to much vacuum on carbs

trying to synic carbs and i hook up my homemade monometer and start my bike. carb 2 and three suck all the fluid out of the monometer. I use marvel mystrey oil. Is their a way to ajust the vacuum. I already tried using the air fuel mixture screws that did not change nothing.

 

gotta adjust carbs to run the run the same speed thus giving the 2 carbs the same vaccum pressure. try seeing which ones pulling more air shut the bike off and adjust then restart the bike till you can get it close to leave running and adjust. that would be my best theory on it.

 

The problem isn't the engine, or the carbs, it's the way you made the manometer. A healthy engine will suck out MMO or ATF from a homemade unit very easily. You need longer tubing, or to switch to a pair of bottles.

 

how long should the lines be or how to build a simple bottle setup.

 

this is my setup. rubber corks 80 cents. hose was like 20cents a foot. bottles were snapple tea for 1.29 a piece. one hose runs to about half inch from the bottom of both bottles. 2 more hoses of equal length go in the cork about quarter of an inch. filled up with colored water to where it wont be sucked back in the hose.

 

Kool thanks, will be building it tomorrow I hope

 

http://www.xjbikes.com/Forums/viewtopic ... art=0.html

 

You need restricters in the tubes, short pieces of the 'straw' that comes with WD40, set those in the lines near the ports.

 

And don't use colored water; you don't want to use anything that would be unfriendly to the motor if some of it does get sucked in.

 

thats why i and i recommend you do too inline to just add enough water. in case it does suck that much it'll never hit the actual tube pulling air ^.^

 

The "BB" devise is easier to build than the "2 bottle"

-and-

Restrictors don't have to be complicated WD-40 straws epoxied into hoses - Just cram some paper towel into the tube rather tight, but not too much.

 

Does anyone have a link to the BB device? I'D like to give it a try...

 

this is the one I have. it works well, but I think I am going to try the bottle method because the added volume of air in the bottles works as a pulse damper and will give a smoother reading.

the bb design has a tube in a complete loop with a bb in it for a reference point and then the two lines that attach to the carbs is actually one tube with a spiral loop attached to the reference loop with stoppers to prevent the bb in it from being sucked out. you hang the loops from the handle bar and gravity does the rest. the carb bb flutters back and forth pretty good so you adjust it to flutter evenly on either side of the reference bb. hope this helps.

CN

 

You need to adjust the sync screws, not the fuel mixture screws. There are 3 + the idle screw that adjust the 4 butterflies relative to each other.

I use and swear by the homemade 4-tube manometer with restrictors, however, the columns need to be 3 feet tall (at least) with another couple of feet to reach the intake nipples.

Still, the engine can suck the fluid out of the tool, but it'll take a second or two longer, and if that is about to happen, do as som1somwhere said and shut off the bike, let the fluid settle, and make coarse adjustment, start the bike and try again. Make sure your idle is reasonable before you even start your syncing.

No matter what, ATF-4 or MMO have about 1/13th the specific gravity of mercury, i.e. one inch of mercury is over one foot of these fluids. So you have to get the intakes within 3 inches of mercury (1.5 psi) to not suck the fluid out.

Two snapple bottles only measure about 1/5 of that pressure difference, but their response rate is slower due passing fluid through a tube much smaller than their measuring columns. I personally don't like the feature, but others swear by it.

 

This is a big part of getting the bike tuned right, why would you rely on a home-made sync tool? We have to do this often enough, that I think it might be best to just invest in a set like this one.

http://www.carbtune.com/

I have a set, and use it on all my tuneups. It has paid for itself 3 times over!

And I know I am getting good, accurate readings. I bet Chacal even sells them!

There are too many variables to worry about, why not make your life a little easier?

Just my opinion, I could be wrong.

 

I'm afraid i'll need a picture or a drawing to understand, I'm kind of visual.

 

um, because it isn't rocket science and is not difficult to get accurate readings with a DIY setup?

CN

 

if I have time later I can draw up something for you. or I will at least snap some pics of the setup I got off ebay.

CN

 

I would appreciate, thanks!

 

http://www.xjbikes.com/Forums/viewtopic ... =next.html

Here's the link - that contains every needed sync- link

The hobbyist will be happy to build inexpensive, but effective tools - -

Cram the YICS passage with oily rags instead of the $35 tool, or spending 2 hours making the home-made version.

Build a FIVE FOOT TALL 2-tube sync tool, if you are NOT inclined to build the 4-tube Manometer. (also 5 ft tall).

Click the link for more info. Tons of ideas in all the threads linked.

 

Thanks for the link, TIMEtoRIDE!

 

Guys, thanks for all the input. Your helping me out a lot. Just bought all the stuff needed to build the bottle setup. Going to the garage to build now. Will keep u guys posted thanks again.

 

remember, pics rock! but videos are even better!

CN

 

I finished building the four bottle setup. I took a pic but file was to big. Will have to take anther one with less resolution.

 

Hey, I've got three XJs and I have a CarbTune too. Great investment, makes it a 10-minute task.

But some folks prefer the challenge, and it can be accomplished with the various DIY methods.

 

A "4-bottle" set-up will NOT work !! re-tool to a 2-bottle - -

pic stolen from someone - - some where . . .


Did you look thru my link??
http://www.xjbikes.com/Forums/viewtopic ... =next.html
*link*

The bottle system is so short, that you are adjusting for FLOW between the bottles, more than LEVEL, as that would take a whole lot of patience and waiting, for the 2 bottles to achieve levelness.

Run a fan . . .

 

I know its been a while built the bottle setup. Was able to synic 1 and 2 carbs but when i try to syinc 3 and 4, four just keeps pulling a crap load of vacuum.

 

Possible air leak at 4?

Gary

 

Just to note, the1/2 sync screw has the opposite effect as the 3/4 sync screw.

 

An air leak will drop vacuum, not increase it.