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1 cylinder cutting in and out (SOLVED)

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sat Jun 22, 2019 6:18 pm

Bstig: My enricher is simpler than that one but similar. Cover, spring, diaphragm with plunger and that's it. I blocked the vacuum port and added a neoprene washer to the plunger to sit on the inner part of the thing hopefully to stop it from passing gas (!) through the housing. Quick test run says it starts easily with some help from the choke, idles smoothly, drives well accelerating strong and smooth, cruise is uneven, front cylinder is a bit rich and the rear cylinder is a lot rich with the plug becoming pitch black after a bit less than a mile. This is pretty much how it was before I went after the enrichment widget.

It seems that whatever I did to the enrichener,had no effect and whatever was wrong before is still wrong now. I checked the main jet and it is the correct one. I'd check the float levels, but the drain screw thingies are broken and I have no idea how to get them out to replace them. I am tempted to cut a window in the float chamber covers and epoxy in a small sight glass. I'm just not sure this would be useful at this point.

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Re: 1 cylinder cutting in and out

PostAuthor: Arjay » Sat Jun 22, 2019 8:09 pm

I think that the "coasting enricher" diaphram is controlled by vacuum (so I believe) and a permatex fix will work. No gas exposure. I think Its job is to allow plunger to do a little squirt on quick deceleration preventing or minimizing that annoying backfire.

Seeing as yours has hole and that is wrong even a temporary fix would be worth doing just for the sake of seeing results.

When I first got my xv1100 I had to struggle with the carbs. It gets easier. I finally dedicated a 10mm box end wrench to the cause by torching the wrench red hot and bending an angle on it. Made the job somewhat easier as somehow I always have to remove the boots. The one fear I got over was worrying about tearing the boots on remove/install. Use lube. When you push one side hard you can leverage the other side edge with flat screwdriver blade...

I also silicone the boots and silicone the vacuum access caps on those tubes for when doing synchronization. A backfire might pop them off...

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sat Jun 22, 2019 8:27 pm

One more thing I noticed is that the slide needles are different from "cylinder 1" to Cylinder 2". The cyl 2 needle is set to be leaner, but which is which? Is Cyl 1 the front or the rear?

The needles I have are the right ones per the book.

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sat Jun 22, 2019 9:02 pm

Arjay: I got tired of fighting the intake boots and replaced them both with 2 in PVC pipe. The ID slips over the carbs snugly, and the outside can be machined to fit snug in the backbone ports. Thus I simply slide the sleeves up completely out of the way to remove the carbs, then back down when I'm done. I suppose metal tubing would work and be less prone to breakage. Tube wall thickness is thin, I'm guessing about .020 or so.

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Re: 1 cylinder cutting in and out

PostAuthor: Arjay » Sat Jun 22, 2019 9:03 pm

my slide needles are set same depth on both.

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sat Jun 22, 2019 10:28 pm

Per Clymers, slide needle part numbers for the 1987 XV535:

Cyl 1 - 5dz7-1
Cyl 2 - 5dz8-1

They install to different depths. Lower depth = leaner which explains why my rear cylinder is running richer than the front. To my mind, they're both running too rich.

UPDATE: Ordered 2 new needles. I notice that the part number variation for front and rear has disappeared as well as an additional part number change for a new model application, 3BM-XXXXX for XV535's up to '94. I expect I'll see them later this week as they have to ship from faraway Lincoln NE. :;:

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XV535 Running Super Rich

PostAuthor: Billll » Sat Jun 29, 2019 2:14 pm

Got the electrical problems pretty much sorted out, but the bike is running super rich, blowing black smoke and fouling both plugs in under a mile. Fouls the rear cylinder first probably due to the needle being richer in back, -8 vs -7. Newer carbs have identical needles and I have ordered a pair, but this seems like there's a passage that should be blocked that is passing large amounts of gas regardless of throttle setting. The bike runs strong while it runs but runs unevenly at cruise. I'm also getting some popping through the carbs at low speeds and slight throttle openings.

Been through both carbs and found them to be quite clean with no evidence of old gas residue. I have neutered the throttle shutdown enrichment circuit to no effect at all and checked the choke for function and shutoff.

Is there a gasket/o-ring/something or other that fails and allows excess gas into the engine?
Last edited by Jake on Sat Jun 29, 2019 9:05 pm, edited 1 time in total.
Reason: Threads merged

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Re: XV535 Running Super Rich

PostAuthor: Arjay » Sat Jun 29, 2019 2:55 pm

From reviewing youtube vids, some comments about the o-riing of the float needle seat has tendency to dry up and shrink, thus leaks and floods bowl and maybe cause of running rich. A carb kit with float needles is available. That and check floats arnt sinking.

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Re: XV535 Running Super Rich

PostAuthor: bstig60 » Sat Jun 29, 2019 3:33 pm

Isn't there an existing thread with this subject that you posted?
If the pilot screws being turned in all the way and it doesn't affect anything, then check the O ring that goes on the pilot screw. The other possibility is the choke leaking, but I doubt that would happen on both cylinders at the same time. The same goes for the item mentioned in post #2. Check your fuel levels using the clear tube method outlined in the service manual.
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Re: XV535 Running Super Rich

PostAuthor: Arjay » Sat Jun 29, 2019 4:13 pm

Hey Bill, just curious, does the typical carb rebuild kits include O-ring for the pilot screws.

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Re: XV535 Running Super Rich

PostAuthor: Arjay » Sat Jun 29, 2019 4:17 pm

"have neutered the throttle shutdown enrichment circuit "

how and why did you do this?

just curious.
Rj

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Re: XV535 Running Super Rich

PostAuthor: Billll » Sat Jun 29, 2019 8:43 pm

OK then. My carbs do not have adjustment screws. Everything is set and fixed except the balance and idle speed. The only O-ring I'm aware of is the one under the jet block which seems to be 7mm ID x 1.5mm thick. Rebuild kits have 2 sets of parts, gaskets and O-rings one for each model of carb that might be used. They generally include new float needles but the pictures don't show the parts in much detail or even name them.

It occurs to me that if the floats were set too high, gas could overflow into the throat and down the intake. I would love to check the float levels but this now involves removing the carbs from the bike one more time, removing the float chamber cover plates and inverting the set to see if the floats hold approximately level. The little plastic spigots one is supposed to use have been crushed shut and I've no idea how to get them out to replace them. I am tempted to remove the covers, machine vertical slots in them, and epoxy in glass windows.

I think that if the float needles were leaking, I'd be seeing gas rising to dribble out the overflow tubes with the key on and the engine stopped.

I've had all the jets out and checked them except the pilot jets which seem to be jammed into the jet block and refuse to unscrew. They are not blocked though.

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Re: XV535 Running Super Rich

PostAuthor: Billll » Sat Jun 29, 2019 9:01 pm

I started this thread by way of improving the focus of the issue. My original thread cited running on only one cylinder which was what seemed to be happening. What was happening was the rear cylinder running richer than the front one and fouling out first. Both cylinders were running very rich, just one slightly worse than the other.

I neutered the shutdown enrichment devices to eliminate them as a cause of the problem. I put a short piece of insulated wire in the vacuum port passage and set it in place with a dab of sealant. I also added a neoprene washer to the plungers to seat against the casting where the plunger went to insure stoppage of any fuel flow. It seems to have no effect so I'll remove all this next time I have the carbs off which looks like will be pretty shortly.

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Re: XV535 Running Super Rich

PostAuthor: Jake » Sat Jun 29, 2019 9:07 pm

bstig60 wrote:Isn't there an existing thread with this subject that you posted?



Now they are merged into one.
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Re: XV535 Running Super Rich

PostAuthor: Flyingdog » Sun Jun 30, 2019 1:55 am

Billll wrote: My carbs do not have adjustment screws


No adjustment screws? You mean these (pilot screws) behind the plugs? I assume you have the OEM BDS34.
535 pilot screw assembly.PNG

535 pilot screws - Copy.PNG



The other two shown (#4) are the drain screws.
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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sun Jun 30, 2019 10:31 am

The things you don't find out. My carbs have no plugs there, but yes, there are screws down at the deep dark bottoms of the holes, both seemingly set differently. I put them both at 2 turns out and will try the bike later this morning.

Front one seemed to be all the way in, rear one was 1/2 turn out.

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Sun Jun 30, 2019 9:32 pm

Pulled the pilot screws out as changing their settings didn't seem to be having much effect. I have 2 screws and 2 springs but no washers or o-rings. This could be a problem I suppose. The rebuild kits that have these in them run some $22/ea which is getting pricey (OK I'm cheap) I'll blow the passages out with parts cleaner and computer air and see if anything comes out with it then see if I can figure out what comes next. Probably buying 2 rebuild kits unless someone has dimensions for the o-ring and washer.

I believe those needles are air needles rather than fuel needles FWIW.

UPDATE: The washers and o-rings are 3mm ID and 5mm OD. I do believe I can cover this.

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Re: 1 cylinder cutting in and out

PostAuthor: Flyingdog » Mon Jul 01, 2019 10:47 am

Billll wrote:I believe those needles are air needles rather than fuel needles FWIW.


Nope..meters fuel for idle/off idle.
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Re: 1 cylinder cutting in and out

PostAuthor: Arjay » Mon Jul 01, 2019 11:34 am

Billll wrote:Arjay: I got tired of fighting the intake boots and replaced them both with 2 in PVC pipe. The ID slips over the carbs snugly, and the outside can be machined to fit snug in the backbone ports. Thus I simply slide the sleeves up completely out of the way to remove the carbs, then back down when I'm done. I suppose metal tubing would work and be less prone to breakage. Tube wall thickness is thin, I'm guessing about .020 or so.


Wow...!!! At first I thought you where joking but after thinking a bit I realized what you said was true. I would of never imagined pvc would hold up to the heat tolerances that and suffer vacuum leaks but hey learn something new every day.

I like the idea of being able to scoot the pipe inward to move out of way for remove/install. I wonder does your pipe adapt to part of existing flange (how do you bolt it to intake side of head?)

Pictures would be appreciated.

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Re: 1 cylinder cutting in and out

PostAuthor: Billll » Mon Jul 01, 2019 4:28 pm

Sorry for the fuzzy pictures. I need to find something to stabilize the camera on. You can see the PVC sleeves coming down from the air box and fitting over the tops of the carbs. At some point I'll put some clamps on them.
Intake sleeves 1.JPG
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