I give up! (on the carbs)

:evil: I have disassembled and cleaned the carbs on my 82 xj750 seca 4 times. If I have to take them off my bike one more time i'll kill myself. However, after all this I still am having a major issue with my bike. Basically my bike revs way too high. Even if I back the idle screw all the way off it still spikes up to 35-45 hundred rpm. I polished the slides with rouge and it passes the clunk test with ease. There is not a drop of dirt anywhere in the carbs. I bench synched the carbs twice. The mixture does smell rich but i do not have a carbtune which i understand is neccsary to adjust mixture. This is my first bike and really my first time working on any form of motor at all so i'm in the dark at this point. Am I better off taking it to a shop and spending the hundred bucks or so to have it professionally tuned? or is there something that i am missing? Thanks.

 

What does this mean? Is it "idling that fast", or does it hang there if you rev it?

In any case, you should be able to turn the idle stop screw down until it dies when the throttle is released.

Either "choke" isn't closing or something is holding them open.

Here is how I'd tackle it:

1) Make sure the "choke" lever works the enricheners and the throttle works the butterflies.

2) Make sure all the little enrichner plungers are closed when the "choke" is turned off. There should be some slack in the cable and a all the forks that lift the plungers should have some free play.

3) Twist throttle to wide open position and release. Should snap back with authority.

4) Loosen the throttle cable by tightening the screw barrel in the cable just below the throttle grip. There should be a ton of slack in the cable at the carbs.

5) Start the motorcycle. If you cannot back the idle down using the idle stop screw then your butterflies are either sticking or it is too far out of sync.

If you get all the way to step 5 you need to pull the carbs again. Listen for the butterflies snapping shut as you remove them. Make sure the idle stop screw is backed out until it doesn't contact the mechanism.

Hold the carburetors up to a light looking through from the rear. There should be no light shining through at the bottom of the butterflies under the slides. There probably is just a bit up near the shaft if you hold them at the right angle. This is ok.

If you have light under all the butterflies then something is sticking. If there is only light under some of them the closed one(s) are holding them open. Tweak your sync until they're all dark.

 

Let me add to Micarl's excellent advice.

Push down on the throttle rail (push on the sync screw) it's another way to see if the butterflys are closing. Mine was not and I found the spring on carb 3 was in the wrong place and not providing the right pressure.

If you do all suggested above, your butterflys are closing and you still have high idle you have air getting in somewhere. Have you replaced the throttle rail seals? Also check the vacuum caps on each of the carb to ensure they are tight.

Hang in there I had mine off 3 times then finally did a complete rebuild which resolved my issues. You cna get all the expert help you need on this forum.

 

This could ba a simple as you having Bench Synced the Carbs with the Butterflys too far open and now they are letting Main Jet Fuel and Air get into the game.
That's why I suggest Bench syncing the Throttle Plates with a slice of Business Card.
The Throttles are nearly closed after getting them mechanically Synced.

There must be something causing your linkages to be opened slightly.
Generally, after doing an overhaul, unfamiliar hands will get the Cable Attachment Point at the Carb Linkage snagged under the rear of the Cylinder Head.

This causes the Linkages to tilt open and revs to go wild when you fire it up.
That, plus the Throttle Shaft Seals can be so well cleaned that they need a drop or two of Light Oil in them to restore the smoothness in their pivoting in the Body.

 

g*d d****t. You dont understand how much i did not wanna take the carbs off again. Is there some trick to getting the boots from the airbox back on? My girlfriend has been walking around with her wrists all bruised from sticking her hand through the airbox to help push the boots on. (my hands don't fit). I'm considering taking the carbs to a shop and having them tuned there. How much would that cost me would you guess? I'd like to have this bike on the road within the next week or so. Thanks for all your help guys.
***Edited By Robert, mind the language please! Thanks!***.

 

i had to have my girlfriend pushe the boots through as well(them airboxes are tight). And double check to make sure the throttle and choke cables are seated and screwed in where they need to be, i fought for a little while with my throttle just to find out it wasnt seated into the slot properly.

 

Well you have to take them off to fix them you can't avoid that.

Hard to describe hoe I get the boots back on but I'll try. I push the boots into the airbox to remove the carbs. I reseat them by pulling the #2 or #3 first. I work the airbox seat back on by squeezing the boot slightly and working it all around. To get it back on the carb I use a dull dental pick to pull the flange around the carb body. It's a royal pain but there is no way to avoid it. I have never had the need to have anyone reach into the airbox although I can see how that would be helpful.

I'm not sure I would trust a shop, but I'm cheap and I want to know exactly what was done.

 

Crap, i'm not looking forward to ANY of this! My carbs are getting cleaned now...

 

I had an 81 in the shop for carburetor work. Those air box boots were so supple it was a breeze to put them in. I could pretty much wad them up and then just bend and push them any way I wanted. When I did them I reached the conclusion we've all been fighting dried out stiff boots.

Might consider replacements.

 

BOOTS-BE-US!:

RUBBER AIR CLEANER BOX-TO-CARB BOOTS & RELATED:


af3) OEM and reproduction Air Cleaner Box-to-Carb Rubber Joint or "Boot", both original and reproduction individual boots and complete sets are offered to allow you to replace cracked, dry-rotted, melted or stiff-as-a-proverbial-board originals. If these boots aren't flexible, you're going to have a fight on your hands when you go to re-install your carbs! And if they're leaking, they will upset the air flow into your carb(s), not only making carb-tuning efforts difficult or impossible, but also allowing dirty, unfiltered air into your carbs and cylinders. These are the boots that run from the air cleaner box to the rear of the carbs!

HCP558 Air Cleaner Box-to-Carb Rubber JOINT OR BOOT, for all XJ550 models, each:
$ 14.50

HCP558SET4 Air Cleaner Box-to-Carb Rubber BOOTS, set of 4:
$ 53.00



HCP559 Air Cleaner Box-to-Carb Rubber JOINT OR BOOT, for all XJ650 (except Turbo) models, each:
$ 11.50

HCP559SET4 Air Cleaner Box-to-Carb Rubber BOOTS, set of 4:
$ 44.00



HCP561 Air Cleaner Box-to-Carb Rubber JOINT OR BOOT, for all XJ700-X models, each:
$ 10.50

HCP561SET4 Air Cleaner Box-to-Carb Rubber BOOTS, set of 4:
$ 39.50



HCP563 Air Cleaner Box-to-Carb Rubber JOINT OR BOOT, for all XJ900 models, each:
$ 14.00

HCP563SET4 Air Cleaner Box-to-Carb Rubber BOOTS, set of 4:
$ 54.00



af4) OEM air cleaner-to-carb boot metal CLAMP RING, includes the cinching screw. These are used on the carb end of the boot only.

HCP565 OEM air cleaner boot metal CLAMP RING, for all XJ550, XJ650 (except Turbo), XJ700 non-X, and XJ750 models, each:
$ 11.00

HCP565SET4 air cleaner boot metal CLAMP RINGS, set of 4:
$ 39.00


HCP566 OEM air cleaner boot metal CLAMP RING, for all XJ700 -X, XJ900, and XJ1100 models, each:
$ 6.00

HCP566SET4 air cleaner boot metal CLAMP RINGS, set of 4:
$ 22.00

 

You'd think someone calling hisself BOOTS-BE-US! would have boots for an XJ750 Seca, but none in the offered price list.

 

Replacing the Boots is a pain.
No doubt about it.
Do a few things to lessen the Pain.

Sand the Airbox holes smooth with some 400 Paper.
Wrap the Boots in a wet towel and microwave for 40-45 seconds.
Grease the locking channel groove on the Boots to allow you to rotate them easily upon reinsertion.

Make a shoehorn tool to be used to guide the Front Lip of the Boots around the outsides of the Carb Intake Horns.

Do the two inside ones, first, and finish-up with the outboard ones.
As painful as it is to have to deal with the Boots, NOT having to deaal with a broken-off Manifold Cap Screw outweighs the inconvenience.

 

Get a tube of Syl-glyde silicone grease at NAPA to use when installing the carb boots. Use this stuff applied sparingly on the mating surfaces, makes the rubber boots slide on and off much easier, and seems to soften the rubber a bit. In addition, it doesn't degrade the rubber boots.

 

I should note my boots look to have been replaced and are not stiff so I may be having a much easier time of it...

 

Where are the throttle shaft seals??

 

The Throttle Shaft Seals are in the sides of the Carbs at the fulcrum point where the Throttle Shaft rotates.
Each Carb has two. Left and Right.

 

Thanks, just curious.

 

I'm doing a set of XJ carbs today and I remember something I forgot to mention.

On the boots it's easier to do #3 from the left because the clutch cable is in the way from the right. I take #3 off last (from the left) and put it in first so I can get to it.

 

well i think have my problem is that i purchased the bike without boots. So, in an attempt to preserver the almighty dollar i used plumbing tube and used a razor knife to fit it to size. So it is very stiff and hard to work. My patience for carb problems is finished however and i've decided to make this a mechanics problem.

 

i have the carbs on and off 1/2 a dozen times brother
i know the pain
i used silicone spray on the boots and air horn
slides on pretty easy now...
i also used a crobar and was very carefull..
but its easy as pie..
now if i can get the d@m things to work i will be in buisness..

 

yea pretty much the point i'm at. I'm going up to boston on sunday to hang out with rickomatic and see if he can't help me get the damn thing running right. I just finished my riding class and i'll have my permit tuesday. I'm dying to get out so it's killing me that i'm having these problems.

 

I have the whole Emergency Room Staff on call. Code Blue. There's an AutoZone within a mile. A Liquor Store and Deli within walking distance. The Fire Department is only three blocks away ... so, I figure ... I'm ready for the challenge.

I think we're going to straighten-out the problem and send the patient back home to Rhode Island alive and kicking! Should be a day to remember!

One for the books!

 

Yeah Tommy, if RickCoMatic can't help you figure it out, it's time to take the bike out behind the barn and perform an "old yeller" on it.