pulsing engine sound at highway speeds

[molly]

Hi everyone. First post here. Bought a GZ 250 on 6-15-07....2006 model, but new. (still on the showroom floor) I LOVE the bike! Rode it yesterday and again today, about 20 miles each time. I am a very new rider, so today was alot more relaxed than yesterday. Anyhow, during the ride today i noticed a pulsing sound that came from the engine when i was up to 40-55 mph. There was NO power loss or surging of the engine itself. Everything felt fine...just this strangely faint pulsating sound. Will get the bike checked by dealer, as it has a warranty, but was wondering if anyone has had this experience with their bikes. Any ideas or suggestions will be greatly appreciated.

[jonathan180iq]

I think I've experienced the same thing. It seems to just be a product of the twin dome combustion chamber. Unless there are some negative side effects, I wouldn't worry about it.

[molly]

Thank you so much Jonathan! You've taken a load off of my mind, and I appreciate your taking the time to help me. I LOVE my GZ250, and want to be sure she is "healthy". Thanks! I have only had the bike 3 days, and I have had a real blast on it!

[Easy Rider]

Originally Posted by molly

Thank you so much Jonathan! You've taken a load off of my mind, and I appreciate your taking the time to help me. I LOVE my GZ250, and want to be sure she is "healthy". Thanks! I have only had the bike 3 days, and I have had a real blast on it!

Welcome to the family!
Agree with the others that this is probably normal. Almost all bikes have a "buzz point" somewhere in the rpm range. Unless it gets louder, I'd mention it to the dealer at the 600 mile service.

I'm not into a lot of modifications on bikes I own, at least not on the engine, as I think one often ends up worse off than they started out stock. Got a small windshield, foam grip covers, backrest/rack and side bags. I sent the engine guard back as it looked pretty useless to me.

There is, however, one mod that I did do. Changing the front sprocket to a 16 tooth (from stock 15) REALLY changes the character of the bike. The "feel" is entirely different......and better. Now I can make a left turn from a stop without shifting into 2nd in the middle of the turn! Can cruise around town at 40 in 4th gear with no strain.

If you like your bike now, I promise you will like it even more if you change that sprocket!
Part cost about $18. Labor cost about $35. If you have it done, be sure to check the adjustment of the back brake B-4 you ride it away. The change loosens it a bit and my shop failed to adjust it back.

[birdmove]

I've owned about 20 differerent motorcycles over 45 years of riding, and I've heard these "pulsing" noises on many of them at certain speeds or rpms. I think in some cases its a noise from the chain reveberating off guard rails and such. Never had any related problems.
I've had several front wheel drive cars that, if we rolled down the windows, made a noise exactly like a helocopter was hovering just above us. It had to do with the cv joints, and noise reveberating. None of these cars ever had any cv joint problems.

jon

[Gadzooks Mike]

Since we're into pulsing bikes, has anyone noticed that at a certain RPM, the bike actually almost bounces up and down? It's like riding a trotting horse. I'm guessing that it's sypmathetic vibration caused by the single-cylinder engine that just builds up. I can hit it pretty consistantly at around 40mph in 4th gear with the 16T sprocket. All I have to do is back off the throttle or go up just a hair and it goes away.

Ride 'em cowboy! Yeeehawwwwww!

[Easy Rider]

Originally Posted by Gadzooks Mike

Since we're into pulsing bikes, has anyone noticed that at a certain RPM, the bike actually almost bounces up and down?

Well, Shut My Mouth ! :??:

I thought that was just the road I was riding on.
Amazing.
Gotta go out for a test ride.
Bye.

[molly]

Thanks, everyone, for all the nice knowledgable replies. Will call the dealer tomorrow to double check that all is well, but you have all greatly eased my mind. Everyone here is so nice! I am very glad i found this site, and glad I have my GZ now too! DH and i are actually riding together, WITHOUT me being a "passenger" on his Harley Softail. I also have a 1999 Honda Shadow ACE vt750 to "graduate" to when the time comes, as well as a couple of dirt bikes, so our next investment needs to be a large garage! I have been "bit" by the motorcycle bug! LOL! Thanks all for helping me out. Look forward to being here for a long time to come.

[molly]

Had the bike checked out on Saturday. All is well.......Thanks for all your help everyone!

[Badbob]

I made this sound go away on my GZ250 buy carefully adjustment of the chain tension aligning the sprockets with a gauge that easily lets me see if the chain and sprockets are aligned properly. I don't us the marks any more. Mine were not even close.

After thousands of miles of riding sound has not returned.

My theory is (No I can't prove it) that the noise was a combination of two things. The fact that sprockets are not perfectly round causing the chain to be tighter in some spots that others and the sprockets not being aligned properly. Its not even my theory really. I ran across this some where else but I can't remember where.