Carb trouble - 85 XJ700N

Hey all -

Coming back to the group after a while away. Too many frustrations in life to deal with ficing the bike, but now I am ready to GO, GO, GO!

HEre's my dilemna - I have an 85 XJ700N and when I fill the gas tank, a gas and oil mixture pour out of the bottom of the air box and from the tube leading from the carbs. I am comfortable taking out the carb rack and cleaing the carbs inside an dout - no issue there. I believe the problem is a hung up float OR a dirty carbs where the float needle will not shut off the flow of gas. My BIG problem is - HOW DO I SET THE FLOAT HEIGHTS AFTER I CLEAN EVERYTHING? Any help would be most appreciated!

 

I would like t think this gentleman recieved the jelp he was looking for? ridz.

 

Take a look in my photo gallery and see the setup for checking float height using the clear tube method. For a Mikuni you will need 1/4 inch o.d. tubing to fit inside the float bowl drain. Open the drain screws and let the fuel fill the tubes. When the bowls are full the float needles should shut off flow. If a tube keeps rising and the float is stuck open it will rise until the fuel spills out the carb throat. Drain the fuel from the carbs and remove the bowl on that carb. On the float is a tab that the wire of the float needle fits on. Bend it "slightly" toward the needle. This will close it sooner. To make sure it is seating you can take a wooden golf tee and spin it in the float seat to polish it. Spin it back and forth several times using moderate pressure. Then repeat the fuel in the tube routine and see if that fixes it. You may have to do this several times to finally get the float needle to seat.
Another thing that can make the float stick is rust on the float pin. Make sure it is clean and smooth. The float drain screws are known for being stuck and sometimes seized in the bowls. So make sure they are free before starting this. They can be loosened with heat applied to the screw from inside the bowl and an impact screwdriver. Most impact tips will have to be narrowed down some to fit well. I will check back for any questions you may have and don't hesitate to PM me.

 

does this bike have a vacuum petcock ?
on - prime - reserve and two hoses

 

maybe thats why he is not reposting ,pollock!

He found out what pri stands for?

could be ,maybe I dont know .....

 

Yes, Polock - it does have a vacuum petcock - on - pri - res and two hoses. I donot know what 'pri' means, but I am willing to learn!

Bigger problem - I removed the carb rack and took off each float bowl. Some sediment, but nothing terrible looking... EXCEPT for the one broken tab where the pin holding the float in place was broken and re-secured using a goop of silicone! I had a spare carb rack and proceeded to s-l-o-w-l-y remove the one carb off of each rack and trade every part in the broken chassis to the good carb chassis. Put the "new" carb back on the rack, sprayed down every float bowl and reinstalled the rack. Flushed out the gas tank and put in one gallon of gas with two ounces of Seafoam. Started the bike - and is proceeded to back fire plenty, have close to zero power, and then started pouring a gas/oil misture out of the air box. Took off the gas tank and took off the carb rack again. It is now sitting because I am hesistant of what to do next. I purchased carb kits (4) and have read Dwayne's carb cleaning post front to back, over and over. I will go ahead and do this, unless someone pipes up and tells me that I am missing a different solution to this problem.

 

Just another note - when I took the rack off, only the carb that I changed off the rack was wet - i.e., the throat leading from the card to the intake manifold was wet with gas. The other three were dry.

 

Ok, so I took the float bowl off of the wet carb and installed a brandy-new float set. Adjusted the tang so I KNOW the float needle is closing. I want to adjust all of the float heights before putting the rack back on the bike and trying it out, however - - - I do not fully understand the post that explains how to adjust the float heights. I have printed it and read it, but placing the tube next to the carb and allowing it to fill with gas... where should it read as a proper height? How do you manuever the clear tubing to get a correct reading? When the specs list the float height (as measured with a "special tool"), how do you measure that height? I am a complete novice when it comes to this, but I want to learn so I can repeat this process again as time clicks away.

 

From the XJCD Yamaha’s manual states:
Place motorcycle on level surface.
Use jack under engine to ensure the carburetors are positioned vertically.
Connect fuel level gauge to the drain nozzle.
Loosen the drain screw and start the engine.
Check fuel level one carburetor at a time.
Fuel level is measured below the carburetor body and should be 1.0 mm +/- 1.0 mm

It is a pain in the butt to put carbs on, check the level as described above, take carbs off to make adjustments, reinstall, check again, etc etc etc

Some of us have bench set the levels using jigs to hold carbs level and a small container of fuel hooked up to flood the carbs.

Try this thread to see what I came up with ( since this link posted I realize the carbs should be vertical to set fuel level ).....
http://www.xjbikes.com/Forums/viewtopic ... level.html

The alternative way to adjust the float level is to follow this info:
With the carb float bowl removed.
Hold the carburetor in an upside down position.
Incline the carburetor at 60 ~ 70 degree angle ( so that the end of the float valve does not hang down as a result of float weight )
Measure the distance from the mating surface of the float chamber ( gasket removed ) to the top of the float.
Float Height: 16.0 mm +/- 1.0 mm
NOTE: the float should be just resting on, but not depressing, the spring loaded inlet needle.



Float height adjustment step:
Remove the float.
Adjust float height by bending the float tang slightly.
Repeat the procedure for other carburetors.

 

You should do the adjusting of Float Heights with the Carbs OFF the Bike.

That way ... if an adjustment is necessary ... you don't need to be a contortionist and have Gas get all over everything.

Here's a Quick way to get them done without alot of fuss and muss.

Drive some long nails into a wide board you have nailed-up to the wall.
Slip some rubber hose over the nails for "Traction" and "Non-scratching"
Place the Rack on the Nails and get everything Level.
Tether the Rack so it can't fall-off and ruin your life.

Fill the Bowls with Windshield Washer Fluid.
Do the "Hose Trick"
Mark the levels with a Sharpie.

Any one's that are GOOD ... Mark with a Smiley Face or something.
High or Low ... Put an "X" on that Bowl and Indicate High or Low.

Drain 'em.
Hit the bench.
Pull the Bowls needed.
Adjust.
Retest.
Etc.

When they are set to:

The LOW Part of the Fluid Line reaching the spot between the Bowl Securing Screw and the bottom of the Washer above it ... You're IN.

Drain.
Remove Drain Screws.
Attach small end of Little Funnel to Supply Hose with Duct tape

Hair Dryer -- LOW Speed ~ LOW Heat
Blow-out moisture.

Done!

Get the Drain Screws in them Bowls
The Carbs back on-the-bike

Hit the road!

 

Will do - thank you Nick and RickCoMatic. I will post after I get them adjusted, on the bike and started to let all know what happened... hopefully something good!

 

One little quirk I discovered with setting float heights on the bench is that if you have the rack perfectly level, it results in low heights when mounted on the bike. I could figure out why I kept getting lean mixtures until I measured the float levels on the bike. They were LOW. So I readjusted them by mounting them in the intake boots and checking the heights. So I got them at the right levels while mounted in the intake boots. Ever since then...no more lean issues on my 550. So just stick the rack in the intake boots on the bike to double check your levels before you go putting everything back together.

good luck, and ride safe.

 

Ok, I have read PghXJ's type of comment before on this forum (tilting the carbs to mimick the angle they are on the bike VERSUS keeping them strickly level - when adjusting float heights)... which IS the correct way?

RickCoMatic - I wanted to do your "No fuss, no muss" hang-it-on-the-wall, but I do not have a funtional garage. I did make a jig like Nick had posted in a previous post. Had to stop when I finished the jig to go to work! But, when I am back home, I will get some clear tubing and start the process... If the bike runs without leaking gas or oil, I will be a happy man. Then I can move onto figuring out what to do about dialing her in... I have no Colortune or YICS, etc... we shall see.

 

Ok, did the "Hose trick" on the carbs with the rack off the bike, focusing on the one carb that I had replaced - to set the float height. Even after finally getting the fuel level to where RickCoMatic said to, every time the carbs fill up with fuel, gas pours out of the t-fitting between the 3 and 4 carbs (I had replaced the # 4 carb). EVERY TIME! I bang the #4 carb with a screwdriver and it stops flowing, but I obviously KNOW it's NOT supposed to do that! I am trying to contain myself on this forum, but I am so pi$$ed right now - I had to drain the carbs and put it all out of my sight. All I wanted was to get the carb float height adjusted so I could put the stupid rack back on the bike and see if it would start. Now all it wants to do is spill gas everywhere. I am sick of it for today.
Could it be that I have to check all the other three carbs float heights to make sure they are not set too high? Or should I just pull everything out, clean everything from top to bottom, put in the other three float sets I have and then set the float heights? I was trying NOT to touch the other three carbs, as they did NOT appear to be leaking at all, but now I do not know.
PI$$ED!!!!!

 

OK ...

Obviously, the Float is STICKING.
Why?

The first clue is that it's in a replacement body.
But they are all the same.

First, have a look at the type of Position Retaining Wire on the Float pin.

If its a "Full Box" type, that wraps Up, Over and Around the Float Tab ... look at it VERY Closely to see that it hasn't been bumped out of square.

Remove it and rotate the BOX -- 180-Degrees; anyway.

If it's the "L - Type" -- Make sure that the "L" part is square.

Hold the PIN with your FINGERS and Very lightly run a small strip of 1500 Paper down the Center Locating Ridges.

Cut a narrow Triangle of ScotchBrite (Medium Gray) Pad and push the point of the triangle into the hole of the Float Valve and twist and "Screw-in" as much of the Pad as possible.

Do the Twist.
Reverse twist and screw it OUT.

If it leaks now, the Float ain't no good and further messing with it is going to raise your blood-pressure so high you're likely to Pop the Safety's and become enraged.

 

A suggestion when setting floats:

I put new needles and seats in mine this week. Before changing them I inverted the carbs on the bench, removed the bowls, and measured the distance from the bottom of the floats to the gasket surface on the carb body.

After putting in the needles and seats I set the floats (again inverted) so the distance from the bottom of the float to the gasket surface was the same as with the old needle/seat.

I use two old carb holders screwed to the front of my bench to hold the rack - with an elastic strap pulling on them to eliminate the sag.

I put the fuel tank on a box on the bench with a length of hose to the carbs and set to PRI. I scribed a line at 3mm (which is the correct height on a 650) on one bowl (rack is level). Checked each bowl to that scribe line. HORRAH - spot on!.

However, if any had been off I'd have measured and recorded the correction needed (I had a piece of paper numbered 1 2 3 4 all ready). I then would have pulled the bowls, measured from the float to the gasket surface as above - calculated the correct distance by adding/subtracting the correction for that carb and re-set them. Much better than guessing and going through the filling with fuel and pulling apart again. Of course you should re-check the fuel level after setting the floats.

 

I will tackle them again either tomorrow (Monday) or the next day. I do have three other float sets, for the other three carbs, but if the one I installed is bad, I'll "steal" one of them. What's really bothering me mentally is that the carb is doing the same thing it did before I changed out the chassis - allowing fuel to pour out if it. It's like me changing out the chassis (in order to remedy a broken float post) did NOTHING! I-R-R-I-T-A-T-I-N-G, to say the least. I will "take it on" when I can remember how much I love the bike again.

 

Leaking at the T fitting is an o-ring problem, not a float valve problem. Did you replace the orings when you did a carb body swap? I tried to reuse my old oring on the brass fuel lines and will say they all failed misserably.
If it's the float needle I would expect the fuel to be flowing out of the throat of the carb body not the T fitting. Banging on the carb body is usually used to jiggle the float needle and allow it to seat. I would look really close at where exactly the fuel is coming out of and go from there.

I think you would be wise to check the fuel levels of all the carbs while you have it off the bike. Could save some cursing down the road and you will know what the levels are at without having to assume!

Again you have the carbs out of the bike now, cleaning them all may be an idea. What condition was the original carb that you replaced? Did you strip it down and have a look for deposits?

If the other carbs were leaking they would be dumping fuel out of their own throat bodies, not out of one of the other carbs!

 

I got pretty angry with my carbs too so we all know where you are dude! Take time and chill then do just what Nick said. The orings need to be changed on the T fitting. Forget about the floats for now and just go after the orings. Secret on these problems is to concentrate on one thing and not all things. Do one and celebrate then do another and celebrate. Which with us usually means have a beer upon the small victories.

 

Nick -
Indeed, I did NOT replace the O-rings that were on the small connector fittings between carb's 3 and 4 - they didn't look great, but when I tried to find new ones that were the same size, I couldn't find any, so I reused them. Maybe that is why fuel is leaking out of the "T" fitting between carb's 3 and 4, like you wrote... guess I may have to take that carb back off the rack again and find those O-rings.
Yeah, I am going to check the other three carb float heights.
Yeah, I will probably just go ahead and clean the entire rack, inside and out.
No, the other three were not leaking fuel out of their throat bodies, so I think the only culprit is the # 4 carb.
The bike sat for at least two years (per the PO), but when I initially took off the float bowls, they were surprisingly clean! No way would I have guessed that the bike sat for any amount of time really, at all. That's how clean they were. Now, when I got the Emulsion Tube out of carb # 4, that was a different story...

 

BlueMaxim - I am taking that secret to heart - and my fridge is full of Yuengling and Bud, so I am all set for a long night....

 

That's the spirit! It's what I had to do. I pulled my carbs about 7 times before I got it right. The set I just rebuilt were a piece of cake. Experience is necessary but getting it is the PIA of paying your dues. That's why I post here and try to help. I was just as frustrated as you are now and had it not been for MountinMan (who is now deceased) I would have given up. I now have ridden that bike with those carbs to 2 carb clinics and have tuned many bikes and am always overjoyed when I see the owner smile! I just love doing it.

 

Check with Yamaha on those o-rings, they still had them available when I needed mine last year.
As BlueMaxim said, one step at a time and things will go a lot smoother!

 

carb frustration here too man. I feel ya. I've had them apart more than a few times and cleaned them out. It runs great...however I still have the problem where when I pull in the clutch at a stop sign or light the rpms sit somewhere between 1500 and 2000rpms for 2-15 seconds before settling to 1100rpm where the idle is set. Floats are spot on, passages are clean, pilot screws have been tried at 2.75, 3.00 and just in between...still there. Throttle cable snaps closed HARD, so it isn't sticking.

Figure that one out and I'll give you a cookie. It is pi$$ing me off.

Just be patient and it will come in for you.

 

You have Diaphragm Pistons that are sticking.

This will be evident if you can't "Find enough RPM 'Behavior' for confident slicing-up twisties"

If that is the case ... search: "Clunk Test" by yours truly.

 

they drop like a brick with a loud clunk. I used 1500 grit on the slides and the slide holes. I also checked the diaphragms by holding them up to a bright light to see if there were holes....nothing.

 

Have you done a colotune and carb sync?

 

the sync is even all the way across...and the mixture is running well. I tried making it a bit rich (pilot screws) and it didn't fix it...tried going the leaner way...same thing.

this is why I am soooo confused.

 

try backing off the idle screw. Ity is underneath the carbs. Just a touch, about half a turn. then try the motor after it is warmed up. Keep backing the idle screw off until the idle drops fairly fast and bingo, there you have it. You may need to recheck your sync after that though. Goot luck.

 

I noticed that if I moved the idle screw back a bit...just a touch, it got better, but I never kept doing it. Perhaps it is set too high. I'll give it a shot before I leave here today.

I have the Experienced Riders Course day 1 tonight with the bike...More learning for me.

 

Have fun!

 

Course was a lot of fun. Turning the idle down by about 1/8-1/4 of a turn fixed the problem. The idle no longer hovers and bobs...I guess it was just a bit too high. So not the bike is 100% fun to ride as opposed to 90%. Plus the instructor used to have an 82 Maxim 550, so that was all we talked about.

So to the OP, did the carb trouble on your XJ700N get worked out?

 

Not yet - trying to locate replacement O-rings for the connector tubes between carbs # 3 & 4 before I put it all back together and set the float heights. I want to try everything I can to make sure it doesn't leak, so once I find those, I'll start piecing it all back together.

 

STAY TUNED! HAHAHAHAHAHA

 

PM chacal. He is selling all kinds of parts for Hitachi carbs and some for Mikuni. I know he has the o-rings for the fuel supply tubes between the carb bodies for the Hitachi carbs.

Here is his post

Hist most up to date list is on page 3

 

Hardware store may have your o-rings. I think they are 110's. You can also take the t fitting down with you and test fit a few different sizes.

 

Orings are easy to get from mcmaster.com. You will need the wall thickness and i.d. You can buy 25 in Viton or 100 in Buna-n for about $5 US.

 

You can find the O-rings at Plumbing Supply Outlets.

Use a Q-Tip and wipe the O-rings and the Inside Diameter of where they fit on the Carb Body with some Marvel Mystery Oil or Clean Brake Fluid.

Get the Parts lined-up so you wont have to separate them once you press the parts together.

I hope your leak stops. The new O-rings should do the trick.

I hope so!

 

yeah I noticed on my carb rack that when the carbs were rebuilt by the PO, they must have separated the rack because instead of changing the o-rings it had gray RTV all over the pipes to try and seal it. Well the RTV has mostly fallen off, but it doesn't leak, so maybe when they had it professionally rebuilt, the o-rings were changed.

o-rings are everywhere, nearly every hardware store has a rack with drawers full of them.

 

Thanks all - work is crazy right now, so it probably won't be until Friday when I really get to tackle these carbs again. Is it illegal to work 26 days in a row in NJ? :-|

 

Lizzen, few godda prablum woikin' twennie-sizz days inna roe ... maybe I kin fine sumbiddy dat ain't gonna bidche 'bodd id.

Huh???

Smadder widge-jew? Ennie-how??

Gidd ovva-dere ann stard actin' liag gue wanna woik' duh hole munth fa free!

Hi-god ger yamaha ride-ear. Fugg-ed-uh-boude-idd!!!

 

If I had kits for all 4 of my carbs, I'd put them in while the rack is out.

If I were changing out the clutch on my pick up I sure would replace the throwout bearing while tha whole thing was apart.

 

If I had kits for all 4 of my carbs, I'd put them in while the rack is out.

If I were changing out the clutch on my pick up I sure would replace the throwout bearing while tha whole thing was apart.

 

If I had kits for all 4 of my carbs, I'd put them in while the rack is out.

If I were changing out the clutch on my pick up I sure would replace the throwout bearing while tha whole thing was apart.