need suggestions - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 41 (permalink) Old 04-25-2018, 02:00 AM Thread Starter
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need suggestions

Hi all I just got a 94 750 about 3 weeks ago and have been enjoying it very much for about 100 miles now. Today I decided it was time to try highway after taking her around downtown for an hour. All went well till around 60, at that point I saw my rpms jump from 4k to 5k twice I think but no difference in speed. I stopped for gas and saw the temperature was almost a quarter of the way and usually it stays at the second line from cold 20 minute rides usually. On my way home the bike got up to speed about 40 and I let off the throttle and at that very second the rpms jumped from 3.5-4k to 5k as I was engine breaking. This continued for about two more lights when I thought I should pull over. At that time I was coasting at 30mph and the rpms jumped from 3k to about 4.5k repeatedly and the lights started to shut off and on along with the engine sounding like it was stalling or losing power. I pulled in the clutch and the engine picked back up to normal idle kinda but the lights still flashed just not as aggressive hazards would not stay on. I coasted with clutch in till traffic finally went around me letting me pull into a parking lot where I went to 1st and pulled the throttle to get up a hill. Up that hill it sounded like it was stalling the lights shut off entirely only for half seconds comming on, the temperature was about half way all just before a thunder storm came in with lots of wind. so I called for a ride and got it towed home. Was about 80 fahrenheit

Things to mention is the previous owner did a ear shave without a rejet and left only the goats belly it also has a small oil leak by the kick stands drain plug from it being striped which I was replacing next week. I figured it was low oil so I threw in 1qt of oil and then parked it haven't tried to start it yet but I did try once more in that parking lot after 20 minutes and it fired up nice but as soon as I gassed it to first it started to lug and shut off the lights so I parked it again then added that oil.
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post #2 of 41 (permalink) Old 04-25-2018, 08:38 AM
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I don't know how helpful this will be, but thought I should get things started. As far as temperature goes, that sounds like normal operation to me. If you're riding at speed in 80 degree heat for any length of time, the temp is going to come up. Quarter of the range is not extreme at all.

As far as RPMs go, to my way of thinking the Vulcan is an older design, short-stroke motor. This bike likes to rev, and I don't think you're getting the best out of it by lugging it. In some ways this motor has more in common with say, an SV650 than a Harley. I try to keep the RPMs above 3k, and then only when cruising along at a lazy pace. Let that motor spin! Also 5k is not at all extreme, so that alone doesn't indicate any kind of problem. It's difficult to get a feel for what the problem is. . . .

Now, I was trying to get an idea if the clutch was slipping or if you are having fueling issues or what, then there's this unknown of oil level. Did you actually check your oil level (bike on center-stand, engine off--oil should at the top line in the sight glass behind the shifter)? Having too much oil is not good either, so you want to be sure you're helping the situation instead of making it worse. . . .

If the bike hasn't been ridden much recently, you might be having some issues with fueling. It sounds like the bike runs well enough most of the time, so chances are a fuel additive like Seafoam or Berrymans B12 Chemtool (my personal favorite), might help things. Is the bike sputtering and bucking? Or is it more an issue of not transmitting the power of the engine to the wheels?

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post #3 of 41 (permalink) Old 04-25-2018, 09:18 AM Thread Starter
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I usually shift at 4k-4.5k and coast at 3k its never had a problem like this till now. As a new rider 5k starts to feel uncomfortable I was going to try the sea foam today see what happened. Only difference ive made is I used chevron gas instead of the cheap brand around town for about half a tank.
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post #4 of 41 (permalink) Old 04-25-2018, 09:51 AM
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What brand and weight of oil are you using? I get the impression maybe the clutch is slipping sometimes. ???

Check the connections at the battery, but the flashing lights make me think the ign. switch needs attention.

With the earshave, check to see where they've placed the carb vents. Wind on the vents can cause erratic performance.

Normal temp is usually at the mid-point of the temp gauge. (needle pointing straight up/forward)

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post #5 of 41 (permalink) Old 04-25-2018, 10:20 AM Thread Starter
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I just checked the battery both bolts where slightly loose and then I think the oil was also low... I put it on the stand and its past full but if I run it a bubble starts to push the oil level down is that normal? With that 1qt I added laat night it seams to stop almost half way it was the only oil I found was a yellow bottle said t4 motorcycle 10w-40 synthetic. I just ordered the filter oil cap for the side drain as soon as it gets here ill try flushing it and filling it properly but so far it seams to run fine
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post #6 of 41 (permalink) Old 04-25-2018, 10:28 AM
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So weird.
Is the throttle cable sawing its way through part of the electrical harness? I've never heard of throttle adjustments being the trigger for brownouts.

Ditto on cleaning the ignition switch, though that doesn't really explain the jumps in RPM, it could easily cause all of the other problems.

Check your battery terminal connections and grounds.
Check for a bad fan relay.
Check your oil level.
Check your oil screen and filter for chunks of clutch material

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post #7 of 41 (permalink) Old 04-25-2018, 10:31 AM Thread Starter
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This is the oil when running this morning after I added that 1st last night. I didnt realize the bike had to be running for the sight glass to move.
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post #8 of 41 (permalink) Old 04-25-2018, 10:36 AM Thread Starter
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Throttle cable looks fine I never noticed but it releases kinda slow and makes a click at the very bottom when released. Ill get back to you guys once I check the screen and change the oil in a few days the cap ships in1-3 days.
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post #9 of 41 (permalink) Old 04-25-2018, 11:12 AM
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Just to be clear, you only check the oil level in the window with the bike OFF, (preferably warm) and on the centerstand (or held up straight). There should be the the tinyest bit of a bubble at the very top of the glass.

As the tachometer is electric, I'd check EVERY electrical connection you can, including the ones in the headlight bucket, the fuses, the coils, and the ignition switch. Look for worn areas on the wiring harness under and around the tank.
(It's been suggested you only use the ignition key by itself and not have it on a key ring with other keys)
Carb or fuel problems would not effect the lights, so it does sound like an electrical issue.
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post #10 of 41 (permalink) Old 04-25-2018, 01:03 PM
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My opinion is that this is probably a little more bike than a new rider wants or needs. I know from watching my son on the 454 that it takes a while to get the confidence you need. Of course we've got sand and debris all over our roads now, which certainly doesn't help him any, but that shouldn't be a problem where you're at.

If your battery cables were loose on the battery that could have been your problem right there. Chances are you could be running your battery down if you're doing a lot of idling, and not spinning the motor especially with loose battery connections. Lights dimming and tach acting up seems consistent with that to me. . . .

Looks to me like you probably overfilled the oil, too. Generally, when it's running you're not going to see oil in that window except maybe right at the bottom. Chances are there's not enough extra to cause any harm.

You're getting lots of good advice from everybody. Just give it some time and you'll get used to it. I love mine!

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