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So I finally got my 99 Vulcan back from the shop and just in time for the weather to turn around. I've read the verses like a lot of you suggested in my intro post and did some cleaning when I got it back. I don't have iridium spark plugs or the amg battery yet but will be looking to upgrade soon (I bought a brand new battery before I knew the difference). At any rate, I decided to go out for a ride today and everything seemed fine. I came home and figured what the hell lets go fill her up.

So, here's a little backstory. The bike hasn't really been run or ridden in years. The shop did a full carb clean and replaced all the fluids and lubed everything up, new plugs and air filters. I swapped out the air filters for K&N high flow ones and added a little sea foam in the tank when I got it back on Friday. I rode it around a bit Sat with no issue, other than me not being smooth of shifts. Today after I filled it up with 93 (first time filling it at the station) I got maybe 3 miles down the road and came to a light. It stalled out as soon as I tried to go and I couldn't get it going for the life of me. I ended up having to push it into a parking lot, failing miserably trying to jump it by popping it into first. My GF ended up having to meet me and I jumped it (killed the battery trying to get it started). I got it going and it stalled again on the way home -- repeated the process and luckily coasted into my driveway after another stall.

I let it sit for a few hours and went to go get some food. When I came back I read the POOGS posts and cleaned the hell out of the vent and let it sit. When I tried to start it again it was really hard to start but I got it going. It backfired really loud 2x before it started and honestly, it scared me pretty good. I played with the idle and got it to sit around 1000 rmp but then it would rev up to 4-5k without me touching anything. It did this like 4 or 5 times before I said screw it and took it for a short ride. I went maybe 5 miles with no issues and was able to fire it right up when I got back after shutting her down. I was happy but I'm not exactly confident in her yet after what happened earlier today.

My question is kind of open ended. What do you think it could be/do you think I'm safe to ride to work tomorrow or is that too risky? Is it possible that the seafoam broke up some of the crud in the gas tank and it clogged up for a bit or maybe it was a vacuum issue? What would cause it to rev up at idle like that/should I be worried about it. This is my first bike and I don't really know much so pardon any stupid questions.

I really want to ride it tomorrow seeing as it's going to be almost 70 here in MA Monday and Tuesday, I just really don't want to get stranded. I've already got the don't call me again speech (she isn't a fan of the bike lol).

Thanks!
 

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It doesnt sound like the carbs are in tune.I recently cleaned mine and had to adjust the fuel screws and test the ride number of times until it was in correct form. also..the coaster process very helpful to do...

when i first got my bike few years back i had the same issue of the loud backfires and repeated attempts trying to start after she was warm.I always thought the carbs where dirty but after cleaned it was basically adjusting fuel screws. the rev of rpms sounds like the choke to me...but i also read here...the rev up and down could be the carbs looking for the equality for running correctly....if the battery is weak,,also the backfire will occur as i learned..

If it was mine...i would check a couple things around the carb first.,,also push the choke with your finger and see if it lets loose on its on or it gets stuck...move the choke lever on top and you see the plunger move on the carb to direct your finger for testing...also stated in the verses I saw to make sure the filters are secure no gaps in the air box as that can cause issue for starting....from what i learned about mechanics is just because they fixed it doesnt mean its hundred percent...look into the components familiarize yourself with the bike that was a suggest someone gave me..and its helped a great deal with learning...
 

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93 octane is way to high for our bikes We use 87. and a dose of sea foam from time to time , You also may have a vacuum leak check the air switch behind the battery. There are hoses there that can be leaking.



So I finally got my 99 Vulcan back from the shop and just in time for the weather to turn around. I've read the verses like a lot of you suggested in my intro post and did some cleaning when I got it back. I don't have iridium spark plugs or the amg battery yet but will be looking to upgrade soon (I bought a brand new battery before I knew the difference). At any rate, I decided to go out for a ride today and everything seemed fine. I came home and figured what the hell lets go fill her up.

So, here's a little backstory. The bike hasn't really been run or ridden in years. The shop did a full carb clean and replaced all the fluids and lubed everything up, new plugs and air filters. I swapped out the air filters for K&N high flow ones and added a little sea foam in the tank when I got it back on Friday. I rode it around a bit Sat with no issue, other than me not being smooth of shifts. Today after I filled it up with 93 (first time filling it at the station) I got maybe 3 miles down the road and came to a light. It stalled out as soon as I tried to go and I couldn't get it going for the life of me. I ended up having to push it into a parking lot, failing miserably trying to jump it by popping it into first. My GF ended up having to meet me and I jumped it (killed the battery trying to get it started). I got it going and it stalled again on the way home -- repeated the process and luckily coasted into my driveway after another stall.

I let it sit for a few hours and went to go get some food. When I came back I read the POOGS posts and cleaned the hell out of the vent and let it sit. When I tried to start it again it was really hard to start but I got it going. It backfired really loud 2x before it started and honestly, it scared me pretty good. I played with the idle and got it to sit around 1000 rmp but then it would rev up to 4-5k without me touching anything. It did this like 4 or 5 times before I said screw it and took it for a short ride. I went maybe 5 miles with no issues and was able to fire it right up when I got back after shutting her down. I was happy but I'm not exactly confident in her yet after what happened earlier today.

My question is kind of open ended. What do you think it could be/do you think I'm safe to ride to work tomorrow or is that too risky? Is it possible that the seafoam broke up some of the crud in the gas tank and it clogged up for a bit or maybe it was a vacuum issue? What would cause it to rev up at idle like that/should I be worried about it. This is my first bike and I don't really know much so pardon any stupid questions.

I really want to ride it tomorrow seeing as it's going to be almost 70 here in MA Monday and Tuesday, I just really don't want to get stranded. I've already got the don't call me again speech (she isn't a fan of the bike lol).

Thanks!
 
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Discussion Starter #4
Thanks @Buddy that's good to know I'll give those a check and next time go with the 87.
 

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What exactly did the carb clean entail? a full disassembly, inspection etc., (I'm guessing not).
I had no syncing issues on my carbs even after multiple disassemblies (by me) including removal of linkages.

If it were me, I'd be wanting to pull those plugs to read them as a super easy step one to verify not ridiculously lean or rich. I'm curious if both cylinders will indicate the same condition or not. You could post a picture if you are not familiar or confident with color reading. best thing is to do a plug cut and read if you can. but pull even after running, idle and shut is better than nothing.
 

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Discussion Starter #6
gidaeon I'm not really sure what it entailed. I'm going to call them tomorrow because they're closed Sun - Mon. I was able to make it into work today w/ no stalling issue but I'm still getting a high rev at idle from time to time, my commute is only 5 miles so I figured I'd risk it.

Do you think I should try to fix it on my own if the shop guaranteed the work or will that void that? I don't want to try to be a backyard mechanic and have them say since I touched it they're not going to stand by the guarantee. I'm not sure how that works. Thanks for the replies guys!
 

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It's possible the Seafoam knocked some crap loose that got run into the carbs.

If you get it started, adjust the idle speed up a bit past 1000 rpms. (Idle should be 1100-1150) Make sure all your carb boots are TIGHT...a slight leak will cause the rpms to rise by themselves.

I'd put the battery on a good charger (like a Battery Tender Jr.) when not riding.
 

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Buddy mentioned an "air switch". This is the first mention that I remember reading about said air switch. Pray tell what is it? What does it do? I follow everything said in this thread except for that part as I have no clue about it.
 

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Thank guys! I rode home and back on lunch and the RPM thing only happened once so maybe it is a loose boot or bolt. I'm going to take the gas cap off tonight and give it a full clean and check all the bolts and hoses. I'll update with pics if there is anything (most likely will be) that I don't understand.
 

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when idling spray some starting fluid around the carb boots. if idle jumps up,loose or leaky boots.

Sent from my LGL34C using Tapatalk
 

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Hmmmm....hard to start/backfire???Mine was a sticking float....so now I turn Petcock "off" every time I park it!!!Problem solved...!!
 

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The air switch is on all Vulcans 750 its not just on Ca bikes. Its located under the seat behind the battery it looks like a round canister with a number of hoses coming out. One hose goes to the reed valve the other ones route to the carb and then other side of the reed valve . I had a issue with my bike when riding my idle would wonder and I at first thought it was a return spring on the throttle as it turned out the air box switch was defective and I had to replace it. Basically I had a vacuum leak and that caused the symptoms. Check all the the hoses that are attached and look for dry rot.
 

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The air switch is on all Vulcans 750 its not just on Ca bikes. Its located under the seat behind the battery it looks like a round canister with a number of hoses coming out. One hose goes to the reed valve the other ones route to the carb and then other side of the reed valve . I had a issue with my bike when riding my idle would wonder and I at first thought it was a return spring on the throttle as it turned out the air box switch was defective and I had to replace it. Basically I had a vacuum leak and that caused the symptoms. Check all the the hoses that are attached and look for dry rot.
I think your wording is confusing. You say it is located BEHIND the battery. To me that would indicate it is closer to the rear wheel when actually the air switch you talk about is on the side of the battery closest to the front wheel. I think it's more clear if you say the air switch is in FRONT of the battery,
 

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Believe he is talking about this

That is the air switch I am talking about. The location you may be right I remember it being under seat it may be in front of battery or in back but that is the air switch I replaced
 

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Discussion Starter #17
I looked at everything mentioned here and it all looked good. I sprayed the boots with some break cleaner and no issue. I followed the directions for POOGS and cleaned the hell out of the cap (it was cruddy as all hell). The idle issue hasn't happened in a while and it seems to be running really well, steady idle at 1000-1200rpm.

I've ridden through another full tank of gas and did about 20 miles today (commute) but one this is I can smell gas in the exhaust and I wasn't sure if that is normal or if that means it's running too rich.

I've never worked on a bike before or adjusted the air screws on carbs but do you think that's what I should do? Or, should I go with the "if it aint broke don't fix it" method and just leave her be since she seems to be running fine now (aside from what I think I smell). Thanks!
 

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I sprayed the boots with some break cleaner
Please be careful with brake cleaner. While some brands offer chlorine-free brake cleaner, there is still chlorinated brake cleaner being sold.

When burned, the chlorine releases deadly phosgene gas. Just a whiff can kill you, if you live, it will still mess you up terribly. Left untreated, you could still die days later. Phosgene gas was used as a weapon in WWI.

Sorry to interrupt, but I've been gassed with phosgene from brake clean sprayed into a carb. I wouldn't recommend it!
 

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Check the vacuum line that runs into the left carb, it should be dry. If it's wet, extra gas is getting fed through there via a bad diaphragm in the petcock. If there's gas in that hose, also check the oil for gas.

If the exhaust truly smells like gas, it must be running rich for some reason. Make sure the choke plungers don't stick.
 

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Discussion Starter #20 (Edited)
Is this the hose I should be checking?

It looks kind of wet so I think that might be the issue. I had it repaired at a shop and I'm under their 30-day guarantee so I'm going to bring it there in the morning if I can get it running.
 
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