Vmax running on 3 (or 2??) cylinders

[Joe Planter]

How did you "resolve" the issue with the carburetors? During one of those countless disassembly sequences, did you take the jet block apart and pull the pilot jets out of all four? And confirm you cleared them?

The reason I ask is because it sounds like you have an issue with your carburetors.

Well that’s the thing, I did have an issue with my old carbs. I pounded all the brass pieces out that the float valves sit in, thus widening the hole and the little filter brass piece not fitting and moving up and down as the bike was running. The mechanic I took it to took the time to show me where I went wrong and told me that if I got a new (used) set of carbs and was very careful and did the steps that he told me that the bike would be good as new. Well unfortunately that wasn’t the case. I bought a used set of carbs, inspected them before even cleaning them to make sure I wasn’t getting a bad set of carbs. Everything seemed to be in order with them other than the fact that they were pretty dirty. But this wasn’t really a problem, I took about 6 hours fully taking everything apart on them and thoroughly cleaning them, and replacing bad parts on them as needed. Threw them on the bike, it started and it actually seemed to be running on 4 cylinders, sounded really good, no popping, I had never heard it sound like this. Well there was a leak in one of the float bowls, so I took carbs off again, fixed the leak, put back on, and here we are again with the issues.

 

[Joe Planter]

View attachment 72189 View attachment 72190

Pilot jet, clean and cleared.

I don't recall you saying that you suspected an air leak, but spraying your entire set of carbs, from the air boots to the VBoost to cyl head point, to see if your rpm's rise, indicating an air leak, is what I think you should try. You use starting fluid. Some people use propane, but a liquid is easier to see where it goes, compared to a gas (not 'gasoline' but one of the states of matter: solid, liquid, gas). Remember that you may-locate one leak, but you have-to keep going because there may-be another, or even-more than that. I had an idle difficulty on a bike I was working on recently, and the air leak was the o-ring between the VBoost manifold and the cyl head on the #2 cyl. My suggestion is, if you find a result like that, you replace all four of the o-rings! Why have-to re-do all your work, because in the disassembly, one of the fragile o-rings also became incapable of making a good seal? Replace all-four.

Are you referring to the rubber intake boots that the carbs fit into? If so mine were super cracked and terrible before, so I ordered some new ones and threw them on just to be sure I had no leaks there.

 

[Joe Planter]

Also I thought this might be worth mentioning. My bike is a California model with the canister, the carbs I ordered are from a non-California model, so the hose from the canister has nowhere to go. Could this be an issue?

 

[Joe Planter]

How did you "resolve" the issue with the carburetors? During one of those countless disassembly sequences, did you take the jet block apart and pull the pilot jets out of all four? And confirm you cleared them?

The reason I ask is because it sounds like you have an issue with your carburetors.

Which part is the jet block? Is that the part that is inside the float bowls?

 

[desert_max]

View attachment 72189 View attachment 72190

Pilot jet, clean and cleared.

I don't recall you saying that you suspected an air leak, but spraying your entire set of carbs, from the air boots to the VBoost to cyl head point, to see if your rpm's rise, indicating an air leak, is what I think you should try. You use starting fluid. Some people use propane, but a liquid is easier to see where it goes, compared to a gas (not 'gasoline' but one of the states of matter: solid, liquid, gas). Remember that you may-locate one leak, but you have-to keep going because there may-be another, or even-more than that. I had an idle difficulty on a bike I was working on recently, and the air leak was the o-ring between the VBoost manifold and the cyl head on the #2 cyl. My suggestion is, if you find a result like that, you replace all four of the o-rings! Why have-to re-do all your work, because in the disassembly, one of the fragile o-rings also became incapable of making a good seal? Replace all-four.

Well now regarding an air leak, if the carbs have been on and off several times, it is possible to get them crossed up and cock-eyed or not fully seated when you reinstall them. If that were the case, you could have an air leak. Could be a bad one. But I would expect it to idle very high as a primary symptom of that, but if it's bad enough, who knows how it's gonna run.

 

[Joe Planter]

Well now regarding an air leak, if the carbs have been on and off several times, it is possible to get them crossed up and cock-eyed or not fully seated when you reinstall them. If that were the case, you could have an air leak. Could be a bad one. But I would expect it to idle very high as a primary symptom of that, but if it's bad enough, who knows how it's gonna run.

Yes, this happened one time when I put the carbs on, but then I ended up rearranging them and getting them seated properly. I will try and get starting fluid and spray at different point to check for leaks as well. Also do you guys know of anyone near my area (San Francisco/Alameda/San Jose area) from the forums that may be able to help me out?

 

[desert_max]

Here’s a shot of my carbs disassembled sometime back. You can see a Jet block removed and jets out of one. The pilot jet and the one that’s critical is the smaller one.

 

[Joe Planter]

Here’s a shot of my carbs disassembled sometime back. You can see a Jet block removed and jets out of one. The pilot jet and the one that’s critical is the smaller one.View attachment 72192

Oh okay then yes, I have taken these off many times to be sure they are clean, even took the jets out of them and cleaned those thoroughly. I did use some grease to seal the float bowls, is it possible that some grease maybe got into the carbs and clogged something up? I don’t know, thinking of all possibilities at this point.

 

[desert_max]

Well, you could definitely be onto something there about carbs being contaminated. But, I haven't seen you mention anything about the condition of the inside of the fuel tank. If it's full of rust, the cleanest carburetors in the world probably won't stay clean for very long. Your carbs live downstream from a sewage plant. Minute particles can get through the filter. Inspect the inside of the tank carefully with a bright light, and either confirm or replace that you have a clean fuel filter.

 

[Joe Planter]

Well, you could definitely be onto something there about carbs being contaminated. But, I haven't seen you mention anything about the condition of the inside of the fuel tank. If it's full of rust, the cleanest carburetors in the world probably won't stay clean for very long. Your carbs live downstream from a sewage plant. Minute particles can get through the filter. Inspect the inside of the tank carefully with a bright light, and either confirm or replace that you have a clean fuel filter.

Okay, what am I looking for when I check the tank, because I’ve looked inside it before and haven’t seen anything out of the ordinary. Do I need to drain the gas out and check it that way? Also when I checked the fuel filter that looked clean as well. Fuel pump issue maybe as well?

 

[desert_max]

Rust = bad.
Shiny metal = good

No need to drain if it's half full or so. Also, unless your filter is clear plastic, you cannot confirm it's clean. Just replace it. Cheap enough.

 

[Fire-medic]

Rust = bad.
Shiny metal = good

No need to drain if it's half full or so. Also, unless your filter is clear plastic, you cannot confirm it's clean. Just replace it. Cheap enough.

A good small flashlight should provide sufficient illumination to verify the condition of your tank innards. Anything but shiny metal is bad. It's not much of a deal to remove the gas tank, if you have-to, if you discover it has issues. There's a thread on it.

Take your fuel filter to the auto parts store, and you should be able to find a replacement which fits the available space, for about $5-$6. If you do a search on-here, you can get the NAPA or other part #. The Russell metal filter is a good one, as it's cleanable/re-usable. I open my gas filters to see what it caught, once the new one is aboard. Like the ancient priests examining the owl entrails, for foretelling the future, it's helpful in diagnosing issues. If you find rust-dust, or actual rust particles, you know what to expect when you examine the gas tank.

 

[Joe Planter]

A good small flashlight should provide sufficient illumination to verify the condition of your tank innards. Anything but shiny metal is bad. It's not much of a deal to remove the gas tank, if you have-to, if you discover it has issues. There's a thread on it.

Take your fuel filter to the auto parts store, and you should be able to find a replacement which fits the available space, for about $5-$6. If you do a search on-here, you can get the NAPA or other part #. The Russell metal filter is a good one, as it's cleanable/re-usable. I open my gas filters to see what it caught, once the new one is aboard. Like the ancient priests examining the owl entrails, for foretelling the future, it's helpful in diagnosing issues. If you find rust-dust, or actual rust particles, you know what to expect when you examine the gas tank.

Thank you, also where is the CDI box located. I want to try and take that apart and see if there’s anything out of the ordinary going on in there

 

[Joe Planter]

A good small flashlight should provide sufficient illumination to verify the condition of your tank innards. Anything but shiny metal is bad. It's not much of a deal to remove the gas tank, if you have-to, if you discover it has issues. There's a thread on it.

Take your fuel filter to the auto parts store, and you should be able to find a replacement which fits the available space, for about $5-$6. If you do a search on-here, you can get the NAPA or other part #. The Russell metal filter is a good one, as it's cleanable/re-usable. I open my gas filters to see what it caught, once the new one is aboard. Like the ancient priests examining the owl entrails, for foretelling the future, it's helpful in diagnosing issues. If you find rust-dust, or actual rust particles, you know what to expect when you examine the gas tank.

Also thought I might mention this. When I was taking off the throttle cables I noticed that somebody had wired in a switch. It looks like it went all the back to where the battery is located, but the connection had slipped out under the tape that was holding it connected. I’m not sure if this could be something, but was reading another forum and someone said something similar. May try reconnecting that and flipping the switch to see what happens

 

[one2dmax]

I would NOT use grease on any carb part. The seals may not like it which can distort any of the orings and other parts inside the carbs. AND, sealant or grease on orings can actually cause the oring to displace and lose it's seal. In short, install dry and if the orings are in question then you need to replace them.

It does sound like a typical carb issue with the pilots. Float settings are VERY critical as well so make sure you are paying attention to that.

If it's got spark on any cylinder then the pickup is working. You could have issues with something electrical too. We can always loan out some parts to swap around and check with.

 

[Joe Planter]

I would NOT use grease on any carb part. The seals may not like it which can distort any of the orings and other parts inside the carbs. AND, sealant or grease on orings can actually cause the oring to displace and lose it's seal. In short, install dry and if the orings are in question then you need to replace them.

It does sound like a typical carb issue with the pilots. Float settings are VERY critical as well so make sure you are paying attention to that.

If it's got spark on any cylinder then the pickup is working. You could have issues with something electrical too. We can always loan out some parts to swap around and check with.

Thank you Sean for the reply, I’ve heard about float setting but don’t know what they are. Can you explain?

 

[one2dmax]

See dry method picture attached

 

[Fire-medic]

CDI box is behind the steering head. It's in a rubber sleeve.

 

[Joe Planter]

So does anyone know what this switch might be for or be to? I uploaded some pictures.

 

[Fire-medic]

The round, white plug w/the black band is the VBoost motor. Does that 'hockey-puck' plug into that somewhere? Is the switch a 2 pole, so it has two positions? Trace the wires from the hockey puck and tell us where they run to, what the wire colors are that it goes to. I suspect it's some-sort of VBoost selectable controller.

Do any of those wires go to your schmancy high-tension spark plug wires/caps?