Newbie... popping question - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 11 (permalink) Old 07-23-2019, 07:17 PM Thread Starter
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Newbie... popping question

Hi, trying to find a solution to my bikes severe popping on decel.
Its a 1985 VN750 with no emissions on it so cannot do the marble mod.
Has aftermarket exhaust as far as I can tell.
Any suggestions on what could be causing it?
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post #2 of 11 (permalink) Old 07-23-2019, 09:27 PM
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Some possibilities:

Lean fuel mixture
Sticking coast enrichers
Vacuum leak
Incorrect air mixture screw adjustment

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post #3 of 11 (permalink) Old 07-24-2019, 11:36 AM
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What he said ^

When you say it has "no emissions" on it, are you saying the hoses and reed valves have been removed....and replaced with what?
I still see the stock airfilters.

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post #4 of 11 (permalink) Old 07-25-2019, 08:54 AM Thread Starter
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From my understanding in 1985 the VN750 imported into Canada did not have any emissions devices on it, which is why they where not imported into the USA until 1986.
No hoses or reed valves and the stock airfilters have no place for the hoses, just straight carbs and airbox with crank vent and a smaller vent hose running from the airbox itself.
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post #5 of 11 (permalink) Old 07-25-2019, 09:21 AM
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There were tariffs on Japanese bikes 700cc & up in 1985. Kawasaki sold a Vulcan 700 (699cc) into the U.S. in '85. I have one. I didn't realize they sold a 750 into Canada in '85. Interesting.
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post #6 of 11 (permalink) Old 07-25-2019, 09:32 AM Thread Starter
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Quote:
Originally Posted by Mikey700 View Post
There were tariffs on Japanese bikes 700cc & up in 1985. Kawasaki sold a Vulcan 700 (699cc) into the U.S. in '85. I have one. I didn't realize they sold a 750 into Canada in '85. Interesting.
Ah k, maybe the info on the missing smog junk I was given was wrong.
It is an '85 750 though lol..
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post #7 of 11 (permalink) Old 07-25-2019, 09:57 AM
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Quote:
Originally Posted by Rabidcanadian View Post
From my understanding in 1985 the VN750 imported into Canada did not have any emissions devices on it, which is why they where not imported into the USA until 1986.
No hoses or reed valves and the stock airfilters have no place for the hoses, just straight carbs and airbox with crank vent and a smaller vent hose running from the airbox itself.
It has coasters where the reed boxes used to be.

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post #8 of 11 (permalink) Old 07-25-2019, 09:57 AM
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Your photo clearly shows a "coaster", a metal plate to cover the removal of the reed valve. So you're saying this was done at the factory?

The air boxes should only have the rubber boot going to the carbs and the small hose vacuum line going to a T fitting which branches to each carb.

Regardless of this, you should check the intake for leaks, and adjust the "air screw" (which is really a fuel enriching circuit) farther out. (In=Lean, Out=rich)

It's possible that because of the aftermarket exhaust you might need to re-jet the carbs (richer)

I too was unaware that Canada received 1985 750's. Much less ones without black engines.

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post #9 of 11 (permalink) Old 07-25-2019, 10:40 AM Thread Starter
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Quote:
Originally Posted by Knifemaker View Post
Your photo clearly shows a "coaster", a metal plate to cover the removal of the reed valve. So you're saying this was done at the factory?

The air boxes should only have the rubber boot going to the carbs and the small hose vacuum line going to a T fitting which branches to each carb.

Regardless of this, you should check the intake for leaks, and adjust the "air screw" (which is really a fuel enriching circuit) farther out. (In=Lean, Out=rich)

It's possible that because of the aftermarket exhaust you might need to re-jet the carbs (richer)

I too was unaware that Canada received 1985 750's. Much less ones without black engines.
I'm not sure about the coasters being factory or not as I cannot find much info about this year, I do know that there are no vacuum lines going to or from the carbs.
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post #10 of 11 (permalink) Old 07-25-2019, 12:10 PM
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There would be one on the right side carb if the emissions hadn't been removed. It has a plugged hose on it now.

Should still have a vacuum petcock, I think, hooked to the left side carb.

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__________________________________________________ ____________
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