New Member/New Rider (and more carb problems!)

I just recently (as in last weekend) bought myself a XJ550 Seca off a guy in St.Louis, MO and after doing some light internet surfing I found these forums. The XJ550 is my first bike, the only thing I ever rode before was a friends scooter. The XJ definitely has more power, and I have to admit I really like it.

Anyway, when I bought the bike the guy admitted that it was not exactly perfect, the fork seals were leaking pretty bad. Also, he claims to have had the carbs rebuilt a few months ago. From the stripping on the screws, and the fact that the inside of the carbs are pretty damn clean I am assuming that he did have them cleaned. However, after having them cleaned he left the bike in his garage for three weeks without running it. So when I went to see the bike in person it was having trouble idling, it kept dying off when it got too low.

Aside from those two problems the bike is in amazing shape from what I can tell. Only 4,480 miles on it, the paint is pristine, and all the chrome is shining with very little blemish.

My problem is this, I brought it home and decided to have the fork seals replaced before they leaked on the breaks, and while they were out getting replaced I decided to take a look at the carbs to make sure all was well. So I started taking them apart (with lots of help from the Service Manual and even more help from pictures/posts on these forums) and found one of the Vacuum Diaphragms had a one or two centimeter tear in it. The rest of the carbs look very clean, only one of the jets was a little clogged the rest were pretty good. So I am wondering if all of the idling problems I was having could have come from the torn diaphragm. Could that be? Is there anything else in the carbs I should check before I go off and order some parts? Also, are there any aftermarket Vacuum Diaphragm/Piston Assemblies that may be cheaper then the OEM parts?

 

pretty sure that the tear in the diaphram is causing your idling promblem. if you only need one diphram it is best not to get aftermarket parts. it wouldnt cost very much for the name brand part, it would be worth the investment in the end. the only other thing i would check in the carbs would be jet position and size, both for air and fuel jets because somebody has had them apart and you can not always believe what someone you bought the bike from may or may not know.

 

Thanks for the fast response. Looks like I am gonna go ahead and order the Diaphragm/Piston.

I am glad I managed to talk the guy down in price because once I buy the diaphragm I will have spent as much money as the guy originally wanted for the bike.

I am already missing riding the bike and I have only had it for three days, and now it is gonna be out of commission for even longer. Hopefully I can get it back on the road in the next few weeks.

 

FEW WEEKS! man the work you got to do wont take you 2 hours at best. one more thing before you put the carbs back on make SURE your carb to manifold boots are not cracked and have a air tight seal to the manifold or you will pulling off carbs again. trust me been there.

 

The weeks was including shipping time. If I prepare myself for long ship times, then I am happier when things arrive early.

I actually just went out in to the garage and looked at the manifold boots, and they are slightly cracked, looks like I gotta get those as well. Better to do it right the first time though.

Is there a trick to getting the carbs back on the bike? When I took them off I was trying to figure out how I would get them back on, and it seems like I may have to take the air filter assembly off to get a nice snug fit on them.

 

no it is not neccessary to take the air filter box out. Put in and pull out the carbs through the left side of the engine. if the boots are slightly cracked that is normal, mine are that way, just make sure the crack does not go all the way throught the boot. The boots are pretty thick. It is a good idea to spray a little armorall on the boots to shine and proctect them from the elements, especialy the outside boots. Use a wooden handle like the one on a hammer to help you pry the carbs back in the boots. You can put a little vasoline on the insides of the boots to aid you in installation.

 

So while the diaphragm was out I went ahead and took a picture of it. Here is what the tear looks like:

Sorry for the blur, the pictures are from my phone.


Also, while I was looking at the intake manifolds I noticed that one of them did not have a cap where the carb sync tool would be attached, but rather a hose...which I don't remember disconnecting from anywhere. Is this hose supposed to be here? And if so, what it is supposed to be (re)attached to?

 

That hose should connect to the gas tank on your fuel petcock. I can't be sure which one. The petcock works off vacuum and that supplies the vacuum to it.

 

The vacuum fitting will be the smaller of the 2 nipples on the petcock I do believe...it is on my Maxim anyway.

 

Thanks for the info, I will probably be ordering the parts I need this weekend from XJ4Ever and installing them once they get in.

Edit: Any tips on getting the gaskets off of the intake manifolds? They are very much stuck and I want to go ahead and replace them while I have easy access to them.

 

I used a utility knife blade to get my gaskets off the intake boots. Came off easy, careful blades are shartp LOL

 

Armor all is not necessarily the best thing for rubber...or dashes for that matter. It attracts dirt and dust and can actually dry out the rubber over time.

 

The tear in the Diaphragm will cause you problems. Maybe not so much with IDLE.
Repair those Cracks.
Use LIQUID ELECTRICAL TAPE.
Unscrew Top on Bottle.
Cut-Off and discard -- Dapper.
Cover bottle.

You need:
Knitting Needle
Artists-style Paint Brushes
Small Funnel
Masking tape

Hack the Nozzle of the funnel off with a saw. Make a FORM that you can use to SPREAD-OUT the Diaphragm on to and TAPE it Smooth and Flat.
Open Bottle
Insert Knit Needle
Collect MINIMUM Amount of Liquid Tape.
Drip on to 3 X 5 Card. 2~3 Drops ... Dime sized.
WORK QUICKLY
Use Artist Brush -- Get the Dropped Product on the Brush
Paint the Product on the Diaphragm Area to be Repaired.
The INSTANT that The Product -- "Pulls" -- STOP
Throw-out the remaining Product on the Card
Put the Brush in Carb Cleaner
Start a second application with ALL FRESH STUFF

The "Drill" is like this:
Open Bottle ... Knit Needle ... Cover Bottle ... Drip on Fresh 3 x 5 Card or Paper ... Collect Drops with Paint Brush ... Brush-on Product ... Use Product UNTIL it begins to 'Pull' ... Stop application ... RELOAD.

Each repair gets at least 2 coats ... BOTH Sides.

Yello Plastic Funnel with Nozzle Cut-off and Diaphragm Piston Inserted in the Hole where the Funnel Nozzle was removed: