putting my carbs back on. need help

hey everyone, I was putting my carbs back on my bike today after a long wait due to my final exams and I've forgotten where a couple things go and was hoping you guys can help me out.

First thing is I no longer have any idea where all these tubes that come out of the carbs go. I know two hook into the fuel petcock and thats about it

The second is this gold screw that I have. It came from a bag with other bits that I set aside when removing them from my bike so I am pretty sure its not from inside. ( I really hope I am right on this because it was a pain to take them out and put them back in).

Any help is appreciated!

 

Which XJ is it that you have?

 

XJ700.

Gary H.

 

yes, I have an xj700

 

I was about to post a very similar question.
Just had the carbs off my XJ900RL (1984)
They look just about the same as these.



When I was installing them I came the same question. The 2 tubes (marked in blue) are a bit of a mystery to me.
On my machine the fuel hose joins the carb rack between 1 and 2 (looking from seated position over the bike). Yours seems to be between 3 and 4

For now I have just laid them over the airbox until I can figure out what they are, and what they should connect to, if anything.

About your screw, it looks like a mounting screw. After you ride the bike you may discover what is still loose and that will probably be where the screw goes.
Just tuck it away in your jewelery box for now.

 

Have a look at the carb end of the tubes. One will be higher than the other. The higher one is a vent; the lower one is hooked to the fuel transfer tubes, and gets attached to the petcock. Depending on which year/model the other will either just hang free, or hook to a vent outlet on the fuel tank.

The smaller hoses pictured in tis thread are for the float bowl vents (not on every model) and they just hang free.
http://www.xjbikes.com/forums/threads/xj900-carbs.27090/#post-229999

 

Hey k,
Thanks for that.
This has answered my question.

This is what my carbs looked like as I was working on then. The red tubes are the vents then and the yellow is the fuel line.
note: the carbs are up side down.


BTW
If these tubes are removed all together, is there any danger or disadvantage?

 

The red arrows point to overflow tubes. The yellow arrow points to your fuel line from the petcock.

Don't remove the tubes..... They are there for a reason.

 

They are not vents, they are overflow tubes. Imagine for a moment that your carbs overflow while you are riding. These hoses, if routed properly will direct that excess fuel behind and below your engine and onto the road. Without the hoses the fuel will dump directly onto the back of your engine and, with time will drip down onto your exhaust. Your hot exhaust. This would be a bad thing.
Keep the hoses.

For reference, are you certain you do not have California spec bike? I ask because then you would have an additional hose for venting through a charcoal canister behind the right side cover. There would be an additional brass nipple on the top of your #2 carb for this. I cannot tell from your picture if this is the case. There would ALSO be an additional vent line from the bottom of the fuel tank to the charcoal canister. You can read the VIN code and determine if you have a Cali bike, though I cannot recall exactly what the identifier is.

 

If it is a Cali bike, the vapor can is missing (fits into that right side plastic "pocket" behind the plastic side cover)...............

These model ID codes are positions 4-5-6 of the full VIN:

1985 XJ700 Maxim USA: 1FG (49-state version)
1985 XJ700 Maxim USA: 1JJ (California version)
1985 XJ700 Maxim Canada: 1FH

1985 XJ700 Maxim-X USA : 1AA (49-state version)
1985 XJ700 Maxim-X USA: 1FJ (California version)


1986 XJ700 Maxim USA: 1NH (49-state version)
1986 XJ700 Maxim USA: 1NK (California version)
1986 XJ700 Maxim Canada: 1NJ

1986 XJ700 Maxim X USA: 1NW (49-state version)
1986 XJ700 Maxim X USA: 1LT (California version)

 

Thanks for all the responses, I am gonna try to position the overflow tubes properly now now that I know what theyre for.

 

Do these overflow tubes need to be angled downwards?

When I installed the carbs I noticed that the overflow tube that is between 1&2 is difficult to route in such a way because of the fuel line which must go upwards.

In general these overflow tubes also seem to be too short to be routed to a safe overflow location.

Damn wish I paid more attention to them as I was dismantling the carbs.

 

Mine route down on the brake side and rear of the engine. There is actually a wire bracket of sorts that hold them. I have an 85 xj700n.

 

I have a couple questions from this picture.

#1 Above the hoses you pointed to, there are three valves between the carbs, I have hoses the come from these valves. Does anyone know if they are just additional overflow tubes? I am assuming they are

#2 That knob in the middle of the rack, what does it do?


I actually put my carbs back on the otehr night and finally started up the bike after a few months. It started but I think because the sparkplugs I had before were very old it wasn't burning the fuel properly and fuel started coming out of my exhaust
Gonna try new sparkplugs and see if it solves the problem and if not I'll be coming back here with more questions

Edit: One more question, is it possible to flush the carbs of fuel without pulling them?

 

It would not have started if the spark plugs didn't have a strong enough spark. Fuel out the exhaust is the result of a stuck open fuel valve allowing fuel to overflow into the cylinder (remove the oil filler cap and take a whiff). Don't start your bike until you fix the stuck valve issue and change the oil.
Edit: One more question, is it possible to flush the carbs of fuel without pulling them?
No.

Gary H.

 

I don't know

It adjusts the idle speed of all 4 carbs, assuming that all are synced properly.

Not sure I understand, you CAN open the drain screw on the float bowl, drain the fuel and run new fuel through them.
Not sure you would want to 'flush' anything other than fuel and a touch of sea foam if there are new rubber components installed in your rack.

 

Dunno about your bike but on mine, it would be challenging to drain all 4 carbs without pulling off some other components first. I know #1 and 4 easy, 2 and 3 not so easy.



To the best of my understanding:
- the red arrows show where the screw to release the fuel in the bowls is (note the blue orientation arrows)
- yellow arrows show where the fuel will come gushing out. Probably an idea to get a piece of tubing to drain the fuel somewhere sane first. Cold bike = good idea.
- green arrow = idle screw.

 

The carb drains are easily accessible with the carbs in place.

 

I'm thinking he's referring to varnished fuel. Apparently I'm wrong.

Gary H.

 

The red is the bowl drain screw, the yellow is the port where the fuel will come out. Have you wet set your carbs? To do so you will need a pressed nipple to connect a clear tube and check each bowl's level. If you skip this step any cleaning of the carbs may be pointless which brings me to the next question, have you checked your valves?

 

I can only speak for myself, but getting anywhere in with my hands any further than the outside sides of carb 1 and 4 is a contortion challenge for me. Let alone with any of my meager selection of tools.

Damn big hands. But then again urban legend says this an indicator of other assets. But can´t say for sure since I don´t make a habit of comparing my assets! hehehehe

 

You don't put your hands in there; you use a screwdriver.

 

Or an Allen wrench if you upgraded to the fancy SHCS style drain screw.

Admittedly you may fiddle frack around getting a tube on those inner carbs for draining them.
I have tubing what I believe is from a fish tank aerator, it is just the right stiffness and just the right size where I can guide it towards the nipple, center it , push and pop! She's on.

 

Not when you tool kit looks frighteningly similar to this famous set....

 

Whew..... Is it warm in here, or is it just me?

 

My schedule finally cleared up and I can resume work on my bike. To answer your question, I have not checked my valves yet but when i got the bike it didn't have a leaking issue, so I don't know if that would be the cause. I want to do the valve check after I solve this issue if possible. (I feel like if I do too much at once I'll mess it up).

Second issue is I got my bike to start and it's not leaking out the exhaust anymore but I now have fuel coming out of two other places. First is that spot that I circled with the red and the second is the hose that sits between carb 1 and 2. Would these be the result of just too much fuel going to the carbs? Are there common issues that I should be looking in to?

 

Pic 1: I'm not clear on which one is leaking. The top one is the enrichment circuit valve; It may not be completely closing and can allow excess fuel into the carbs. The bottom one is the mixture screw. It meters how much fuel is added to the air passing through the carbs. If not correctly set could also allow excess fuel into the carbs.
Pic 2: Looks like that's the fuel line and should be attached to the petcock.
Is the fuel in the tank low? Why is the petcock switch on reserve?
A large amount of fuel into the cylinders is the the result of stuck open fuel valves in the bowls.
Hope this helps.

Gary H.

 

For pic one, the fuel is coming out of the little copper bit that's in the center of the picture.

I turned the petcock to reserve when I turned the bike off, there's no special reason why I did it and the tank has a healthy amount of fuel in it.

I think the first thing I will do is see if the fuel valves are stuck open. Thanks for the suggestions!

 

I don't mean to scare you but multiple gas leaks means that rubber, seals and other parts are failing in your carbs. If you don't want to take them off the bike due to future leaks you might be better off doing a full job and replace all seals and rubber parts involved.

 

It's the first time I hear about fuel level so hig it lfows by the fuel enrichment plunger ! I didn't even think it was possible.

 

Pic 1 - it's a brass plunger, not copper... BUT if you have gas coming out there, it's leaking and needs to to be pulled and serviced.

Your enricher screw won't leak unless the o-ring is bad

Pic 2 - the tube shown is your fuel supply tube, it should be connected to the petcock--- which.....

Doesn't need to be set at reserve when it's not running. Reserve is only a setting that you go to if you've 'run out of gas' on RUN, and haven't refilled yet... But you'd better, quick. Once you "run out of gas" on Reserve, you are really out of gas.
Run, and Reserve, are both on vacuum operated side of the petcock. Neither will allow fuel to flow when the engine is not running, when the petcock is in good shape. Prime, is a free flowing side not affected by the vacuum and fuel can flow regardless of bike running or not.

That all said:

If you have that much gas in your carbs, and it's selling out of the top, you have at least the following issues:

- at least one float is sticking open and you're flooding
- your petcock is leaking and gas is running even when your bike is off.

**if you have that much gas in your carbs to overflow, it's probably run into the cyls, and down I to the crankcase, too, and polluted the oil. Open the oil filler cap and sniff. Smell any gas? Gotta drain it, and replace that, too. It may have already backed up through the crankcase vent tube, and filled your airbox and possibly filter too.... Open your airbox and check. Is it dry, or swimming in oil/gas? Dry/or light "mist"- good, wet/ swimming.... Service THAT, too.

Getting back to your pic of the little screw you asked about ( the red pic). That's a screw for the butterflies. Hopefully you found that out before installing the carbs.

In not sure the tube retainer on the upper rail, shown in the second pic, is in the correct location

 

+1 to all the above.

 

you have to love inovation

 

I've been wondering if I connected my hoses properly when re-installing my carbs and I think I may have done it incorrectly. Doing a little research, it seems that the fuel line is suppose to come from between carbs 2 & 3 from a spot about idle adjust knob and that would attach to the petcock ( I labeled my picture "1") but my question is what is that spot in pic 2 for? For reference I have an XJ700 with Hitachi HSC33 Carbs.

I've also started doing some of the things Hogfiddles suggested so thank you for that.

 

You shouldn't have a fuel nipple located there (picture 2). I have a similar rack of carbs in hands at the moment and mine does have a block-off plug there.

Also, the fuel intake T-port is supposed to be located between carb #1 and #2.

 

Between carbs #2 and #3 is correct for the HSC33 carbs (only the HSC32's had the fuel inlet between #1 and #2).

That large vac port on the left side of the carbs is for vac synching purposes only; during normal operation, those get plugged up.

 

On the petcock, the big port ( circled) is for your "fuel line out to carb " line. The small one whine it is your "vacuum line in from the manifold vacuum port" line.

Also, the hat on carb one is not right...... And im going to take a pic of my rack for you .... It may help

 

Thanks, I would really appreciate that.

 

MattiThunderrr pleeeese chime in before I do........

 

He's probably still over at the "idle at 6000rpm" forum laughing hysterically.....

 

Dave's rack always helps!