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According to Kawasaki the goats belly is called a “power chamber” as it’s the main source of back pressure for the system. You’ll get mixed opinions on it as I’ve searched this one heavily. Some will say you’ll lose some low end torque, others say they feel no difference. I left in on and just gutted the stock mufflers. To answer your other question, it weighs about 20lbs, and is a source of heat directly on the rectifier if you haven’t relocated it.
On the air filters, you’ll also get mixed opinions as to weather or not you need to rejet.
That probably doesn’t help much, but I’ve had the same questions
 

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If you look at all the posts regarding modifications being done on these bikes, almost everything has been done to these bike you can imagine. All kinds of exhaust mods from companies like Vance and Hines, to straight pipes with no cross pipes at all. Some mods with jet changes some without. Different ignition systems, and swapping to a single carburetor are among the newest. Changing the air filters is not really going to result in a huge increase in power but should help mpg. Unless you ride harder.

Most of the mods will get you better starting and better mileage. My problem is if my bike runs better I do not get better mileage. I ride it harder and my back tire wears out faster. No matter how fast I get to redline, I'm still at redline. My bike would get there with no modifications and with them it just gets there sooner. Also, stock it didn't start when hot very well. (I am curious as to what mileage you get with one carburetor above 90 miles an hour.)
 

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My advice on intake and exhaust mods is always, after each mod read the spark plugs and let them show you what you need.

My exhaust is stock but I did the earshave with Uni pk92 filters. It's doing just fine on the stock jetting, no sign of being lean at all. Still running the Denso plugs that came with the bike.

Runs great, gas mileage is not nearly as high as some report, 34 mpg. My back tire lasted 6000 miles, showing the cords now. I ride a bit hard. Every gas mileage run has lasted about 20 miles and then I'm back to twisting the wrist. It's a fun bike.
 

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Discussion Starter · #6 ·
My advice on intake and exhaust mods is always, after each mod read the spark plugs and let them show you what you need.

My exhaust is stock but I did the earshave with Uni pk92 filters. It's doing just fine on the stock jetting, no sign of being lean at all. Still running the Denso plugs that came with the bike.

Runs great, gas mileage is not nearly as high as some report, 34 mpg. My back tire lasted 6000 miles, showing the cords now. I ride a bit hard. Every gas mileage run has lasted about 20 miles and then I'm back to twisting the wrist. It's a fun bike.
34 mpg! The specified rated estimate is 50 mpg 6,000 miles a back tyre! I got 15,000 out of a 75 bhp rated BMW! Do they use rough tar on the roads round you? Sprockster, in biking terms here, you are a "speed" hooligan. Having said that I once got one of the 400s down to 31 mpg, thrashing back from somewhere, but that was an exceptional fast 90 -110 mph days ride, on roads with no speed "demon" cameras and very early morning, when idiots are still in bed and the roads are much quieter.
 

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Discussion Starter · #7 ·
If you look at all the posts regarding modifications being done on these bikes, almost everything has been done to these bike you can imagine. All kinds of exhaust mods from companies like Vance and Hines, to straight pipes with no cross pipes at all. Some mods with jet changes some without. Different ignition systems, and swapping to a single carburetor are among the newest. Changing the air filters is not really going to result in a huge increase in power but should help mpg. Unless you ride harder.

Most of the mods will get you better starting and better mileage. My problem is if my bike runs better I do not get better mileage. I ride it harder and my back tire wears out faster. No matter how fast I get to redline, I'm still at redline. My bike would get there with no modifications and with them it just gets there sooner. Also, stock it didn't start when hot very well. (I am curious as to what mileage you get with one carburetor above 90 miles an hour.)
Some thought provoking issues here, why in stock form is the VN 750va bad starter, is there a specific reason? Choke not rich enough, airways poor?
 

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Discussion Starter · #8 ·
I had NGK's fail on me unknown in the 8p and 90s and would probably use Denso spark plugs. With 4 plugs you would think the cylinders would roar into life! Perhaps the combustion chamber shape is restricting the gas "swirl" effect. What tyres are you using, mine has a Continental on the back and a Dulop on the front. Having said that I have had Chinese tyres Cheng Shin on the rear of my Eliminator's , (150/80 X 15s are hard to get here so both have 140's on the back), and then have performed in grip and durability amazing well. A friend has used more expensive tyres and lost grip and mine have held fast. An older friend told me there is the possibility, that they have more rubber compound in them, than the more progressive firms tyres, but I have not checked that theory out yet!
 

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Shinko tires on mine, the mileage is on par with what others report. I've had no complaints with them.

I think the hesitant starts are a combination of the factory pickup coil gap, lean carburetors, and low cranking volts if using a wet cell battery.
 

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Some thought provoking issues here, why in stock form is the VN 750va bad starter, is there a specific reason? Choke not rich enough, airways poor?
The two schools of thought in bad starts are primarily electrical vs fuel. My bike had me at the point that stopping for fuel would be an anxiety inducing experience. Ultimately for me, the fix was closing the pickup coil gap so of course I lean towards it being electrical. You ask why in your post and my response would be “engineering mistakes”, I guess this is the same reason you have to pull the engine to replace the stator or shift shaft!!
 

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Discussion Starter · #11 · (Edited)
Kawasaki is a big industrial concern, much bigger than Honda overall. Getting things wrong really hurts the company pride, probably someone got executed for not doing their best!

An Uncle of my Mother was captured by the Japanese in WW2 and I turned up on a Honda in the 80s. He made me park it round the corner!

They dual spark plug Classic racing singles, to get more power out of them. Then there is the Indian guy Somander Singh who cuts grooves in cylinder heads to make the spark paths more flame enhancing on older engines. On singles BSA discovered years ago that offset the induction tract, contributed to gas swirl n' Phil Irving used this technique on the Vincent " V " twins. A rough inlet tract can give more power, or a grill fitted over the carburettor mouth can add to disturbing the air-flow, smooth isn't allows the best. I remember Rover engineer's using the "barrel" swirling effect in the "K" series engine of the 90s and 2000s.

On multi's if U suspect a cylinder is misbehaving run the bike and touch the exhaust with a wax crayon, the one playing up will not melt the wax crayon. In across the frame fours, counting left to right, it is usually cylinder 3 that can be troublesome, in my experience.
 

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Here in California the opportunity to go faster than you are supposed to is ever present. Most people on the interstate are going 75 to 80 so a bike can run 85 to 95 and not really even stand out. When I started riding in Colorado I was in a "rural" area and could ride as fast as my bike(s) would go. Only had to watch out for birds, rabbits and sometimes cattle. Of course there were a lot of gravel roads also so I got good on those too.

I do not count on more than 90 miles before getting gas because I do not like switching to reserve. For tires I have had Avon Venom that I loved but they are expensive. I tried Kenda and they didn’t handle good enough for me. I think mine had Bridgestones on her when I first got it and I am running Dunlop now. The better the grip, the faster they wear out. If I were to slow down I could probably get tires that would last but then I wouldn’t have much fun. I corner harder than my son even around town so I like tires that grip. I don't like to keep track of my tire's mileage but my bike now has just over 27,000 miles on it. She was just under 14,000 when I got her so I guess my miles per tire is not too great. One more reason I am curious about going to the darkside.
 

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To answer another question you had, yes our roads can be pretty horrible a lot of the time, but they're working on them. The roads in WV are also very crooked, but we tend to seek the most curves we can find to ride on.

Considering Darkside myself, as curvy as the roads are, my chicken strips are wide and still like new, with the cords popping out of the center. I ride hard but I'm not a peg dragger, too much slick stuff on public roads.
 

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Indeed I believe the condition of the roads throughout the country are barely safe anymore for spirited riding. I really didn't believe I was a peg dragger, but; I scare the heck out of my son when we ride around town together. I used to ride my H2 750 hard on the mountain roads in the Rockies but I never leaned it over enough to make any sparks. The Vulcan really handles well except for the pegs hitting. It's low center of gravity and low seat height are part of why I liked this bike from the start. I hated having to tippie toe at the stop lights on my other 750. I can not wait to get it back on the road for my son to ride. He has no idea of what a cruiser the Vulcan is. Maybe I'll get it on video. He's on the short side like me.
 
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