[Marcusantonius]

Hi I have a 95 vulcan en500A and recently while riding I revved up through a couple of gears and then slowed down at a stop light. As the bike revved down I hear a clunking noise that sounded like it came from the head of the engine. When I got home I tried to get the bike to do it again and I couldn't get it to. Since then it has done it on occasion. It seems like it only does it when I decelerate and on the down side of a Rev. Any clue what it could be?

 

[Kawasakian]

It may be time to get your valves adjusted. The reason you don't hear it after revving is that it may be coollig down enough to not make any size. What you don't want is the valve closing up on you, it could damage the came. Get the valves check, or do it yourself. That's where I'd start.

 

[Marcusantonius]

It may be time to get your valves adjusted. The reason you don't hear it after revving is that it may be coollig down enough to not make any size. What you don't want is the valve closing up on you, it could damage the came. Get the valves check, or do it yourself. That's where I'd start.

How do I check the valves to make sure they're good? Also the bike is straight piped so there isn't much back pressure. I've heard that it can cause damage to the valves. Is this true? Because everything I have read online is divided. One guys says it's not bad for them and another says it is.

 

[Kawasakian]

Oh yeah, straight pipes have to have the carbs jetted for that. You can burn the exhaust valves. Either bring it to a dealer, or get the Factory Manual. You can find them online for free in .pdf form. Not allowed to post links. Get a Kawasaki Factory Service Manual, not some Hayes, or Chilton. If you don't know how to adjust valves, best if you bring it to someone, or really commit to it. Get a proper muffler for that bike. I'm sure there are a ton of them on EBAY, and they made so many of those bikes, they can had cheaply. You'll get more power too, as you lose a lot of mid-range with straight pipes, especially if the carbs are set up for it, carbs of fuel injected, it has to be set up for that.

 

[WFO-KZ]

Yes, a straight pipe will burn exhaust valves. It may take thousands of miles or even tens of thousands of miles but lack of back pressure allows valves to burn.

I am not too familiar with your bike, but if it has a decompressor, then that could be the source of your clunking noise.

I agree, get the factory service manual so you can learn how to check and adjust your valves and study how the decompressor functions (if so equipped).

 

[9094]

Any chance it's the chain? Since it happens when decelerating only. possibly some frozen links,,,

 

[Kawasakian]

On deceleration, usually it is a hydro carbon backfire, which is unburnt fuel exploding in the tail pipe, indicative of a lean condition, and possibly burnt valves. A compression test could help you tell where the valves are. I sincerely doubt that it would be the chain, you should lube your chain after every ride, the sprockets last much longer.

 

[novice67l]

Hi I have a 95 vulcan en500A and recently while riding I revved up through a couple of gears and then slowed down at a stop light. As the bike revved down I hear a clunking noise that sounded like it came from the head of the engine. When I got home I tried to get the bike to do it again and I couldn't get it to. Since then it has done it on occasion. It seems like it only does it when I decelerate and on the down side of a Rev. Any clue what it could be?

I would suspect the cam chain tensioner first. They will slip and grip, causing the plastic chain guide to bounce and the chain to go slack then tight. Noise comes and goes with no apparent pattern.
Excessive valve clearance noise is usually a constant, may get louder as the engine get hotter. The do need to be checked regularly for sure.

 

[Kawasakian]

First thing you should do is tune your bike up. Put some mufflers on it, in case it isn't too late.