Front cylinder way too rich - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 04-28-2017, 10:49 PM Thread Starter
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Front cylinder way too rich

Last week I finished ear shaving, rejetting and putting on new exhaust system. I bought the colortune because I knew I was running rich but could not seem to get the right adjustment via the rpm drop and adjust method. So when I put the colortune on my rear cylinder, the mixture seems in the ballpark @ 2.5 turns out but on the front cylinder @ 2.5 - all the way out and in the color does not change indicating it is running really rich regardless of the number of turns. Also when the idle drops when in trying to lean out the front cylinder I've tried turning it up but it's like the idle adjuster is as far as it can possibly go. It almost seems as if someone prior to me has tuned the bike to one extreme and I'm having an impossible time leaning out the front cylinder/carb. When I turn the fuel mixture screw for the front cylinder in all the way the bike dies and the color stays the same bright yellow regardless of all the way in or out, but when I turn in the screw on the rear cylinder it does not die. I'm really lost here and would like to fix this before I ride her again. Any help/input would be greatly appreciated. Thanks

Last edited by MikeIronTyson; 04-28-2017 at 11:16 PM.
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post #2 of 9 (permalink) Old 04-28-2017, 11:58 PM
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Choke plunger isnt stuck up front is it?

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post #3 of 9 (permalink) Old 04-29-2017, 09:39 AM
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Make sure the vacuum line on the front carb is not wet with gas. Also, the vacuum port on the petcock should always be dry. Wet would mean the petcock is leaking through the vacuum port.
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post #4 of 9 (permalink) Old 04-29-2017, 07:33 PM Thread Starter
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No it is not.
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post #5 of 9 (permalink) Old 04-29-2017, 07:43 PM Thread Starter
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The vacuum line at the end where it hooks up to the carb on the front carb from the petcock does have a minute bit of gas. The vacuum port on the petcock itself is dry. The capped vacuum port on the rear carb had gas in it as well, more than the front carb. But that one from my colortune indicates it is okay. I do remember when I rejected the carbs that the diaphragms seemed thin but did not notice any holes. I turned my front carb screw all the way in and it did not kill the bike and it did not seem to make any noise difference either, so I'm getting spark via the colortune and the plugs are fouled but turning it in all the way does not seem to have killed the bike, could I have been riding on one cylinder this whole time???. And just to clear things up, dumbass me was testing the wrong spark plug for the carb I was testing last night. So when I wrote it up, the bike dying was from me testing the rear cylinder, which is the one that seems to be doing okay.
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post #6 of 9 (permalink) Old 04-29-2017, 08:11 PM
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You can take the plug wires off the front cylinder and see if it runs any different. If the front was firing, the idle should be a lot lower.

Or, you can unplug the rear cylinder and see if it starts at all.

You can also very carefully touch one plug wire back onto the plug while it's running and see if the idle picks up. But try not to get zapped.

Running on one cylinder might explain why you can't set the idle high enough, it may be cranked all the way up.

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post #7 of 9 (permalink) Old 04-29-2017, 09:20 PM
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when you changed jets did you also clean the carbs? might be flooding from sticky float needle.or is it possible you knocked the float out of adjustment?

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post #8 of 9 (permalink) Old 04-29-2017, 11:37 PM Thread Starter
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when I have both caps off the front cylinder, it turns but won't run, when I have both caps off the back cylinder it runs but only if I give it throttle, won't stay running with the idle screw all the way up. And when I have all the plugs in, the bike runs without choke and idles smoothly and sounds much stronger than when only the front cylinder caps are on. So that eliminates the cylinder problem. Both front plugs are fouled.
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post #9 of 9 (permalink) Old 04-29-2017, 11:58 PM Thread Starter
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The carbs were spottless. I believe the first previous owner had them cleaned before I had bought it off the previous owner who said he rode the bike about 5 times in the past 9 months. I'm going to take out the carbs tomorrow and inspect them. I do remember that when I replaced the main jet on the front cylinder carb that the whole assembly came off and I had to unscrew the jet apart from the bottom of the unit and screw in the new main jet and then screw the whole unit back into the carb. That part took me aback because in the instructions the main jet is supposed to just unscrew off and then you screw in the new one on but I had to kind of just guesstimate how hard to screw the whole unit back on.
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