Kawasaki VN750 Forum banner

21 - 40 of 54 Posts

·
Registered
Joined
·
14 Posts
I'm running with the stock exhaust. Earshave and jetting are the only mods so far. I contacted an old friend of mine who is also a certified Kawasaki tech/mechanic. His opinion is that I should re-install the stock air box or I will be fighting this issue for a long time. His experience is that with the pods installed that there is not enough velocity to properly lift the slides and that is why I'm not getting any power!
Other opinions?
Thanks,
Steve
 

·
Registered
Joined
·
7,754 Posts
Hundreds, probably thousands, of earshaved Vulcans are shaking their heads.

My first thought was a dirty pilot jet/idle circuit, but I need to read more and I'm out of time right now, will check more later.

If a slide isn't lifting, it can easily be a cracked diaphragm or the dia. isn't seated properly at the top cover. Do the woosh test. - remove pod, lift slide to the top and release it, listen for a steady woosh sound and note there should be some resistance as the slide drops. If it snaps back down with gravity, or one side has a different sound, the diaphragms need checked, re-seated, or replaced. Don't mix slide needles, they're different on each carb.

I'm earshaved on stock exhaust with stock jets and slide settings.

Make sure the carb bowl vent is sheltered from wind. Wind on the vent will cause bogging. Where do you have your vent? Placement is critical.

edit: I now see this is an older thread and there was just a couple of posts to catch up on. gotta go...
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,078 Posts
142/40 is what you'd run with a free flowing exhaust AND an earshave. many have gotten away with stock jetting with just an ear shave,but each bike is different. my bet is you're bike is running too rich

Sent from my LGL34C using Tapatalk
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,078 Posts
oh,and how about an introduction in the newbie section?

Sent from my LGL34C using Tapatalk
 

·
Registered
Joined
·
14 Posts
I checked the slides and they are properly seated and swooshing properly when lifted and released. i installed the 142 /40 main and slow jet per suggestion. i don't smell gas in the exhaust even when revving it up on my lift. i did the needle shim also using 2 shims per. If anything, it seems very lean to me. It starts up very easily and idles perfectly at 1k but the idle does not change at all even when I screw the idle adjusting screw all the way in or 5 turns out (both carbs of course). I temporarily taped up the K and N pods with masking tape leaving only about 3/4" open at the small end of the pods to restrict the air intake but it didn't seem to change the performance much. Still had no power and could only get it to 70 mph.
Gonna go back to stock jetting and remove the shims tomorrow and see what happens. Thanks for all the replies so far.
How do I get to the newbie section for an intro?
Thanks,
Steve
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,078 Posts
it's in the vn750.com news section,under newbie check in

Sent from my LGL34C using Tapatalk
 
  • Like
Reactions: MSattler

·
Registered
Joined
·
7,754 Posts
I checked the slides and they are properly seated and swooshing properly when lifted and released. i installed the 142 /40 main and slow jet per suggestion. i don't smell gas in the exhaust even when revving it up on my lift. i did the needle shim also using 2 shims per. If anything, it seems very lean to me. It starts up very easily and idles perfectly at 1k but the idle does not change at all even when I screw the idle adjusting screw all the way in or 5 turns out (both carbs of course). I temporarily taped up the K and N pods with masking tape leaving only about 3/4" open at the small end of the pods to restrict the air intake but it didn't seem to change the performance much. Still had no power and could only get it to 70 mph.
Gonna go back to stock jetting and remove the shims tomorrow and see what happens. Thanks for all the replies so far.
How do I get to the newbie section for an intro?
Thanks,
Steve
Sounds like you might be trying use the air adjustment screws to set the idle speed. There's one on the side of each carb, usually set around 2 to 2.5 turns out.

The idle adjustment is a single black knob on the left side that sets the idle on both carbs.
 

·
Registered
Joined
·
14 Posts
Sprockster

Thanks for the reply. I hear you. I'm aware of the difference between the idle speed adjuster and the 2 air/idle screws. I set the the 2 air/idle screws out 2 1/2 turns to begin with and it idled perfect at about 1k but it doesn't change when I mess with the 2 air/idle screws which I find really baffling.
Steve
 

·
Registered
Joined
·
7,754 Posts
Sprockster

Thanks for the reply. I hear you. I'm aware of the difference between the idle speed adjuster and the 2 air/idle screws. I set the the 2 air/idle screws out 2 1/2 turns to begin with and it idled perfect at about 1k but it doesn't change when I mess with the 2 air/idle screws which I find really baffling.
Steve
I thought so after I saw your intro post. You don't do that much wrenching and not know the differences. :)

When a mixture screw doesn't respond to adjustment, that sometimes means the idle is set above the point where that circuit takes effect. The idle rpm could be right where it belongs, but the setting required has the carb slide/butterfly set above the point of the idle circuit. One trick with automotive carbs is to bring the idle below normal, then do the mixture adjust for highest rpm or highest vacuum.

Or, it can mean the circuit is clogged, so the screw has no effect.

An air leak on a boot can also affect adjustment ... Does your rpm hang any after a rev, slow to come back down?

Do your plugs show a lean color, or rich?
 

·
Registered
Joined
·
730 Posts
You don't need to re-jet with the ear shave
I wish I had listened to this a long time ago, hahaha.

I rejetted to 142/42 and mine runs really rich, I only get 36 MPG average. Hauls ass! but you can always smell it running a bit rich when you really crack the throttle

I'll pull 'em out and put in some fresh shiny 138/38's in someday when I get the gusto back up to pull the carbs again
 

·
Registered
Joined
·
14 Posts
Thanks again for reply. I've been gone for about a week on a ride with friends. We rode up to Oregon and back down the California coast. It finally cooled down out here in California and was actually a bit chilly in the mornings in Oregon. We're pretty thin blooded out here! lol
I'll mess with the different settings and get back to you. I really like this little 750 and I know that I'll get it running great soon. What should I expect as a top speed just for reference?
Thank,
Steve
 

·
Registered
Joined
·
730 Posts
I believe the officially posted top speed is 110 mph, I can cruise mine easily around 80-90 with a little room left (though I've never pushed it above 90) and mine has plenty of punch at 70 in 4th gear. This bike likes to rev! The engine really wakes up above 5k rpm and will hold revs around 4-5k all day long without a fuss. I used to shift it like a car, nowadays though I rarely use 5th gear unless I'm cruising for an hour+
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,078 Posts
top speed on mine was 9500 rpm in fifth.lol

Sent from my LGL34C using Tapatalk
 

·
Registered
Joined
·
730 Posts

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,078 Posts

·
Registered
Joined
·
730 Posts
Thought I might add a little info I found out when looking at my stock jets taken out after an earshave...

2005 VN750 (North American Non-California Model)

Stock Pilot Jet = #38
Stock Main Jet = #132

No wonder I was so lean all the time! I've heard reports of 38/135 or 38/138 being stock size but 38/132 explains a lot of my lean issues (alongside the absolutely crusty state of the carbs when I pulled and cleaned them)

I am rejetted currently to 42/142 and can smell gas when I crack the throttle, so I'll probably order some 135 or 138 mains and reinstall the 38 pilots since they're chem-dipped and clean now.

The jump from 132 -> 142 is ridiculous though! Way too rich for pods only. Live and learn...
 

·
Registered
Joined
·
7,754 Posts
132 main is really lean. Makes me wonder if someone leaned it way out because it was flooding some other way. The petcock is overlooked pretty often, and clogged air bleeds can also cause flooding in many carbs. You cleaned the carbs good, so it's functioning now.

42/142 is a huge swing to full rich.

About 42-44 mpg is the best I can do (stock jets). But I can't run a full tank without laying on the throttle, playing with the power. Hypermiling isn't a fun way to ride for fun. Maybe if I was milking my last gas dollar, I could do it. :) I guess 44 is close to Geo Metro or a diesel dasher, but more fun on two wheels.
 

·
Registered
Joined
·
14 Posts
Hi all
After ear shave, I went to 42/142 which I thought was fine with the K and N pods installed. I could not smell un-burnt fuel so I went up to 148 on the main and the 750 runs fantastic and I still don't get any fuel odor. I'm basically at sea level where I live. I've always heard the going up at least 4 sizes on the main jet is a good starting point when you eliminate the stock air box and go to pods! I think that all these Japanese bikes are jetted tooo lean from the factory to meat EPS stuff!
Steve
 

·
Registered
Joined
·
730 Posts
DAMN 148 main is huge! So long as it runs well, that's what really counts. Then again I have a needle shim in mine, so maybe mine runs through the midrange as if it has such a large jet... I'm at sea level, too, and agree with you that these bikes were jetted super lean to meet EPA req's

As for the 132 being custom installed, I seriously doubt it. The airbox was still installed on this bike when I got it with 12k miles on it, and the carbs were absolutely gross inside, so I seriously doubt somebody had been in there before I went in for the earshave. I'm very prone to think mine was jetted 132 from the factory.
 
21 - 40 of 54 Posts
Top