Testing Ear Shave, Rough at high RPM - Page 3 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

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post #21 of 47 (permalink) Old 04-10-2019, 12:29 PM
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I've never been a fan of this mod, mostly because those who do it use K&N screens instead of real air filters. But it also requires a lot of tuning to get right, and will never work perfectly at all rpms like the stock system. You have 3 problems. No filters, causing increased intake air flow, which leans out the air/fuel mixture, part of the exhaust removed, creating a loss of back pressure, further leaning out the air/fuel mixture, and you have the PAIR system still hooked up. You need to completely remove and **** can that whole system. Remove the hoses at the heads and cap where the hoses went. Remove the valve behind the gas tank that those hoses connect to, and remove the vacuum hose from the rear carb and plug the fitting on the carb. Since you no longer have a stock airbox, what did you do with the hose that went from the 3 way valve under the seat to the airbox? If you have a CA model, all the evap crap needs to be removed as well.

I would use UNI foam air filters with some kind of oil on them instead of the mesh screen type. They not only work a lot better at filtering the dirt out, but they don't lean out the air/fuel mixture as much. Also I would put some kind of baffle in the exhaust system to increase back pressure a bit. I have seen people use eye bolts in the exhaust to do that. If there is anything bad about carburetors, it's that they have a limited tuning range. With no filters and open pipes, you will never be able to tune the carburetors to work properly at all rpms. It will be too rich at some speeds, to lean at others, and just right through a fairly narrow rpm range.

Harley riders that run straight pipes hated EFI when it first came out. But then they discovered it could be tuned to provide a perfect mixture at all engine speeds, and they could run open pipes without destroying their engines. Apparently loud pipes were more important than keeping their bikes electronics free.

Kawasaki put a lot of work into designing the stock intake and exhaust systems, mine always worked perfectly idle to redline. It seems most people remove them just for looks. I personally love the '80s Japanese look of the Vulcan 750. And stock it is faster than a stock Honda Shadow 1100 Spirit.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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post #22 of 47 (permalink) Old 04-10-2019, 03:08 PM
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Hmmmmmmmm, Jerry, do you wanna race when I get mine back together? Ran my 85 motor for over 5 years, yes five f£€uking years, all year long, ridden wet and put away hard, through ALL four seasons, with no loss in compression, with K&N filters, 1100 feet, 140/40 on the jets, 2 shims on the needles, degoated with Screaming Eagle mufflers, WITH NO PROBLEMS. Damn. It feels like deja Vu around here. Just because you can't tune a Vulcan does not mean it can not be done. This forum is full of information on how to tune a vn700/750, free for the taking. Please do not discourage others from doing something you are not capable of doing because PLENTY of people have SUCCESSFULLY tuned a vn with K&N pods and no goats belly. Maybe you should stick with mopeds.


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post #23 of 47 (permalink) Old 04-10-2019, 03:11 PM
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And I will say it again, K&N filters ALSO use the filter oil you so highly speak of on your Uni filters. How well would those Uni filters work without oil? Damn I am sick of sounding like a broken record

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lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

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post #24 of 47 (permalink) Old 04-10-2019, 03:14 PM
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Harley riders hated EFI because they knew how to tune their carburators. Drag pipes are not the most efficient exhaust. Most people that know how to tune at least put a muffler with a little bit of a baffle for some back pressure

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lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
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post #25 of 47 (permalink) Old 04-10-2019, 05:58 PM Thread Starter
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Quote:
Originally Posted by VN750Rider/Jerry View Post
You have 3 problems. No filters, causing increased intake air flow, which leans out the air/fuel mixture, part of the exhaust removed, creating a loss of back pressure, further leaning out the air/fuel mixture, and you have the PAIR system still hooked up.
When you say "leans out the air/fuel mixture", I read that I have more air going into the engine. Adding fuel to compensate, then means more total power.

I left the GB on for its supposed scavenging effect. It also tames down the volume. I want loud, not defining.

Quote:
Originally Posted by VN750Rider/Jerry View Post
Since you no longer have a stock airbox, what did you do with the hose that went from the 3 way valve under the seat to the airbox?
I put a crankcase filter on it.

Quote:
Originally Posted by VN750Rider/Jerry View Post
If you have a CA model, all the evap crap needs to be removed as well.
Fortunately not a CA model!

I won't have time to play with it until Saturday. I am going to remove the shims, put on filters, and see where I am at.


'89 Vulcan 750 Bought 4/12/18 @ 17805.9 miles $800
Purchased stock. Wrecked once
21029.8 miles & counting

Completed modifications:
Removed mufflers, straight pipes out of GB
110/90 Front Tire
Pick-up coil re-gapped to .020"
Compufire 55402 r/r series regulator
USB Outlet + Voltmeter
Repainted Metallic Blue w/ new tank bages
Ear Shave (wo/ coasters) 38/138 + 1 shim

Planned modifications:
Custom LED turn signals
Windshield
Highway Pegs
(Possible) ignition advance
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post #26 of 47 (permalink) Old 04-10-2019, 06:14 PM
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If you were still running it without filters, I would try it with filters before removing shims. These carbs do not function well with open throats.
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post #27 of 47 (permalink) Old 04-10-2019, 07:03 PM
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Quote:
Originally Posted by Spockster View Post
If you were still running it without filters, I would try it with filters before removing shims. These carbs do not function well with open throats.
Yup either K&N on UNI pod filters. Try not to use the cheap Emgo pods as they block the air passages at the end of the carb

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lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
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post #28 of 47 (permalink) Old 04-10-2019, 07:06 PM
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Besides, Jerry, the mesh/screen type have paper elements, which the oil coats, creating filtration

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Support your local FREEBIRDS MC
1986/5 Vn700/750 Frankenfook cross eyed bitch "Mellisa Fayhe"
I am a BIKER and i'm proud.FREEBIRDS MC CENTRAL NY

lowered with progessive 412 10" shocks
rejetted for K/N Pods part#rc 2340
sportster seat

'I didn't lose my mind.i gave it away

BRING BACK WOLFIE."Peace and Carrots"RIP
"And I'm free...as a bird"John Lennon Free as a Bird
"I only carry when I have my pants on"Joe Robinson RIP aka Old Dog
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post #29 of 47 (permalink) Old 04-11-2019, 01:03 PM
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Ok ok, I get it. I will stop posting on this topic. I'm still not a fan of it, but to each their own.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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post #30 of 47 (permalink) Old 04-11-2019, 01:30 PM Thread Starter
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Originally Posted by VN750Rider/Jerry View Post
Ok ok, I get it. I will stop posting on this topic. I'm still not a fan of it, but to each their own.
If we all thought alike, the world would be a boring place indeed!


'89 Vulcan 750 Bought 4/12/18 @ 17805.9 miles $800
Purchased stock. Wrecked once
21029.8 miles & counting

Completed modifications:
Removed mufflers, straight pipes out of GB
110/90 Front Tire
Pick-up coil re-gapped to .020"
Compufire 55402 r/r series regulator
USB Outlet + Voltmeter
Repainted Metallic Blue w/ new tank bages
Ear Shave (wo/ coasters) 38/138 + 1 shim

Planned modifications:
Custom LED turn signals
Windshield
Highway Pegs
(Possible) ignition advance
Jason Pittenger is offline  
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