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Weak fuel pump?


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Glad to see things are coming together! 

Regarding mpgs, the best for economy comes when you let the motor run. IE,  don't bog her down at lower rpms. Especially riding 2 up. Staying in a lower gear, running 3k to 4k rpm, will give you better mpgs than shifting up. Seriously. Experiment. 

Change oil regularly, change plugs yearly and let her run!

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Thanks for all the suggestions. I did run the tank down and filled up with fresh gas. I'm sure there is a little B12 still left but I can't imagine it would be enough to damage anything. I will be taking it out again this weekend for a ride. I have been really driving the heck out of it since it is back to running in prime shape. Fuel economy is definitely up, was over 110 miles on that tank when it went down to 1 bar when the best I could get before was around 90-95 miles before it went down to one bar consistently. 

I am still curious to how this fuel additive solved the problem. I had two theories, but not sure and I guess I will never know without taking the carbs apart again to find. With it running OK I am not touching it at this point. One, is that the B12 caused the desiccated rubber plugs to swell and seal as needed, the other is that I obviously missed some fuel passage or didn't get an emulsion tube cleaned out properly. I looked around with a google search but haven't seen anyone confirm that B12 causes rubber to swell, other than a couple of posts where people theorized that it did. I probably wouldn't have thought twice about it, but after having the carbs off and tinkering with it twice, I am intrigued. 

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1 hour ago, TTrax said:

I am still curious to how this fuel additive solved the problem

 

A big part of it is the gunge that builds up in the carbs. A substance that separates from standing gas as the vaporous components of the gas slowly evaporate  and mix with moisture from condensation forming a jell like substance that over time crystalizes. The B12 or similar products dissolves this gunge and it then gets flushed out as fresh gas passes through the carb.  

I assume but could be wrong but this gunge may be a crude form of paraffin, a real common issue with diesels and is why you often hear of summer fuel and winter fuel were big rigs are concerned. In winter this stuff can jell in a heartbeat and bung up the entire fuel system in sub freezing temperature.

Edited by saddlebum
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Paraffin was the #1 cause of a truck motor top end failure for me. At the time, years ago, I was using a well known oil. It seems it had some sort of a wax base? That's the gist of the report back from lab. It accumulated in the top end, clogging up everything!

So, that type of crud coming from today's gas mix, adding moisture to it, doesn't surprise me at all. I've seen old gas in a plastic fuel tank look like golden wax. For that to dissolve and cause issues...makes sense! 

I would have to surmise, T, that the B12 did it's thing and cleaned up the crud. By riding the scoot like you stole it... Helped as well. These motors love to run!

The next time you go back into the carbs, adjust the float bowls to a lower level. (For some reason, that leans out the carbs resulting in better economy). Then, reset your pilot jets to 2.5 turns out. That should be close for the air/fuel mixture of the pilot. If you have an exhaust gas analyzer you can nail each carb perfectly. That will help as well since the pilot jet is active a good party of the running rpm. 

Those 2 things will up you're mpgs to the high 30s. Usually we get around 38 to 40mpgs... on average. But as I mentioned earlier, keeping the motor in the 3k to 4k rpm range when cruising helps the most. Staying out of 5th gear until 70mph is important. Example: 2 up with a headwind...I would be in 4th gear around 65 to 70mph all day long. Above 80moh, mpgs dump hard! 

 

 

jet-chart.jpg

Edited by videoarizona
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Well, something strange is going on for sure.

Over lunch break today, I took it back out with the fresh tank of gas and now it is back to surging. Not as bad as the other day but it is back. I took it for a 35 mile ride and tried to give it hell a few times but it didn't seem to improve. I stopped at the gas station and went ahead and dumped the rest of my half can of B12 in the tank and took it up on the highway to get the fuel from the tank to get into the fuel bowls for sure. It seemed to be back to revving out 100 percent with only a hint of possible surge. It is a little windy today so that might have had an effect too.

It seems to me that either the B12 is causing the seals to swell in the carbs, or changing the combustibility of the fuel so it is easier to light off. I have a tendency to believe it is affecting the rubber parts in the carbs as previously when I first used the additive, the bike went from having a complete bog-out at 5K rpm to revving out to 7K (albeit surging while getting there). Then the bike sat in the garage for 2 weeks and when I took it out again, the surging was completely gone. This was all on the same tank of fuel (between the surging and the perfect running).

I went ahead and ordered the rubber plugs and bowl gaskets from SCI just a few minutes ago, hoping this will be what resolves the issue totally. If not I might be circling back around to having someone rebuild the carbs. I am disappointed but also relieved that I seem to be at least finding something that makes a difference to how the bike runs after taking the carbs out twice already.

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Noting a change whether good or bad but appearing to be isolated to a certain part or area of the bike is always a good thing.  Now at least you have some idea were to concentrate your efforts in rooting out the negative issues. One thing I did not mention and should have is the fact that depending on how long any moisture may have sat in the fuel bowl you may also have some corrosion (yes contrary to what some believe aluminum does corrode ) bits can fake off and clog orifices etc.

I have a friend with a Harley that cuts out in the rain on him but every time he comes to me to check out the issue the bike is on its best behavior even when I try spot spraying the suspect areas or hosing it down completely and repeating the process in the dark to try and spot any electrical arching, Its like its deliberately trying to make a liar out of him. In the end I just pulled apart his entire  electrical system, primary and secondary plus charging system cleaned and dielectric greased everything. Now we just sit back and wait for his next ride in the rain.

Edited by saddlebum
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  • 2 weeks later...

Well, I think I have all the parts that I need to try to internally reseal these carbs. I already had the gasket between the jet block and carb body with the car kits I had gotten from SCI, and recently have ordered the jet block plugs from them as well. I did also buy new o-rings that are installed on the emulsion tubes (which wasn't cheap) but figured I better cover that base as well. 

Another possibility that I just thought of that has me worried is possible internal damage to the carb. We had the super cold snap this last February and we got down to -17°F here. Really hoping there wasn't any water in any of the carbs that caused a crack if it froze. I might just be getting myself worked up but am thinking that this is possible.

I am thinking I will probably be working on this in October at the earliest. For some reason, it runs perfect with some B12 Chemtool in the tank. I definitely don't want to do this long term as I am sure it will have a detrimental effect on the fuel system components eventually. For now, it has been fine though. I have been running it around the recommended dosage in every other tank. We have a ride to Eureka Springs planned for labor day weekend so hopefully all will be well to at least that trip is over.

Once again, thanks for all the suggestions. Once I get the new rubber in the carbs I will let you know if it seemed to fix it or not. Have a good weekend!

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  • 3 weeks later...

OK back from the trip. I had been hoping all would be peachy as the bike had been running flawlessly the last few weeks but should have known my luck was running out.

We got to about Afton, OK when we ran into a storm front and pretty much had to run with the rain all the way to Eureka Springs. We didn't have any engine/carb related issues that whole trip down on Saturday. 

The next day all seemed to be going well, we ran up to Branson, MO and then back down to Eureka Springs. On the way down, we fueled up and went on our way. Later that evening I noticed some hesitation at low RPM. When I twisted the throttle harder, I heard some popping coming back through the air filter location, so I am assuming it was a lean backfire. When we got out on a straight road, I ran it through the gears up to around 6500 RPM and afterwards it seemed to run much better.

The next day as we were heading out to come back, I noticed it was running poorly again at lower speeds. The more I drove and the warmer it got, it seemed to get much worse. At RPMs below 3K it would pop and backfire through the carbs. When running at 70 MPH it ran perfect from what I could tell. At lower engine speeds, it would surge and backfire. When I finally got back to the interstate on the last few miles on the way home, it would surge at around 80 MPH.

I am thinking I got something into a pilot jet of one of the carbs, or I have a vacuum leak at a carb boot that can't be seen. I do have some small micro cracks on the boots, but they have been that way for a few years. When I got home and the bike was still running rough at idle, I sprayed some carb cleaner on the boots to see if the engine speed would change, but there was no change. I had also checked the carb boots on the top of the carbs to make sure they hadn't come off but they were fine. I tried to tighten the lower boots in case air was being drawn in there but they were all tight.

I am thinking I got some bad gas at the gas station since we had just come through some heavy rains and I know a lot of times water can get into underground tanks when this happens. I was pretty sure something was wrong with a pilot jet, but doesn't explain why it also starts surging at higher speeds as well. I guess it doesn't matter since I knew the carbs were going to have to come off anyways. This will definitely accelerate my plans on working on it instead of waiting until later. I still need to check to see if my fuel supply is adequate from the pump as well.

I just thought I would state what happened on the way down and if anyone agrees or has another idea what might be happening with the backfire. I did order the lower carb boots last night so they will be getting replaced when the carbs come off. For some reason, the ebay listing I had ordered from stated the carb boots were for the 83-86, and then 89-93 models. I didn't see that the part numbers of the boots changed for 87-88 but let me know if there was a change that I missed. At least on the parts pictures I seen from the Ventures from the 90's were the same as the 88 model so I went ahead and ordered them. 

Hope everyone had a good holiday weekend!

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7 minutes ago, BlueSky said:

Check the spark plug wires at the caps for green copper wire.  

I had converted over to the COP's from Ignitech, would you see backfiring through the carbs if the coils weren't firing? I had always thought backfiring through the intake was due to a lean fuel mixture. I will go out and check to make sure water hasn't gotten into the connectors. They are weather pack connectors at the coil but the connectors between the bike wiring harness and the adapter harness to the COPs aren't weather proof.

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The connectors at the ignition module are not weather sealed and if there is any green fretting in those connectors any moisture getting in and mixing with that green fretting material will wreak havoc with you ignition as it creates a path for electrical crossover. You also have a strong argument for water in the fuel as you stated it is not uncommon for fuel stations to get water in their holding tanks after a heavy rain and your timing certainly suggests  strong possibility of getting bad fuel. Back fire can also be the result of unburnt fuel from a misfiring cylinder being ignited in the exhaust system by the hot exhaust stream of a firing cylinder.

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On 9/7/2021 at 9:10 PM, saddlebum said:

The connectors at the ignition module are not weather sealed and if there is any green fretting in those connectors any moisture getting in and mixing with that green fretting material will wreak havoc with you ignition as it creates a path for electrical crossover. You also have a strong argument for water in the fuel as you stated it is not uncommon for fuel stations to get water in their holding tanks after a heavy rain and your timing certainly suggests  strong possibility of getting bad fuel. Back fire can also be the result of unburnt fuel from a misfiring cylinder being ignited in the exhaust system by the hot exhaust stream of a firing cylinder.

I did check the connectors at the ignition module this evening and they are bright and shiny with no evident corrosion.

I did run the bike with the top of the air cleaner off and filter element removed. I ran the bike until it was up to operating temperature and the idle became uneven. I sprayed some carb cleaned down the throat of each carb a little at a time. On cylinders 2,3, and 4 the engine would slow down. When I sprayed it down the throat of the carb on cylinder 1, the engine would stabilize on idle. Same with running the engine at about 2500 RPM, sprayed some carb cleaned down cylinder 1 and it seemed to smooth out. I drained the fuel out of that bowl and didn't see anything floating around, although I am sure all it takes is a speck of something to partially block the pilot jet. Not a dead miss but definitely not hitting most of the time. 

Hopefully I will get a chance to get the carbs off this weekend. I had ordered the lower carb boots but found they are coming out of Germany via Deutsche Post so it might take some time to get here. I'm half tempted to just run with the boots I have to salvage a few more days of riding if possible but probably would be wise to wait for the new boots or I will be taking the carbs off again someday in the future. Starting to get to be a pro at it, seems like I can have them out in under an hour anymore.

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My smelly opinion, warning!  Ha!  B12 has acetone in it as one if its ingreadients.  Acetone is known as a universal solvent meaning it will dissolve almost anything. Sooo, I'm afraid to use it.  

I use seafoam and mostly use Gumout for high mileage engines with PEA, polyetheramine, the latest and greatest fuel injector cleaner.  I use Gumout in all of my gasoline powered devices, cars, truck, motorcycles, weedwhacker, blower, mower, boat motor.  I've notice improvements in everything I've used it in, especially the boat motor, motorcycles, and lawn tools that don't get used a lot.  Repeat!  My smelly opinion!  

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1 hour ago, BlueSky said:

My smelly opinion, warning!  Ha!  B12 has acetone in it as one if its ingreadients.  Acetone is known as a universal solvent meaning it will dissolve almost anything. Sooo, I'm afraid to use it.  

I use seafoam and mostly use Gumout for high mileage engines with PEA, polyetheramine, the latest and greatest fuel injector cleaner.  I use Gumout in all of my gasoline powered devices, cars, truck, motorcycles, weedwhacker, blower, mower, boat motor.  I've notice improvements in everything I've used it in, especially the boat motor, motorcycles, and lawn tools that don't get used a lot.  Repeat!  My smelly opinion!  

I agree, I knew that it isn't ideal to use this stuff long term. Was hoping it would hold out the rest of the riding season but wouldn't be surprised to find some granulated rubber or debris getting into the jets. I have a new fuel filter between the tank and the fuel pump / carbs so I think if there was any debris it would have to originated there. I will be taking the carbs off soon to see what I can find, especially on carb #1.

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Today was spent working on the bike. I got the carbs out and started with the one I thought was causing the problem, carb on #1 cylinder. I checked the pilot jet and I could see light through it but it was dim. After spraying carb cleaner and compressed air, it seemed a light brighter when checked again. I went ahead and replaced all rubber components with what I had on hand. This included the o-ring around the jet tube and the gasket between the jet block and carb body. I also replaced the rubber plugs at the bottom of the jet block.

I can confirm for sure that B12 chemtool will swell old rubber to some degree. The original rubber plugs were sealing well. I won't say they were the most supple rubber I have ever seen but they would seal against the bore of the block whereas originally they were like chalk pieces and would fall right out. I didn't trust that they wouldn't start disintegrating so they were slated for replacement. 

After I replaced the rubber components I went ahead and blew everything out with compressed air and carb cleaner (on all four carbs). After I put it all back together, I ran a carb sync and when the bike had warmed up, the rough running and missing was gone. I finished putting it back together and took it for a test drive and confirmed, at least for now, everything is working as intended (God willing it will be okay in the future for awhile as well!) No backfiring through the carb at low loads and would blast to high speeds on the interstate easily. I ran the tank with the remaining B12 down to 2 bars on the gauge and refilled with fresh gasoline with no additives. I know there is still some B12 in there but should be diluted and plan on taking a longer ride tomorrow and run several tanks of clean gas through it. 

I still can't confirm what was blocking the pilot jet, it wasn't totally blocked off which could also be confirmed that the bike didn't have a dead miss and I could see light from it. Frankly, it scares the hell out of me since I had a new filter installed when I did the new fuel pump. I can only imagine that the contamination originated somewhere between the filter and the pilot jet. I'm not sure if bad gas can pass contaminants past a filter that can coalesce into a jet and restrict it. It is also possible some varnish that cut loose off the carb bowl or some other contamination from a fuel line got in there. Really hoping I don't have to do this again for awhile but getting to where I can get it done in a day at a leisurely pace. 

I will update further if I have other problems, but praying this baby has been put to bed. Thanks for all the help and suggestions, have a great weekend! 

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11 hours ago, TTrax said:

Today was spent working on the bike. I got the carbs out and started with the one I thought was causing the problem, carb on #1 cylinder. I checked the pilot jet and I could see light through it but it was dim. After spraying carb cleaner and compressed air, it seemed a light brighter when checked again. I went ahead and replaced all rubber components with what I had on hand. This included the o-ring around the jet tube and the gasket between the jet block and carb body. I also replaced the rubber plugs at the bottom of the jet block.

I can confirm for sure that B12 chemtool will swell old rubber to some degree. The original rubber plugs were sealing well. I won't say they were the most supple rubber I have ever seen but they would seal against the bore of the block whereas originally they were like chalk pieces and would fall right out. I didn't trust that they wouldn't start disintegrating so they were slated for replacement. 

After I replaced the rubber components I went ahead and blew everything out with compressed air and carb cleaner (on all four carbs). After I put it all back together, I ran a carb sync and when the bike had warmed up, the rough running and missing was gone. I finished putting it back together and took it for a test drive and confirmed, at least for now, everything is working as intended (God willing it will be okay in the future for awhile as well!) No backfiring through the carb at low loads and would blast to high speeds on the interstate easily. I ran the tank with the remaining B12 down to 2 bars on the gauge and refilled with fresh gasoline with no additives. I know there is still some B12 in there but should be diluted and plan on taking a longer ride tomorrow and run several tanks of clean gas through it. 

I still can't confirm what was blocking the pilot jet, it wasn't totally blocked off which could also be confirmed that the bike didn't have a dead miss and I could see light from it. Frankly, it scares the hell out of me since I had a new filter installed when I did the new fuel pump. I can only imagine that the contamination originated somewhere between the filter and the pilot jet. I'm not sure if bad gas can pass contaminants past a filter that can coalesce into a jet and restrict it. It is also possible some varnish that cut loose off the carb bowl or some other contamination from a fuel line got in there. Really hoping I don't have to do this again for awhile but getting to where I can get it done in a day at a leisurely pace. 

I will update further if I have other problems, but praying this baby has been put to bed. Thanks for all the help and suggestions, have a great weekend! 

Some of us think that the fuel lines tend to break down on the inside due to ageing and ethanol, you might think about changing those out.

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19 minutes ago, Marcarl said:

Some of us think that the fuel lines tend to break down on the inside due to ageing and ethanol, you might think about changing those out.

Thanks, all fuel lines have been replaced with new ones a couple months ago. I am hoping that won't be an issue for awhile. I might make replacing them part of normal maintenance in the future with what you mentioned in mind.

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  • 1 month later...

Well, I hate to say it but this issue is still ongoing. 

The original issue with the cut out at 5K RPM has been resolved but somewhere along the way I made myself some more problems.

The last time I had mentioned having issues was on the trip back from Arkansas. I did take the carbs apart and cleaned the jets. All seemed well for awhile but then the problem came back, almost the same. Engine would surge at highway speeds. By the next day, you would have much popping and backfiring through the carbs at lower speeds. I once again took the carbs apart to clean them, blowing back through the jets and also through the needle valve seat with carb cleaner and compressed air.  I also replaced the fuel lines and fuel filters. Instead of only running one filter at the inlet of the fuel pump, I installed another one right at the carb in case junk was shedding off the pump and getting into the carbs. 

I had high hopes of getting it resolved but I can't seem to avoid the same thing from happening. I estimate in about 200-500 miles the same thing happens again. I think I have had the carbs off 4 times now with this same issue. There is definitely something to be said for completely rebuilding something instead of trying to hone in on one part of the carburetor.

At this point I have to think there is some material shedding somewhere internally in the carbs. I have replaced the rubber plugs in the jet block and the gaskets between the jet block and carb body. I am trying to think of some other areas that might be contributing debris. One I can think of is the floats themselves. I didn't notice that they were flaking off but wonder if they could be causing problems. I'm sure this is all self inflicted as I had left B12 Chemtool additive in the tank for about 2 months time. The other possible place might be in the enrichment circuit. I'm not sure how it is integrated with the rest of the carb. Does it work with the pilot jet for fuel or is it stand alone and gets its fuel from a different supply?

I have started to honestly consider going to a single carb conversion. I had seen a couple of options on Ebay, one used a double barrel Webber carb and the other used a carb off a VW 1600cc engine. At this point I would jump on it but not sure how much fabrication would be involved, such as having to install a new throttle cable set up to run the carb. If anyone has experience with one of these, I would love to hear some specifics on the installation and additional fabrication that has to be done. 

If anyone has had a similar experience with the factory carbs and seeming to plug themselves up, I would also like to hear of what was found or if there is a common source that might be causing issues with the carbs being plugged up.

Sorry to be asking so many questions, I was really hoping to have this all done with and resolved but I can't seem to get this figured out easily. Here's to hoping the next time I turn wrenches on this thing will be the last for awhile. 

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On 9/12/2021 at 9:12 AM, TTrax said:

Thanks, all fuel lines have been replaced with new ones a couple months ago. I am hoping that won't be an issue for awhile. I might make replacing them part of normal maintenance in the future with what you mentioned in mind.

I replaced mine once.  Turned out that I bought the line from a local tractor supply, more for yard tools.  Well they would collapse under heat and higher rpm. Took me a while to figure out.  Just saying if you went with a thin wall fuel line.

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1 hour ago, SpencerPJ said:

I replaced mine once.  Turned out that I bought the line from a local tractor supply, more for yard tools.  Well they would collapse under heat and higher rpm. Took me a while to figure out.  Just saying if you went with a thin wall fuel line.

This time I had ordered Gates fuel hose and installed it. The wall thickness appears to be fairly thick and it is braided as well. The original hose I had installed a few months ago was from O'reillys and was some unknown brand. When I changed it out this time (only a couple of months later), it was very hard compared to some I had left over. I am pretty sure the B12 I had been using had done something to that hose, it felt like fuel hose that was out of something that was 20 years old. 

I don't know why, but I can get 200-500 miles out of the bike no problem before it starts doing this again. I clean out the carb with compressed air and cleaner and I can get another 200-500 miles out of it. I can't see any debris in the fuel bowl when I clean it out. It isn't a complete plugging, the engine will idle and have a miss intermittently. Its like something is starting to build up over time. It just seems that it has to be something inside the carbs themselves since I have a fuel filter right at the inlet of the carbs. 

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3 hours ago, BlueSky said:

I would put a bottle of Gumout for high mileage engines in the gas tank, or Chevron Techron  

I might give it a shot, I have Seafoam in it right now but might try some of the others. My concern is that it isn't gum or varnish getting into the carb jets and passages but debris shedding from some parts of the carb that might have been damaged or dissolved by the B12. I will definitely give that a shot to see what happens. 

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Wonder what the heck this stuff is. Coming out of the smaller of the two holes on the engine side of the throttle plate. When scratched with a pick it comes off and seems rubbery in composition.  Anyone ever see anything like this? 

Carb junk 2.jpg

Carb junk.jpg

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When you say the smaller of the two holes, are you aware there are 3 holes between the engine and the throttle blade. The smallest of the holes is the idle Pilot outlet hole for the idle circuit.  This hole is passing a fuel/air mixture and if the black stuff is coming out of there, it could be a bad o-ring that is used in the pilot screw set. The other 2 holes appear to be air holes for vacuum the coasting enrichment valve assemble and piston valve/diaphragms.  You might have to remove the pilot screw and see what shape the o-rings are in. Be aware there is a spring, washer and o-ring in there and they can be hard to remove. You might need to stick a small stiff wire in there to work them all out and there are replacements available for a number of sources.

Hope this helps.

Rick F.

 

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