Thinking I'm going to have to re-jet - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 09-02-2012, 03:04 PM Thread Starter
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Thinking I'm going to have to re-jet

Yes, another carb jetting post.
The PO did an earshave and put on Harley Dyna mufflers.
He re-jetted the carbs with 138/38 jets with the mixture screws out 2.5 turns.
He had Emgo filters on there, and I took them off and put on a set of K&N's.
The bike is a pain in the azz to start. It took almost 5 minutes the other day to start.
If I fully choke it it will flood. If I choke it half way it will start and run about 2 seconds and die. I had to hold the starter button down to keep it running the other day. As soon as I let off the button it would die.
After I was able to get it going, it ran fine. Going down the road it would stutter and bog. I believe it's the vent hose doing that.
When I go to start it hot, it will start really easily, then immediately die. I hold the throttle part way thinking it's flooding and it will run a few seconds and die.
There isn't much power on the bottom end.
I have went through the carbs after I got the bike. He had 2 shims on the rear carb, and one shim on the front. He had needles from a set of carbs from a 750 with J & K on the needles.
There are 1 shim on each carb now with the original H & M needles.
I took the filters off, and put the boots on them that go into the plenum and it runs a lot better. This was purely for testing purposes, and I will put the filters back on.
It acts like the timing is retarded and it needs to be advanced.
Anything else I need to look at? I haven't checked the clearance on the pickup coils yet.
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post #2 of 7 (permalink) Old 09-02-2012, 03:27 PM
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your issues sound more like a weak battery combined with a bad ground from battery box to engine. If this ground becomes loose or corroded, it causes hard starts, and poor idles. a bad battery also will give you the same symptoms.

Do you still have the goat belly (the exhaust thingy that crosses under the battery box to connect left and right pipes)? Also, what is your elevation. Have you done the pick up coil mod, and the coil relay mod? Both of which help starting issues.
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post #3 of 7 (permalink) Old 09-02-2012, 06:47 PM Thread Starter
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No, I haven't done either mod. And yes, the goats belly is gone.
I looked at the ends of the mufflers, and they are pretty black. I haven't looked at the plugs yet.
The battery is less than a year old, and it's an AGM type. All grounds are clean and tight.
The bike spins over fine when I crank it to start it. And it will fire almost immediately hot or cold, it rarely ever turns over 3 times before it does.
I'm going to clean the ignition switch contacts, and check the wiring harness to see if there is a problem. I will check the voltage at both coils and see if there is a difference or low voltage.
I'm at roughly 3300 feet elevation. +/- 100 feet
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post #4 of 7 (permalink) Old 09-02-2012, 09:06 PM
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yes you need to go up to 140/40's
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post #5 of 7 (permalink) Old 09-02-2012, 09:11 PM
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Quote:
Originally Posted by TSmith68 View Post
I'm at roughly 3300 feet elevation. +/- 100 feet
at 3300 feet, I wouldn't change the jets.
I think you have a vacuum problem (right side should be plugged) or stuck float/s
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post #6 of 7 (permalink) Old 09-02-2012, 11:46 PM Thread Starter
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I looked under the tank a while ago, and I realized my fuel lines are above the petcock.
They come off of the petcock, and go above my wiring harness, and they are at an angle and they go up an inch above the petcock, and then loop back down to the carbs.
So tomorrow I'm going to reroute them where they need to be and see what happens.
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post #7 of 7 (permalink) Old 09-02-2012, 11:47 PM Thread Starter
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I have a can of carb cleaner, and I'm going to shoot some quick blasts around the carb bases, and vacuum lines to see if there is a leak somewhere.
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