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Discussion Starter #1
I have a 2001 Kawasaki Vulcan 750 that has a popping sound when decelerating. It didn't do this until after I had my accident. Now it does it every time I ride. It isn't really an issue from what I can tell, as most people have said it won't hurt anything. However, it's pretty annoying and bothersome for me and I'm sure cars around me don't like it. I planned to take it in to have it looked over anyway during the winter to make sure nothing is messed up on it from the accident, but I figured I would ask some people on here for their ideas or suggestions. I am pretty new to riding and I really don't know much about repairing bikes AT ALL. I'm a true newbie!
 

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Crap, I WAS in 5th gear.
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Exhaust popping is caused by a lean condition in the exhaust. Search for "marble" in this forum, and check all your carb boots and vacuum lines- something might have been knocked loose is your accident.
 

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If it weren't for the "accident" I would say it is caused by the air injection system if it still has one. Those things inject air into the exhaust, causing unburned fuel in the exhaust to ignite, making weird noises, and causing the exhaust to overheat. Need more details on the accident. I have read a number of posts on different forums about bikes not running right after just falling over. That is possible, but should be very temporary. Gas runs out of the carbs, oil can run out the crankcase vent and into the airbox, etc. If yours has been doing this for some time after the accident, then it is very likely that some part of the intake or exhaust system has been damaged.
 

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Discussion Starter #5
Accident? What hit the ground?
If it weren't for the "accident" I would say it is caused by the air injection system if it still has one. Those things inject air into the exhaust, causing unburned fuel in the exhaust to ignite, making weird noises, and causing the exhaust to overheat. Need more details on the accident. I have read a number of posts on different forums about bikes not running right after just falling over. That is possible, but should be very temporary. Gas runs out of the carbs, oil can run out the crankcase vent and into the airbox, etc. If yours has been doing this for some time after the accident, then it is very likely that some part of the intake or exhaust system has been damaged.
I was going about 35mph on the interstate and a car cut the person in front of me off and I made the mistake of only grabbing the front brake and way too hard, so i lost control of the bike (I had only been riding for about a month at the time) and the bike and myself only slid about 10-15 ft. I didn't hit any other vehicles. It has been doing the popping since then on deceleration. The only other issue I have had since the accident is that when the bike is first started, it has a clanking sound coming from the engine and then after the bike warms up, it's gone. The handlebars got a little bent, but thankfully the forks themselves didn't get bent so the bike is still very much ride-able. I actually rode 70 miles this past Saturday with no issues, just the popping and clanking until it warms up, then everything was fine. It was a rookie mistake and I have been very careful since then.
 

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Didn't really answer my question. (what hit the ground).


If you have been riding the bike for some time with no "popping" and it began after it fell over, I still would suspect the exhaust on whatever side touched down.

That said. From what I know...ALL stock Vulcans pop on decceleration. Why yours didn't before is more of a mystery to me than why it does now.
 

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Discussion Starter #7
Didn't really answer my question. (what hit the ground).


If you have been riding the bike for some time with no "popping" and it began after it fell over, I still would suspect the exhaust on whatever side touched down.

That said. From what I know...ALL stock Vulcans pop on decceleration. Why yours didn't before is more of a mystery to me than why it does now.
sorry. When it fell, the only stuff that really hit the ground was on the left side...so the shifter got scraped up a bit, as did some of the plastic and turn signals, and i guess the left side pipes would have had to have hit the ground as well.
 

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Hopefully the shifter shaft is still ok. When dropped on the left side, many times something breaks off the internal shift shaft, allowing it to have way to much in and out play, like over an inch.

Check the left side exhaust for any leaks, from the head to the tip of the muffler.

You didn't mention the "clanking" sound before, I doubt it has anything to do with the "popping". When the bike went down, did it continue to run for a few seconds? When you picked it up and restarted it, did the oil pressure light stay on very long? Many bikes have a serious design problem with the lubrication system, so when the bike is dropped, even if it is picked up and allowed to sit for a few minutes in the upright position, it will still run for as much as 30 seconds without oil pressure. I have never dropped a bike, but I've read about this on many different forums. For some reason, when the bike is on it's side, the oil pump loses it's prime, and it takes some time for it to start pumping again. It does not do this even after changing the oil, only if dropped or layed down in the horizontal position. I wonder if it ran long enough without oil to damage the engine.
 

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Discussion Starter #9
as soon as I dropped the bike, it shut off...because I had the bike in 1st gear and didn't obviously pull in the clutch or anything, so it shut off automatically, which is why it didn't slide that far. The bike didn't start back up right away once I got it upright again, it took a couple minutes to start, but finally got it going and the oil pressure light didn't stay on any longer than normal.
 

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as soon as I dropped the bike, it shut off...because I had the bike in 1st gear and didn't obviously pull in the clutch or anything, so it shut off automatically, which is why it didn't slide that far. The bike didn't start back up right away once I got it upright again, it took a couple minutes to start, but finally got it going and the oil pressure light didn't stay on any longer than normal.
Great. Maybe the VN750 is one of those bikes that doesn't happen too. Then that probably rules out any internal engine damage. No part of the engine would contact the ground when you dropped it. It doesn't stick out far enough. But the left side exhaust is bolted solidly to the rear cylinder, and an impact to the exhaust could be transferred to the engine. Again check for any exhaust leaks. The popping, if it is more noticeable than before, is caused by something that changed. Was there any damage to the choke lever or cable?


The "clanking" sound that goes away after the engine warms up sounds suspiciously like the ACCTs have failed. That could have been caused by the force of an impact, even without touching the tensioners, if they were almost worn out anyway. Go to the "Vulcan Verses" and look up the "Grambo Trick" and try that. If that stops the noise, that pinpoints the problem. But even if it works, it will most likely be temporary. If that is it, then manual tensioners will fix the problem.
 

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Discussion Starter #11
I really hope it's not the tensioners causing the clanking because if so, that sucks. I just had them replaced maybe 3 weeks before the accident. I will try all of the things mentioned and let you know what the outcome is. I might just end up taking it in and having it looked at during the winter, because I really don't work on bikes, so I would be afraid of screwing something up even worse.
 

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Just out of curiosity - when you say "clanking", I am assuming it sounds like it's coming from inside the motor, and that's why you're asking about the tensioners and such, right?

I ask because I have seen other posts where a clanking was caused by one of the heat guards on the exhaust being loose - just wanted to rule out that possibility, especially considering the fact that it didn't start til after the bike was dropped.


AZ Kev
 

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Discussion Starter #13
Just out of curiosity - when you say "clanking", I am assuming it sounds like it's coming from inside the motor, and that's why you're asking about the tensioners and such, right?

I ask because I have seen other posts where a clanking was caused by one of the heat guards on the exhaust being loose - just wanted to rule out that possibility, especially considering the fact that it didn't start til after the bike was dropped.


AZ Kev
I can't really tell where it's coming from, it might be coming from the heat guards, I don't know. It's been raining here so the bike has been covered up. It should be decent weather this weekend so I may look at it then. Thanks everyone for your suggestions. I really appreciate it.
 

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If you just replaced the tensioners with oem Kawasaki parts, like I did the first time, well, mine lasted about 10,000 miles till they were so badly worn the plunger would no longer stay in place. I took them apart, and the wear to the threads that allow the plunger to extend was obvious. No way to repair them, unless you convert them to manual. I decided to do it right and bought professionally made manual tensioners. Not only have I not had any more problems in over 40,000 miles, but the TOC tensioners are big beefy very well made items, not flimsy cast junk like oem. If you just put new springs on worn out tensioners, then they are still bad.

One other thing I just thought of, if you have a CA model, and it still has the EVAP cannister on it, that is most likely the cause of the popping. When the bike went down, the fuel would have run out through the tank vent, and filled up that cannister, which will cause all kinds of issues, including some I have never figured out. Best to get rid of ALL emissions crap.
 

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Discussion Starter #15
It's not a CA model, so none of that stuff applies. Honestly, Ive pretty much given up on this issue now because i'm pretty used to it now and it doesn't do any damage to the bike from what I can tell.
 

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Discussion Starter #16 (Edited)
alright, an update on this issue. I tried the "grambo trick" for the tensioners on friday afternoon when I got home from work and the clanking noise went away, but i haven't ridden it for any length of time, it just was sitting idle when I tested it. I ran it first to see if it was clanking and it was...so I turned it off and did the trick and started the bike up again and the clanking was gone. :notworthy I am not worthy of all of your knowledge!

also, for the popping on Deceleration issue, I turned the fuel/air mixture screws all the way in on the carbs and then out 2 1/2 turns and next time I ride will see if this issue is resolved as well. I didn't really count how many turns out they were already, but i did notice one carb was out a lot farther than the other, so I just reset both to 2 1/2 turns.

Thanks for the suggestions on this issue and hopefully it is fixed now. Being as I dropped the bike on the same side that the ACCT is located, I guess it must have knocked it loose or something.
 
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