Earshaved 06 - black smoke, horrible idle, what next?? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 20 (permalink) Old 09-17-2016, 09:31 PM Thread Starter
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Question Earshaved 06 - black smoke, horrible idle, what next??

Note: This is my friend's 2006 that's experiencing the problem as my 86 is running great.

Hi all,

I know..it's another "I performed the earshave and now it runs awful" post, but I read the living hell out of this message board and after going through dozens of posts, I'm not sure what it could be - the exhaust blows out gray smoke and idles horribly after an ear shave. It appears to be running super rich in which no adjustments so far have fixed it. The only thing that differs is that this bike still has the factory exhaust and goat's belly in place.


I'm going to save everyone time by explaining what I've done so far:
- pulled both carburetors off, fully disassembled (
I've documented it here - https://www.vn750.com/forum/22-carbs-...y-process.html),
- cleaned and rebuilt the carburetors using all oem parts: air cutoff diaphragms, float chamber o-rings, drain bowl o-rings, mixture needle o-rings and float valves
- drilled out mixture needle plugs
- retained the 38 pilot but upgraded the main jet to a 138
- added 1 shim per needle
- K&N cone air filters

After reinstalling the carburetors and ensuring everything was hooked up correctly, I turned the engine over..it started up immediately. After running the choke for about 10 seconds, I turned the choke off. Black smoke was blowing out of each exhaust pipe. I made some adjustments to the mixture needles on each side to make them leaner (!!) (important note: during my rebuild process, I set each needle to about 1.7 turns out). No change. I gave it some light throttle and it began to make the delayed "chug" sounds. It idled ok, minus the smoking, but any time I gave it throttle, it would bog. If I gave it heavy throttle, the engine would die.

I spent over two weeks reading this message board and came to the conclusion that "hey, maybe the float valves are stuck or the floats themselves are out of spec"

I pulled the carbs and fully separated them. Nothing was out of place. I performed the fuel level adjustment as stated in the service manual: hold the float chamber at an angle in which the spring loaded rod on the float valve makes contact with the float tang and check that the mating edge is between the chamber ribs...each side checked out. I even checked to see if I accidentally pinched the vacuum diaphragms during install - both were fine.

I checked the choke tubes to ensure nothing was binding or had even the slightest possibility of being stuck...everything moved nice and free.

Today on 9/17, I reinstalled the carburetors in hopes that maybe something might have changed...it did not. The stock pipes continued to shoot out black smoke (with mixture needles at about 2 turns out), with no change in throttle response.

Why is this happening? Does this have anything to do with retaining factory exhaust pipes at the moment? I know that several people have reported that they've done the earshave but retained their factory exhaust pipes. Is there something else that I'm failing to realize that could be causing this problem?

Why is this 06 running so poor? I've exhausted (no pun intended) every resource that I can possibly think of, what do you guys suggest I do next?
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post #2 of 20 (permalink) Old 09-18-2016, 01:14 PM
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Hello Catharsys,

Too much fuel is the primary reason for the black smoke. Pipes, stock or otherwise, WILL have an affect of your pressure flow rate, but nothing you cannot tune out with the mixture screws, and ultimately will never be responsible for whatever color smoke they blow. You might try this: Bottom out your mixture screws, then back them out to 2.5 turns. Also, did you sync your choke butterflies when you had the carb off the bike? Possibly bubble level check your carbs or use a manometer to sync them?

Also, do you have any type of filters on the carb vacuum lines?

I'm running 136 mains with one needle shim each, stock pipes, two Uni-Pods, two mini-cones (for the vacuums), 2.5(R) and 2.75(F) turns out on the mixture screw, my elevation above sea level averages between 60' to 400' and she runs awesome.
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post #3 of 20 (permalink) Old 09-20-2016, 10:41 PM Thread Starter
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Thanks for the reply

Quote:
Bottom out your mixture screws, then back them out to 2.5 turns.
Originally, I had them at 1.7 turns, which is roughly what they were like from the factory. Since pulling the carbs apart to inspect and reinstalling them, each mixture is at 2.5 turns out.
Quote:
Also, did you sync your choke butterflies when you had the carb off the bike? Possibly bubble level check your carbs or use a manometer to sync them?
I inspected the throttle butterflies on each carb before and after the initial disassemble and rebuild - both sides open and close in sync.

Quote:
Also, do you have any type of filters on the carb vacuum lines?
Filters on the carb vacuum lines? I've never heard of that before but I can tell you both brass nipples are plugged off with vacuum caps since I switched to a manual petcock (23F-24500-11-00) from the Yamaha TW200 trail bike. Since it worked out so well on my 86, I decided to do it to this bike as well.

I probably should have mentioned that I've also coastered this bike as well., sorry I left that off my first post.

I just started the bike up a few moments ago and let it warm up and checked a few things. It idles ok but upon giving it throttle, it shoots out horrid eye burning smoke and bogs down and if given too much throttle, obviously it dies.

I can't see why it's running this rich with all the adjustments and tests performed already. What else am I missing?
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post #4 of 20 (permalink) Old 09-20-2016, 10:44 PM
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The carbs have to be delivering too much fuel somehow

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post #5 of 20 (permalink) Old 09-20-2016, 10:58 PM
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Put the stock jets back in and might need to to take the shims out.

Still have the stock setup on mine, runs great from 800-4000ft asl

Stock pipes, stock jetting..
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post #6 of 20 (permalink) Old 10-04-2016, 03:50 PM Thread Starter
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Thanks for the replies everyone. Yeah, I failed to realize that rejetting wouldn't be necessary if the stock pipes were left in place

I explained the situation to the owner and they said, "ok, I'll go ahead and purchase the Vance & Hines Cruzers". The pipes arrived last week and I got around to removing the stock system along with the goat's belly this last Saturday. I installed the Cruzers, along with new exhaust gaskets and here's what happened next: the bike started up immediately and idled fine, but when giving it throttle, it bogged down and wanted to die. I made sure each mixture needle was set to 2.5 turns out, for starters, and gently adjusted the base idle knob to run at 1,100 rpms, give or take. Same thing.

While the smoke isn't black when giving it throttle, it acts like it's still way too rich. I noticed something strange - when turning the main idle knob a little (1/10 of a turn or so), the idle would drastically increase as if I turned it a full 360 degrees. I had to turn it back so the idle wasn't running at a crazy 2,500 rpm.

So currently, I still have: 1 needle shim per needle, 38 pilot, 138 main and the Vance & Hines Cruzers (Part #31363) with the baffles in place and it's still running rich and bogging under throttle, even with adjustments. Shall.....I remove the needle shims and replace with the 135 stock jets or is there something else going on?

Catharsys
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post #7 of 20 (permalink) Old 10-04-2016, 04:53 PM
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pull the baffles and see how she runs(just as a test to see how rich you are),then go from there

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post #8 of 20 (permalink) Old 10-04-2016, 07:57 PM Thread Starter
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Quote:
pull the baffles and see how she runs(just as a test to see how rich you are),then go from there
Good idea..I'll try that out and report my findings.
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post #9 of 20 (permalink) Old 10-04-2016, 11:20 PM Thread Starter
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Just came in from outside. Pulled each baffle, started up and it still chugs hard when given throttle, and it reeks as well. I forgot how horribly loud it sounds without any sound restricting device, worse than the HD guys booming down the street every weekend.

What next, jets?
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post #10 of 20 (permalink) Old 10-05-2016, 12:17 AM
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Exactly how oiled up are those filters? It's not going to hurt it to start it without the filters for a minute unless you're doing it in a sand pit. If that much restriction is being caused by the heavily oiled filters give them a wash.
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