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Vaccum issues..


Jerrod R

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4 hours ago, Marcarl said:

Keep in mind that the carbs tend to pop out of their boots on the one side as you seat the other side, and then all the clamps have to be placed properly so that they seal the boot to the carb, sometimes all that looks good but then on final inspection you might find that things are't as seated as you thought they might be. The carbs will actually make a popping sound/action when they seat properly, so if you don't get that, then keep pushing, and then check and check again.

I'll check em out.

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Made an interesting discovery.. I was looking over these rubber Tubes that run from my Head to this Black Box under my Battery, pretty confident their part of the YICS System. Anyhow,  I was looking them over and turns out several of them have holes. Does anyone have experience with these tubes, and could they be the Source of my High Idle issue?

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7 hours ago, Jerrod R said:

Made an interesting discovery.. I was looking over these rubber Tubes that run from my Head to this Black Box under my Battery, pretty confident their part of the YICS System. Anyhow,  I was looking them over and turns out several of them have holes. Does anyone have experience with these tubes, and could they be the Source of my High Idle issue?

I once had a carb mounting/induction tube split on my 1975 canam, while riding. When I came off the highway and backed off the throttle the darn bike just kept on rolling. Did not want to hit the kill button and coast around the bend at high speed so I ended using the brakes very carefully to control the bike through the turn while still allowing the rear wheel some thrust to control the bike in the turn. Still I was leaning at a very steep angle hoping the tires would not break loose.

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7 hours ago, Jerrod R said:

Made an interesting discovery.. I was looking over these rubber Tubes that run from my Head to this Black Box under my Battery, pretty confident their part of the YICS System. Anyhow,  I was looking them over and turns out several of them have holes. Does anyone have experience with these tubes, and could they be the Source of my High Idle issue?

That absolutely could be the source of your problem. You can just get rid of those hoses and cap the ports on the heads. I ran my '84 with the YICS ports capped off for years.

Edited by luvmy40
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If it's that black plastic duey then you can just remove it and cap off the intake ports that hook into it. When I did mine I then took rubber tubing and linked the ports 4 & 1 and 3&2. Don't know if it did anything but it stayed that way for I didn't notice it do any harm.

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5 hours ago, Jerrod R said:

Ok, it's still Revving but not quite as high. White Smoke is gone Plugs no Longer Fouling. Running Rich though.

Also check your enrichment valves. Make sure they are not stuck open. There is one on each carb. These are controlled by your choke lever.

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13 hours ago, Marcarl said:

If it's that black plastic duey then you can just remove it and cap off the intake ports that hook into it. When I did mine I then took rubber tubing and linked the ports 4 & 1 and 3&2. Don't know if it did anything but it stayed that way for I didn't notice it do any harm.

Would that  work like a multi carb manifold setup ?

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2 hours ago, saddlebum said:

Also check your enrichment valves. Make sure they are not stuck open. There is one on each carb. These are controlled by your choke lever.

Nope no issues, I've never been so let down to find that all my Engine Component's are functioning as they should lol.

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If memory serves me right: false air will cause a lean issue and because of the mixture going into the combustion chambers is too lean not all the fuel will burn and so some will be exhausted out the tail pipe causing a smell of unburnt fuel, making one think that there is too much fuel. 

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1 hour ago, Marcarl said:

If memory serves me right: false air will cause a lean issue and because of the mixture going into the combustion chambers is too lean not all the fuel will burn and so some will be exhausted out the tail pipe causing a smell of unburnt fuel, making one think that there is too much fuel. 

Normally that only happens if the fuel mixture is so lean that the cylinder will not fire at all the plugs come out wet but clean and is very rare. In most cases a too lean a mixture causes valves to burn and the plugs will be very white.

 

6 hours ago, Jerrod R said:

Welp at least Today wasn't a total loss, It seems to be done Fouling Plugs. Might order a set of those Gauges and see if the Carbs are out of Wack. I don't think that's it, but I'm running out of things to check..

No the feeling. Run into it all the time when customers come in with complaints sometimes more than once and we can't find a single thing wrong.

Best one was a customer who claimed his starter was faulty and sometimes the truck would not start usually when he shut down at a border crossing. we went through that truck with a fine tooth comb and found nothing. He had the starter replace in the states 4 times finally he said don't diagnose it just replace everthing, Ign switch, relays, all four batteries and get a new starter not a rebuilt. We even ran a ground from the battaries directly to the starter. He still had the problem. He got so fed up he dealt the truck on a brand new one. On his third border crossing the brand new truck refused to start. You can only imagine his frustration.:bang head:  

I actually gave serious thought to gifting the guy with a couple gremlin bells. Then covid happened and my doctor due to my medical history (pneumonia 3 times in a 40 year span for one) called me told me to stop going to work.

Edited by saddlebum
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  • 2 weeks later...
On 1/13/2022 at 9:10 AM, saddlebum said:

Normally that only happens if the fuel mixture is so lean that the cylinder will not fire at all the plugs come out wet but clean and is very rare. In most cases a too lean a mixture causes valves to burn and the plugs will be very white.

 

No the feeling. Run into it all the time when customers come in with complaints sometimes more than once and we can't find a single thing wrong.

Best one was a customer who claimed his starter was faulty and sometimes the truck would not start usually when he shut down at a border crossing. we went through that truck with a fine tooth comb and found nothing. He had the starter replace in the states 4 times finally he said don't diagnose it just replace everthing, Ign switch, relays, all four batteries and get a new starter not a rebuilt. We even ran a ground from the battaries directly to the starter. He still had the problem. He got so fed up he dealt the truck on a brand new one. On his third border crossing the brand new truck refused to start. You can only imagine his frustration.:bang head:  

I actually gave serious thought to gifting the guy with a couple gremlin bells. Then covid happened and my doctor due to my medical history (pneumonia 3 times in a 40 year span for one) called me told me to stop going to work.

Lol, I definitely Can. When Covid first Hit and I got basically laid off I started going Crazy try to adapt to not working 50 Hours a Week. So I found worn out 74 CB-750 and bought it for 300 bucks. Now I'm kinda addicted to putting Old Bikes back on the Road. I did an 82 XJ-750 Maxim Cafe Racer last year and went through Hell getting the Mack 4 into 1 and Pod's to work right. Now this Venture is giving me all sorts of Problem's..

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Alright lol, I think I need some time away from this thing.. It is now refusing to start, it won't even sputter. I have brand new Plugs that have a solid Blue spark, new Air Filter, and Pilot Screws are set to Factory Spec, and it's getting fuel. It's almost like when I tighten the Plugs down they stop sparking. I think I need to take a step back from it...

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Had a friend who bought custom air filters for a 1982 Virago 750 , and it ran terrible after ...He asked for help , and I did mention that his fuel / mixture was off ...He said that I had to prove it ...I wrapped electrical tape around half the  air filter screen and the engine went to a  perfect idle and ran great . 

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First start of the spring, my 83 was very temperamental to start. I found that a charged battery, remove the air filter cover, a squirt of starting fluid in each carb (aka ether), boom it always started.  I would quickly add the air box lid and snug the bolts. I also never choked it until after it was started, and never twisted on the throttle until after it was started.

Edited by SpencerPJ
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5 hours ago, Jerrod R said:

Alright lol, I think I need some time away from this thing.. It is now refusing to start, it won't even sputter. I have brand new Plugs that have a solid Blue spark, new Air Filter, and Pilot Screws are set to Factory Spec, and it's getting fuel. It's almost like when I tighten the Plugs down they stop sparking. I think I need to take a step back from it...

Take off the air box, squirt some carb cleaner or brake clean into each cylinder and then turn it over. If it fires then you know you have spark and your issue is fuel related. If it doesn't fire then check out why it doesn't spark.

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1 hour ago, Marcarl said:

Take off the air box, squirt some carb cleaner or brake clean into each cylinder and then turn it over. If it fires then you know you have spark and your issue is fuel related. If it doesn't fire then check out why it doesn't spark.

Or grab a beer and come back to it another day :beer:

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8 hours ago, SpencerPJ said:

First start of the spring, my 83 was very temperamental to start. I found that a charged battery, remove the air filter cover, a squirt of starting fluid in each carb (aka ether), boom it always started.  I would quickly add the air box lid and snug the bolts. I also never choked it until after it was started, and never twisted on the throttle until after it was started.

Yes lol, I broke down and bought some starting fluid today and she fired off. But still doing the same thing.. Idles super High with the Airbox Cap on, Comes down some with just the filter and actually kinda runs ok with just the Velocity Stack's. But it's doing small Backfire's the whole time, and I know it has to be Lean..

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Just now, Jerrod R said:

Yes lol, I broke down and bought some starting fluid today and she fired off. But still doing the same thing.. Idles super High with the Airbox Cap on, Comes down some with just the filter and actually kinda runs ok with just the Velocity Stack's. But it's doing small Backfire's the whole time, and I know it has to be Lean..

It has something to do with Vaccum, as soon as the Cap Sucks down it Revs up. I feel like it has something to do with the Cruise Control but I disconnected it a Month ago and no change.

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Just now, Jerrod R said:

It has something to do with Vaccum, as soon as the Cap Sucks down it Revs up. I feel like it has something to do with the Cruise Control but I disconnected it a Month ago and no change.

Well, I'm also pretty sure the Cruise Control opens the Butterfly's, and their not moving when it Revs.. It's running better since I Synced and Adjusted the Carbs. But something that uses Vaccum to Rev the Motor if not functioning the way it should.

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It's idling at 2500 RPM without the Cap or Filter, with just Filter 4000 then with the Cap on it jumps to 5500 RPM instantly. And I shut er down. What it feels like is the more I Restrict what it can draw through the Intake, the more it's drawing through a Leak somewhere under the Carbs. Only Problem with this theory is the Plugs aren't suggesting a lean mixture. Their just Black, which in my admittedly uneducated Brain is suggesting slightly Rich. 

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Seems to me you have extra air coming in from somewhere. It seems again that with the air box off it's easier for the air to travel through the carbs rather than from the other direction, and once you install the air filter etc then the other source becomes easier. If it were here in my shop I would be taking a real close look at how the carbs are seated and if the clamps are seated properly all the way around and tight. At the bottom of the carbs there is what would insert into the boots and right above that is a flange. That flange needs to be flat against the boots and I would check all 4 carbs to make sure they are in proper position.

It's hard to trouble shoot from a distance, darned hard.

Could you take some pictures from both sides and post them?

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