem, but it might help a little for a while.

Wire must be clean & SHINEY where it makes connection. Dirty, corroded, even just tarnished makes for partial, poor, weak, inadequate or no connection. Intermittent in nature, it varries with voltage, RPM, temperature, vibration, humidity... Such a poor connection can drive you crazy.

good connections; Clean & Shiney.
Any metal to metal contact that conducts electricity. (use sandpaper, pocket knife, wire brush, file; what ever works.
A crimper of the correct size would work well, especially with solder, but I do not have one. I replaced the large wire with one from autoparts. The smaller red wire was poor connection where it joined crimp. I just cut it off, attatched eye end to it and fastened it back onto the solenoid bolt with the new large red wire. Finding the missing smoke is the hard part. after you find it, You will fix/figure something that works.

[trbig]

Billy,

I seriously think you may be putting too much into this. Just set the float height from the gasket surface with the carbs inverted so that they are all set the same and you will be good. I would not worry myself to death over trying to do that live fuel etc... It really is not going to make that big a difference.

+2.. or 3.. or something.