Sputters between 2K and 5K RPMs - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 21 (permalink) Old 01-14-2007, 03:40 PM Thread Starter
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Sputters between 2K and 5K RPMs

The odd part is it runs fine cold. Once she warms up I have all kinds of problems between 2K and 5K RPMs. The hotter the bike the worse it gets. I'm not talking overheating type temperatures. Just normal running temp.. stalls and pops.. tac goes jumping up and down. If I get it over 5K, runs just fine. Below 2K is fine. Idle is smooth.

I'm assuming I've got a mid-range jet clogged but why the change with temp? I can pull over and sit for awhile and it'll run fine again for a bit..

Any ideas?
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post #2 of 21 (permalink) Old 01-14-2007, 04:22 PM
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Check the hose in the right ear.. If there isn't one there and you still have the stock air filters, it needs to be routed through the little grooves. If there is one there, make sure it isn't bottomed out against the case. Cutting the tip at 45 degree prevents that happening again.
When you are running you need spark, fuel and air. If the air is cut off (also check for the hose being kinked or pinched) the bike will sputter since it is actually gasping for air.

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post #3 of 21 (permalink) Old 01-15-2007, 02:17 AM Thread Starter
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Checked. Air filters are fine as well.
There seemed to be a lot of oil on the carbs. Not sure if that's a clue. How would oil get there? Actually I'm not 100% sure it was even oil. I cleaned up everything and will monitor it.
Bike could use an oil change but if it's leaking I don't want to waste my time/money.
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post #4 of 21 (permalink) Old 01-16-2007, 09:46 PM
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The oil in the filters is there to catch the dirt that comes in. The oil is there on purpose and is not an oil leak or a bad thing. When you clean the air filters you will get to re oil them as well.
If the vent hose is kinked or plugged, it can cause the symptoms you are describing. The change in performance from cold to warm can be caused by the heat causing the hose to expand or elongate and cause the pinch off/plugging of the hose. Follow Dianna's advice and check the hose and let us know so that if the vent hose is the problem, we know it's solved. If not, there are some other avenues you might try such as Sea Foam.

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post #5 of 21 (permalink) Old 01-16-2007, 11:16 PM Thread Starter
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I've been running Seafoam for a couple weeks already. After checking everything else I went to pulled the carbs. The brass pieces that the float pins hold onto had a lot of crud on them. I gave each jet several blasts. Bike seems to be running okay but I have to reset the idle and maybe the air mix screws. This is complicated by the fact my idle adjust bolt snapped a month ago.
I'm sure I'll have it under control soon.
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post #6 of 21 (permalink) Old 01-17-2007, 12:33 AM
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well i wish ya luck. if you keep having carb trouble, you may wanna get an ebay replacement, although it looks like you have made it into the home strech. one thing that i suggest that doesnt look like you have done is the seafoam soak. its better then the blasts you were giving.

over a weekend or so, drain the bowls, fill with a 100% seafoam, and run for just a few seconds if she will start, if not just crank for a few to get the seafoam pulled into the jets. let it sit over night. this will clear out any and all gunk left over since it sounds like you had quite a bit, since the pins and innards are the last thing to gunk up. afterwards, drain and fill back with gas, and start like normal (may take a few cranks)

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post #7 of 21 (permalink) Old 01-17-2007, 04:42 AM
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Quote:
Originally Posted by Sky Rider View Post
The oil in the filters is there to catch the dirt that comes in. The oil is there on purpose and is not an oil leak or a bad thing. When you clean the air filters you will get to re oil them as well.
Just wanted to point out that he mentions oil (?) on the carbs, not the filters.

And, if ya do get things running good and are happy with how the carbs are working, replacing the idle screw is an option.
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post #8 of 21 (permalink) Old 01-17-2007, 07:44 PM
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I really wasn't too clear on where he meant the oil was coming from. One never knows exactly how "new" one is to mechanican.
If it's on the carbs, it could be coming from the valve cover gasket leaking a bit or it could be someone did the WD 40 test and just left the mess.
Either way, it sounds as if Bean is well on the way to fixing his ride.

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post #9 of 21 (permalink) Old 01-23-2007, 11:42 AM Thread Starter
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Okay so here's the latest..
As I mentioned, Monday last week, I pulled the carbs and gave them a good cleaning.

Once I had the idle set the bike ran great. I was very happy because I had planned on riding to Vegas that weekend. The following couple days I found and fixed a problem with a throttle cable. Didn't do any long/hard riding (just my commute to work, about 7 miles each way), but as far as I could tell she was running fine.

Thursday I changed the oil and replaced the oil filter. Unknowingly at the time I had overfilled the oil.

Friday I start having the same problems again on the way to out meeting place before heading out to Vegas. Bike ran fine above 5K RPMs. Considering it'd be freeway riding the whole trip, and I already had everything booked/paid for.. I continued with the trip.

Everything went as expected. As long as I kept the RPMs above 5K and below 7K (which is were she prefers to run anyway), it was fine. Other then being cold at the end the ride was quite nice until I actually got there and had to deal with traffic lights and such.
Along the way I discovered I had overfilled the oil. My parking lot at home is slanted so the bike is not level which adds some guess work to things like oil changes.
This would explain the oil in and around the carbs I mentioned earlier (although some of that may indeed have been from a WD-40 job

So I drained the oil down to Low on the sight glass. Dumped some generic carb "treatment" in the tank (couldn't find SeaFoam anywhere in Vegas). I might have been in my head but there seemed to be some improvement but the bike was still having the same problems. Sunday I road home and noticed I could get above 7K RPMs (I never had the chance to safely test the limit). I kept it around 80mph and got home fine. I then dumped half a can of SeaFoam in the tank.

I've since made one round trip to work and the problems are the same. Fortunately I bought a dry-cell battery (as recommended here) which has made starting the bike as easy as pressing the button, so stalling at lights isn't so nerve wracking when it happens.

Sorry this post is so long. I thought if I wrote it all out someone might pick up on a clue. I believe the oil change had something to do with it. This originally started after a day of maintenance, which included an oil change but also a bunch of other stuff which confused the situation (did too much stuff at once, big no no). I'm quite sure I had overfilled that time as well.
However, with the oil now at Low, and having traveled 300 miles I would have thought any oil left in the carbs would have worked it's way out by now.
Would oil in the carbs even be a problem to begin with? Perhaps it's something completely different that I'm missing..
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post #10 of 21 (permalink) Old 01-23-2007, 12:22 PM Thread Starter
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Sorry to double post. I just realized my fuel lines to my carbs to the petcock are backwards. The rear carb's line should go to th front connection on tghe petcock etc. Does this really matter at all? The manual says this is to keep the hoses from flexing or something to that effect. I've already cut mine down so that they're okay as they are. I'm just not sure if it'd effect anything like that.

I've never synced my carbs and have had them off three times. So now I'm looking into that as a possible issue.. Much reading to do..
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