Need Assistance with a Carburator

[casiper]

First off, Thank you to the person that sent my a front brake house. Can't remember who did it, but I'm very grateful!

 

If you look at the pic below I put an arrow at the carb that is sticky. I need some kind of guide to get it to run. Anyone has a how to take the carbs out to clean them or any other ideas.

 

Thank you in advance

[Marcarl]

You'll have to give us some more info:

What do you mean by sticky,

Does it get fuel.

What makes you think it's not working.

[casiper]

Looking at the carbs from the top, as I was rabing the throttle, one of the carbs with that round gray center thing(sorry I'm new at this) would not slide like the other ones. I uncover the side of that carb cover and all around there was this sticky gunk. I sprayer carb cleaner as much as I could and run the engine again, but nothing changed, so that makes me think that the gunk it's everywhere.

[mbrood]

Gunk is also a very poor description.

 

Under the carb cover is a preload spring followed by the vacuum actuating bellows (known as the diaphragm) attached to the piston. The engine's changing vacuum will, on opening the throttle, allow the vacuum pulse of that cylinder to pull the piston back toward the cover... resulting in a "fluttering" of the piston, more pronouced with hogher RPM (vacuum pulses).

 

The area between the diaphragm and the piston should actually be free of any substance at all as this is controlling the air passage (via the piston in the carb throat) and also the fuel as the main needle (attached to the piston) receeds for it's seat in the carb throat.

 

You really want to get any and all "gunk" out of this area as well as the slide area the piston passes. You don't want to use any lubricant as this effects the action of the piston. Check for drag marks on both the piston body and the interior of the slide hole. There will probably be some slight marks from action over the ages but anything you can feel needs to be remedied.

 

The bellows are also very prone to pinhole leaks (primarily at or near the outer rim) and these need sealed by a very flexible sealant or replaced entirely.

 

The smooth fit of the piston and sleeve is very critical to good performance of the constant velocity style carb and the ability of the diaphragm to modulate the cylinder vacuum smoothly and accurately is the key to it all.

 

If you find "gunk" in one carb, it's demanded to check and clean the others. You want to also check the uncompressed length of each spring. A collapsed spring will only reduce performance for that carb.

[bkuhr]

Remove the 'diaphram cover' on the end of the carb.

Under it is a long spring.

Then is a black diaphram. Notice the notch/nub for alignment.

 

Reach into carb, and push with finger round gray center thing called a 'slide' to remove it and the diaphram.

 

Hold the diaphram up to light, inspect carefully for pin holes.

 

When installing align daiphram ridge into recess aligning notch/nub.

Hold slide with finger to prevent completely depressing, then install spring and cover. Sometimes the diaphram poppes out of the ridge if depressed completely prior to cover tightly secured

[casiper]

Thank you guys for the input. I will go over tomorrow morning with the info you gave me. I just learned a great deal about this.

 

Thanks again. I will post tomorrow.

[raybear71]

Inspect your slide as well as the diaphragm. My 84 had the same trouble when I assembled it this spring after it had sat for 5 years. I found a fractured slide was the problem.

[MiCarl]

First rule of carburetor service:

 

1) Keep carburetor cleaner off the rubber parts, particularly the diaphragms. It will damage the rubber, and may take some time to become apparent. I've seen 30 year old diaphragms that looked like new, and almost new ones that were degraded and shot. I'm pretty well convinced that bad diaphragms are often the result of carburetor cleaner.

 

If you've got "gunk" on the slide it's quite likely that the internals of the carburetor are also full of "gunk".

[casiper]

Well, besides the sticky stuff the diaphragm has pealed material near the rim, so I'll get a coat of flexible rubber spray tomorrow at see if I that can save me lots of money. I did also swapped that piston/diaphragm from another carb and it worked...

[bkuhr]

Well, besides the sticky stuff the diaphragm has pealed material near the rim, so I'll get a coat of flexible rubber spray tomorrow at see if I that can save me lots of money. I did also swapped that piston/diaphragm from another carb and it worked...

 

While a rubber coating can save some money for now, I have found that any coating at all adds thickness, and stiffness, DRASTICALLY effecting how the diaphrams respond. Effects are even worse when 1 diaphram is treated, and others are not. Then they start to respond at different times and throws sync way off.

 

Ya, treat them for now, but keep in back of mind if having issues, and start saving for 4 new diaphrams.

[casiper]

You are right Brian. I will start a petty cash.

 

Thanks again.

[KIC]

I just bought set of 4 diaphragms for my 87 for 86.00. When I change out my old ones ...if any of then.are good...I can send one to.you.

 

Bill

Edited May 6, 2012 by KIC

[casiper]

Thank you for offering. So as a proactive way of readiness, where could I get just the diaphragm if there's a way to just change that part only?

[KIC]

Take off side plastic and 4 carb side screws just have to be careful not to.rip them when changing.

[stevej]

Replacements are available from here: http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1794 In the past they have offered members a discount when ordering. Not real hard to change, just watch the alignment and take your time.

[casiper]

I just sent an email to siriusconinc.com regarding a single replacement. Will SD-1 work for a 1983 venture? The website only mention the XVZ1300, instead of my 1200...

[Scudrunner]

As a side question, I pulled a carb slide and diaphragm out from one of the carbs and noticed that there is a small hole at the bottom of the slide which faces the venturi area of the carb. Is that hole suppose to be positioned in relation to the diaphragm tab? I notice that I can easily rotate the slide within the diaphragm.

[timgray]

Yes you can rotate the sliders in relation to the rubber easily. I just recently changed all of mine and I could not see any holes in the diaphragms but the change was drastic on how the bike runs.

 

I strongly suggest saving your money and getting a new set of 4. My bike now runs better than it has ever ran in my ownership.

[Scudrunner]

My qusetion was about the relation of the hole in the end of the slider, not the diaphragm, in relation to the tab. The small hole in the plastic slider, can it be positioned in any direction? Thanks

[Yamamike]

Replacements are available from here: http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1794 In the past they have offered members a discount when ordering. Not real hard to change, just watch the alignment and take your time.

 

Yeah...make sure you tell them you're a VR member to get your discount.

[van avery]

My qusetion was about the relation of the hole in the end of the slider, not the diaphragm, in relation to the tab. The small hole in the plastic slider, can it be positioned in any direction? Thanks

The little hole in the bottom of the slider should be toward the motor. The tabs on the diaphragm is at about 1 o'clock and the little hole should be a 6 0'clock

[icebrrg3rd]

van avery, I just replaced my diaphragms and thought I had read somewhere / saw a pic of that hole and it's orientation. Couldn't find it again but I went with the hole towards the motor like you said. Thanks for the confirmation that I put them in the right position. All four were at random positions when I dis-assembled it. Here's hoping for a better running bike.

 

-Andrew

[van avery]

I'm still working on my 83 venture. Just does not run right below about 3200 RPM. I recieved the little rubber plugs that go into the jet holder yesterday. This will be about the 4th time into these carbs. Learn a little more each time. Good luck with yours.

[Scudrunner]

Thanks for the clarification on the hole position at 6 o'clock. I thought I read in the forums somewhere iin the past but I could not find it. Really wonder if it makes a big difference where it is positioned and for that matter, what it's purpose is.