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post #1 of 36 (permalink) Old 10-18-2007, 12:08 AM Thread Starter
 
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Performance questions

I've got questions regarding the performance of the Vulcan. A couple of coworkers have thrown my carefully laid plans into disarray, and I wanted to get the straight poop from my Vulcan brothers and sisters.

I've had my '85 VN700A1 for a year and four months. When I got it, it had a leaking gas tank, which I fixed. I have been riding and fixing and riding and fixing and thus far the interval has been getting longer for riding and shorter for fixing. Right now, I know the carbs, which I had off and cleaned (and a buddy checked the jets and pronounced them clean), are out of sync. Cindy is going to help me get that dialed in. The mixture is rich, but I don't want to start tuning on that until I get the carbs synced.

My problem is that right now, either in 4th or 5th gear on flat ground with the throttle wide open, my Vulcan tops out at about 72 MPH. This isn't right.

I was talking to a couple of coworkers who ride, and they both told me that carb sync only really affects idle smoothness instead of outright performance. They suggested that the carbs may have to come off again and that the jets weren't really clean.

I'm just trying to get the real story so I can get my bike performing up to scratch. Like I said, Cindy is going to come and help me wrench on it, but I figured I would bother everybody with my questions rather than just her.

Does carb sync affect performance and top speed? If not, what else may need to be adjusted to get this running right? I would prefer to do the work myself than paying a garage $100/hr or more...

Thanks all,
--Storm
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post #2 of 36 (permalink) Old 10-18-2007, 01:12 AM
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Check your fuel flow from the petcock. There are some filters in the tank.

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post #3 of 36 (permalink) Old 10-18-2007, 05:42 AM
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Have you checked/cleaned the air filters?
Also, have you been using seafoam?

How many miles are on the bike?
With a bike that old, it could be that ya aren't getting complete compression due to normal wear of engine parts.


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post #4 of 36 (permalink) Old 10-18-2007, 07:04 AM Thread Starter
 
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Quote:
Originally Posted by niterider View Post
Check your fuel flow from the petcock. There are some filters in the tank.
I just rebuilt the petcock a month and a half ago, and the tank filter was clean.

Quote:
Originally Posted by hyperbuzzin View Post
Have you checked/cleaned the air filters?
Also, have you been using seafoam?
Air filters were cleaned in the spring. And I use seafoam about every other tank.

Quote:
How many miles are on the bike?
With a bike that old, it could be that ya aren't getting complete compression due to normal wear of engine parts.
About 21,800. Very low mileage for a bike this old. In fact, I was concerned about dry rot in the rubber parts because the mileage was so low. The previous owner had the bottom end rebuilt two years ago. Finally, there are newer Vulcans on this forum that have more mileage than this bike does.

I'd love to hear from other VN700 owners on here.

Last edited by storm16; 10-18-2007 at 07:17 AM.
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post #5 of 36 (permalink) Old 10-18-2007, 09:57 AM
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[QUOTE=storm16;44799]I just rebuilt the petcock a month and a half ago, and the tank filter was clean.



Air filters were cleaned in the spring. And I use seafoam about every other tank.



About 21,800. Very low mileage for a bike this old. In fact, I was concerned about dry rot in the rubber parts because the mileage was so low. The previous owner had the bottom end rebuilt two years ago. Finally, there are newer Vulcans on this forum that have more mileage than this bike does.

I'd love to hear from other VN700 owners on here.[/QUOTE]

My VN has 28730 miles and makes 80+ mph in 3rd gear.
Here is a pic:
http://i35.photobucket.com/albums/d1...r/000_0040.jpg
I still think the problem is fuel delivery. Check the vaccuum hose that controls the on/off of the petcock. Also check that the tank vent properly.

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Last edited by niterider; 10-18-2007 at 10:01 AM. Reason: more info:
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post #6 of 36 (permalink) Old 10-18-2007, 11:03 AM
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My VN will do a little better than 80 in third gear... your problem is either in fuel delivery or in spark.

Have you checked to make sure that there are no kinks in the vacuum hose going to the petcock and that the fuel delivery hoses aren't kinked?

Ya might even try a "speed run" with the petcock set to prime (all the way back - PRI ).

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post #7 of 36 (permalink) Old 10-18-2007, 11:31 AM Thread Starter
 
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Quote:
Originally Posted by niterider View Post
My VN has 28730 miles and makes 80+ mph in 3rd gear.
Here is a pic:
http://i35.photobucket.com/albums/d1...r/000_0040.jpg
I still think the problem is fuel delivery. Check the vaccuum hose that controls the on/off of the petcock. Also check that the tank vent properly.
The fuel lines and that vacuum line were all replaced when I had the carbs off in the spring. How do you check the tank venting?

Quote:
Originally Posted by curtis97322 View Post
My VN will do a little better than 80 in third gear... your problem is either in fuel delivery or in spark.
80+ in 3rd gear? Thats what I want to hear...Plugs were replaced last fall when I did my winter maintenance. They were checked when we got the carbs back on and together, and they were clean and dry.

Quote:
Have you checked to make sure that there are no kinks in the vacuum hose going to the petcock and that the fuel delivery hoses aren't kinked?
As I said above, all three were replaced in the spring. I did lengthen the fuel lines a couple of inches to make it easier to get the tank off (since every piece of maintenance I have done involves pulling the tank...), but I checked them and they go straight back along the bottom of the tank then straight down into the carbs.

Is this the only place where I could have a vacuum leak?

Quote:
Ya might even try a "speed run" with the petcock set to prime (all the way back - PRI ).
A fine idea. I might run the hills on 211 tonight if I can manage to get out of the office before 7... To be honest, I avoid PRI like the plague because when I first got the bike (my first bike at that), I thought PRI was for Primary and tried to ride like that. Oops.

--Storm
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post #8 of 36 (permalink) Old 10-18-2007, 01:14 PM
 
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Storm, I have a very similiar problem. I just got mine back from the shop which professionally cleaned the carbs. The Vulcan idles perfect, but when I go to start out in first gear it seems like I am starting out in fourth. When I apply 1/4 throttle it bogs down, when out on the road it will not go over 70 mph and seems to have a loss in power. I have also replaced the air filters, spark plugs, and changed the oil all within the last 3 months. I am thinking maybe a air/fuel mixture problem or spark problem dealing with the coils or plug wires. My Vulcan is a 1998 with about 4000 miles and sit for approximately 3 yrs before I bought her. This is also driving me nuts and I lost all season to enjoy riding her. So if anyone runs into a fix please let me know.

Bill
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post #9 of 36 (permalink) Old 10-18-2007, 01:36 PM
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I still think that you have to take a good look at your fuel delivery. Also make sure that the choke is all the way opened. Not just on the lever but at the carbs. Choke adjustement.

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post #10 of 36 (permalink) Old 10-18-2007, 02:17 PM
 
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Niterider, I already removed the peacock from the tank and inspected both the filters and the fuel delivery system and everythings seems to be in order, gaskets, seals. I also had the shop adjust the choke in which they said that it did not need an adjustment. I did not leave it there because of the running bill, but I figure it could be a vacuum leak, air/fuel adjustment or improper spark (coil/wires) that could be causing the problem. I figure over time I will have the problem fixed, I do have all winter to try and find a solution.
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