Front cylinder cutting out - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 38 (permalink) Old 03-16-2014, 06:05 PM Thread Starter
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Front cylinder cutting out

Last night I pulled and cleaned my carbs. They did have some gunk in them. I also cleaned the petcock. While I was there I removed the factory airbox for an ear shave. I'm waiting on my jets but I slapped it back together and went for a spin. Now my front cylinder cuts out under load. Its not bad in first gear but second and third is horrible. If I hammer down it picks back up but still cuts a little. But in the midrange it dies completely. Is this due to nkt having the jets in it yet, and if so why only one cylinder? The back one runs perfect. I tried swapping the plugs, and its getting good spark from the coil. Ideas?

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post #2 of 38 (permalink) Old 03-16-2014, 07:04 PM
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This is hard to pin down. We have folks here that say you don't need to rejet for just an earshave (keeping stock exhaust) and there are others that say you need to go to larger jets.
My thinking is perhaps you missed something cleaning the carbs, if the rear jug is running well and the front isn't. I remember reading a post once claiming that you need to use bigger jets in the rear than the front because the front runs cooler.

I think you might want to go through the carbs again and make sure both are whistle clean, the float heights are spot on and there are no tears or holes in the diaphragm. Make sure both choke plungers are working at the same time, and for a point of reference....I'd switch the pilot and main jets front to rear to see if that makes a difference.

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post #3 of 38 (permalink) Old 03-16-2014, 07:06 PM
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Check your float levels and carb boot seals. It worked before you took it apart- the front carb float is notoriously sticky.

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post #4 of 38 (permalink) Old 03-16-2014, 07:24 PM
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also double check the vent lines, (one each carb, in the center section between them), as well as the fuel lines.

a plugged vent line for the front cyl will cause all sorts of front cyl problems
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post #5 of 38 (permalink) Old 03-16-2014, 07:56 PM Thread Starter
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Quote:
Originally Posted by Knifemaker View Post
This is hard to pin down. We have folks here that say you don't need to rejet for just an earshave (keeping stock exhaust) and there are others that say you need to go to larger jets.
My thinking is perhaps you missed something cleaning the carbs, if the rear jug is running well and the front isn't. I remember reading a post once claiming that you need to use bigger jets in the rear than the front because the front runs cooler.

I think you might want to go through the carbs again and make sure both are whistle clean, the float heights are spot on and there are no tears or holes in the diaphragm. Make sure both choke plungers are working at the same time, and for a point of reference....I'd switch the pilot and main jets front to rear to see if that makes a difference.
I went through them both again today. I didnt get into the floats either time, this time I'll check them and set them just in case its hanging closed and cutting the fuel off. The diaphragms are good, I checked them both times Ive had the carbs off. The bike does have straight pipes on it so Im sure its lean, just can't imagine it only doing it on one cylinder. I'll check the floats , but everything else in the carbs looks perfect. Thanks for the help guys

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post #6 of 38 (permalink) Old 03-16-2014, 08:21 PM Thread Starter
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Quote:
Originally Posted by Kelly2001 View Post
Check your float levels and carb boot seals. It worked before you took it apart- the front carb float is notoriously sticky.

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Im gonna switch the carb boots next time I pull it down just to check. I'll pull the carbs again tomorrow and check the floats

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Originally Posted by michiganteddybear View Post
also double check the vent lines, (one each carb, in the center section between them), as well as the fuel lines.

a plugged vent line for the front cyl will cause all sorts of front cyl problems
I checked the vent lines, but I'll check them again.

"You cannot exaggerate about the Marines. They are convinced to the point of arrogance, that they are the most ferocious fighters on earth- and the amusing thing about it is that they are."

1993 VN 750 bobber/bagger mix named "Halfbreed"
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Custom wrapped straight pipes
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post #7 of 38 (permalink) Old 03-16-2014, 09:24 PM
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Is gas coming outta the front carb? Try looking up Wolfie backblow method.might have some Cruz in the float needle

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post #8 of 38 (permalink) Old 03-16-2014, 09:53 PM Thread Starter
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Is gas coming outta the front carb? Try looking up Wolfie backblow method.might have some Cruz in the float needle

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No fuel from front carb, and with the filters off you can watch the slide move up and down correctly. I'll try back blowing it, but my money is on a hung float now that someone mentioned it.

"You cannot exaggerate about the Marines. They are convinced to the point of arrogance, that they are the most ferocious fighters on earth- and the amusing thing about it is that they are."

1993 VN 750 bobber/bagger mix named "Halfbreed"
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Turn signals deleted
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NGK Iridium plugs
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MCCT conversion
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post #9 of 38 (permalink) Old 03-16-2014, 10:10 PM
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You can easily check fuel level in the bowls w/o pulling anything.
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post #10 of 38 (permalink) Old 03-16-2014, 10:49 PM Thread Starter
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You can easily check fuel level in the bowls w/o pulling anything.
To late. Ive got the carbs off again. Ive torn them all the way down. Neither float was hung that I found, and they both float. Gonna swap the bodies and boota front and rear and see if it follows them. If so ill swap the boots back to narrow it down.

"You cannot exaggerate about the Marines. They are convinced to the point of arrogance, that they are the most ferocious fighters on earth- and the amusing thing about it is that they are."

1993 VN 750 bobber/bagger mix named "Halfbreed"
Degoated
Turn signals deleted
Center stand deleted
Custom wrapped straight pipes
Ear Shave
NGK Iridium plugs
Mean Streak seat
MCCT conversion
Saddleman saddlebags
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