VN750 that sat for a couple years - first orders of tune-up questions - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 6 (permalink) Old 06-16-2018, 05:16 PM Thread Starter
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VN750 that sat for a couple years - first orders of tune-up questions

Hey guys!
This is my first post, a neighbor of mine moved away and I was gifted his 1999 VN750. It's a great little thing, but it needs some love.

My first mission was to get it started. Some fresh fuel, New battery, oil, and a LOT of turning over and she's running. The brakes were rusty and I was able to ride it around the block - albeit the front forks are basically dead and it didn't roll freely. It's rolling almost free now - I can push it around.

Second mission - an easier start up. I don't know where to start and I need your help. When I first come out to the bike - it takes about 3-5 minutes of turning over. I'll get some rumbling and fumbling but it usually is running WHILE I am in the starter cranking it. About 5 seconds of this, some throttle (zero choke) and 2-3000rpm for 30 seconds and I can slowly let off the throttle.
Maybe it's getting too much fuel and the added air is takes it off. It's been warm a few times and I tuned the idle to 1500rpm - much lower and she runs pretty rough.

Any tips on what to do? I'm think running some seafoam through the gas tank, maybe new spark plugs. I don't have a ton of money to spend on this guy, I've got another motorcycle that has been my daily for some time that has a bit more need for the bigger $0.00 lol. So maybe I'll pull the sparks and sand them up - Check gap etc.

Should I try tuning the A/F? I'm not sure how to establish a base on it - I do know the carb was rebuilt (only 15,000 on the bike though!)

The idle also has a hard time returning to idle it's a slow downwind - a few to five seconds from 4000rpm. Maybe I just gotta soak everything in WD-40.

Thanks all!
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post #2 of 6 (permalink) Old 06-16-2018, 05:31 PM
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Sounds like dirty pilot jets and maybe the choke circuit is plugged. (rough idle below 1500) I'm not convinced it's rich on startup... Any black smoke or strong gas odor?

The rpms hanging could be an air leak at one of the boots, depending how bad it's hanging. I think these naturally have some 'wind down' because of the coast enrichers in the carbs, but an air leak will make it worse.

I would get the seafoam in there now while gas is still flowing. Was the gas tank cleaned?

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #3 of 6 (permalink) Old 06-16-2018, 05:47 PM Thread Starter
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Thanks for the quick response. I got out some spray start and got the girl running. I sprayed around and couldn't fine any air leaks and it seemed to be running much better today. Maybe not the best vacuum method check but usually it'll let out the ghost with larger leaks. I thoroughly soaked just about everything in WD40 (I live by the ocean, so I wasn't hesitant lol). I got it to idle right around 1100 now, I could go lower but it seems unnecessary.

I didn't clean out the gas tank, I just stuck a mirror down in with a flashlight and made sure there wasn't anything crazy
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post #4 of 6 (permalink) Old 06-16-2018, 06:12 PM
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I think idle spec is 1050 +-50rpm, any lower and oil pressure can suffer.

edit: You're welcome, just got back from a nice ride, resting my bones.

Spraying something flammable is the best way to find those boot leaks. Water will work too, just gives different signs, steam and stumbling. WD40 doesn't flamm so good anymore. So starting fluid was perfect.

I'd get the seafoam and ride some, it will either clean out or clog up. I always say, nobody escapes a carb clean job. I used to brag that I'd never had my carbs off, then one day a pilot jet was plugged tight.

Put regular gas in it, premium will just cause problems.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf

Last edited by Spockster; 06-16-2018 at 07:23 PM.
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post #5 of 6 (permalink) Old 06-16-2018, 08:59 PM Thread Starter
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Regular gas was a good notion thank you. My other bike is a zx12r and I would have likely subconsciously thrown some in.

I threw some seafoam in and made as many trips around the block as I could before I was worried about any police being suspicious (it's got exhaust work done). They might not care but hey lol.

I think I can use the brakes how they are, they've gotten a little better. I really gotta do something about the front forks in the mean time. Is there a common source of progressive forks online?
Or is there an easy way to check oil level/tip off in them? I took off the screw caps and they were just little brass nipples for them to screw on.
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post #6 of 6 (permalink) Old 06-16-2018, 09:42 PM
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Best bet is to change oil in the forks, then fill it with the correct amount (9" from the top, spring removed).

That oil gets really nasty with condensation build up. I think my '03 had the original fork oil and it stunk like hell. I used ATF.

Early models had the air valve on the forks, when they did away with it, they just used the same cap.

I think progressive springs are still available, probably on ebay too.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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