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Exhaust question

2K views 15 replies 3 participants last post by  mariosb11 
#1 ·
hi All,
I just bought a 1999 Vulcan Classic 1500 and its exhaust is pretty loud and I would like to tone it down a notch or two. I like a low rumble but the pipes that are on it are quite loud.

First, is there any way to tell what kind of exhaust it has, I looked over the pipes but found no markings on it.

Second, it has some popping on decel, low end power feels good but it sputters at higher end RPM's, from what I read it sounds like it may be running lean and possibly need a rejet (I don't know what was done to the bike in the past), I couldn't feel any puffing where the pipes bolt to the cylinder so I don't think it's a exhaust leak but if I put on different pipes I will have new gaskets, any ideas on other things I could check.

Thanks
 
#2 ·
Don't know about identifying the pipes, but you can measure the diameter and buy some baffles, like Quiet Core or some other equivalent, to tone them down.

Does it run especially hot at high RPM?
Is the air stock, or does it have an aftermarket hi-flow filter?
Have you ever removed the carb to see if the pilot screw plug has been drilled out? This would be a clue as to whether it has been rejetted or not.
 
#3 ·
I am a newbie to this so I may ask some basic questions.
The exhaust on there now are slash cut and look to be one piece all the way to the cylinder so I'm not sure how a baffle would be put in,

I believe it does run hot, I have bluing on the pipes by the cylinder

It has the stock air filter,

I will pull the carb off to see if the pilots crew has been drilled, just haven't found the time yet

If I understand correctly if it hasn't been drilled I could drill it out then back the adjustment screw out to see if that helps, but don't go more than two turns, if I need to go more than that then it probably needs a rejet
 
#4 ·
The exhaust on there now are slash cut and look to be one piece all the way to the cylinder so I'm not sure how a baffle would be put in,
Look up into the pipe with a flashlight and see if there are baffles up past the slash cuts. If so, you can either replace or wrap them. Here's a video on wrapping

https://www.youtube.com/watch?v=gcVdzsa-N5I

I believe it does run hot, I have bluing on the pipes by the cylinder
Do these pipes have heat shields? If the header pipe is blued, that is quite normal. If the heat shield is blued, it is not.

It has the stock air filter,
By itself, the new pipes should not require a new filter and jets, at least in theory, but in reality, it often does. These bikes are balanced from the factory with air, fuel and exhaust all designed for adequate performance, optimal mileage and minimal emissions all at the same time. This means they are set up a bit on the lean side for EPA rules. If you alter either the air or the pipes, you can increase air flow just enough to make it too lean. I've never been a fan of just replacing the pipes but not the fuel and air. Lots of guys do it, and lots of them have no problems, but each bike has it's own characteristics. What works on one bike might not work on the same model and year bike parked right next to it.

I will pull the carb off to see if the pilots crew has been drilled, just haven't found the time yet
You don't need to pull it off entirely; you can loosen it enough to tilt it up and look, leaving the throttle linkage attached. But you will have to remove the dog bowl, the tank, the fuel line from both the tank and the carb, and unscrew the clamp from the intake.

If I understand correctly if it hasn't been drilled I could drill it out then back the adjustment screw out to see if that helps, but don't go more than two turns, if I need to go more than that then it probably needs a rejet
Up to a point, yes. Carb theory is basically this: the first third of the throttle is the pilot circuit, the second third is governed by the needle and the top third of the throttle is in the main jet size. There's a bit more to it than that, but that's the Reader's Digest version. Here's a great site for more carb info:

http://web.archive.org/web/20140626041010/http://gadgetjq.com/keihin_carb.htm

and a how-to

http://www.vroc.org/faq/carb/carb-howto.html
 
#5 · (Edited)
Baffles

PatC
Thanks for the reply, I have a good starting point to go by now, one more question though on the baffles. My pipes turn out at the end and are one piece so I do not see how a baffle can be removed or replaced. I've attached a photo of the end of the pipe. I look down the pipe and I do see the end of a baffle but to my untrained eye it looks permanent. I also could not find any bolt that looks like it would hold them in. Maybe these are stock?
Sorry for the long reply time, we've had some great riding weather here and between that and work I've been pretty busy.

Also the front cylinder heat shield does have a slight bit of bluing on it. Also, When I got the bike I found the air cleaner installed on the wrong side and it blocked most of the port leading to the carbs.
 

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#6 ·
If you decide to remove the carb, DO NOT CHANGE anything. carefully strip it, clean it. make a note of the jet sizes, make a note of how many turns the screw is out from closed (count in quarters, every quarter makes a big difference). Be very careful with that screw. Its very fragile. a strong tighten home will bugger it for good. Just use your fingertips on a small screwdriver to turn it.
See if the needle has any shims on it, either above or below. Take pictures. Then come back here with the list so we can advise you properly. If you start fiddling without knowing what youre doing, it will never work properly again.

Have you read about coasters? there are black boxes on the front of the front pot under the pipe, and at the back on the back pot, under the pipe. From the factory they are connected by tubes to a gizmo on top of the engine. All of this can be removed if it hasnt already, and that will greatly reduce the decell popping.

Ask here before doing anything.
 
#7 ·
Hello Sunny bob,
Sorry for the long break, had a busy time lately and finally got to the carb on my cycle.
So the two jet sizes are 45 and 132, the mixture adjustment screw is 2 3/4 turns out and the needle has two spacers on top of the clip. The clip is on the 3rd position down from the top. Ive attached photos of all these.
The carb is a Kiehin CVK G380
I have cleaned out carb with some spray type carb cleaner, hopefully this is good enough to get into all the ports and everything.

I am going to order a coaster delete kit too, Thanks for that information, it is a much cleaner way than "marbling"

I am doing something wrong and cannot post any picts right now

Thanks

Mario
 
#8 ·
Your carb has been played with, and possibly replaced with the wrong one.
The 1500 classics had cvk 40mm carbs. the number you quote doesnt mean anything to me. measure the diameter, if its 40mm, thats ok. If its 38mm, thats an 800 vulcan carb, and your gonna work hard to make it work.

But your needle is wrong, no wonder you have a problem. The stock needle has no circlip or rings, and does not have any shims. I suspect you have a dynojet needle, these are primarily for drag racing engines, and are very difficult to dial in accurately for street use.

Settings for a 40mm carb on a 1500 with open pipes and air cleaner should be 46 pilot jet, 170 main jet, 2.5 turns out.
But that is with the stock needle. I cant help with what you have, maybe another here has more experience of adjustable needles.
 
#10 ·
I measured the inside of the carb (engine side) and it is a bit over 40cm (1.6") so it sounds like the correct carb.
I have attached the URL for some photobucket pictures and hopefully it works correctly. If not I will dig deeper and try again.

I am not into tweeking out every last bit of power I can from the motor, I am just looking to get rid of the cutout or sputtering on takeoff and also making sure I am not running to lean which I believe I am since my pipes are slightly discolored on the shield.

Thanks for your input on this, it is very helpful and I am looking forward to getting my bike back on the road before our holiday weekend next week

Mario
 
#12 ·
All aftermarket pipes discolour nowadays, because all engines now run "lean" compared to many years ago.

With the air cleaner cover off, and the engine off, look inside the carb as you twist the throttle quickly. There should be a sizeable squirt of fuel from the little brass peg on the bottom of the throat. If not, then the accelerator diaphragm might be perished, or the feed hole in the base of the bowl blocked.
This hole is the tiniest hole you will ever see, but that jet of fuel must be there for the engine to work properly.
 
#13 ·
The accelerator pump is working, I saw a good squirt of fuel when I took the carb off an moved the throttle linkage. I think at this point I am going to get the two jets you suggested earlier along with a stock needle, this way I will know what is in the carb. Another question, I still have the stock air cleaner on the bike, will that make any difference with what jet is selected?

Thanks again for your help.

Mario
 
#15 ·
the needle and jets I suggested are for after market air filter and pipes.
You can keep the same air cleaner case, but buy a K&N air filter. It should come with a small tube of red oil.
Lightly oil the whole of the K&N filter before using it. If you put too much oil on, no big deal, it will just run out the bottom of the cleaner.
If you feel the need to keep the stock air filter (but why?) the jets should be 45 and 138 and about 2 turns out.
 
#14 ·
If it was mine, I'd take it for a spin around the block with the air cleaner out and see if that makes a difference.
 
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