2006 f650gs date of mfg 11/05

2006 f650gs engine noise

Hello all!

I recently purchased a used 2006 F650GS (date of mfg 11/05) from the original owner with 9,800 miles. I've now noticed and engine noise/knock. It could have been there previously as my test ride was very short. This occurs at 2500 through 3500 rpm, under load, only. I can't seem to replicate the noise while on the center stand. It's difficult to tell where the noise originates. I've used a mechanics stethoscope to no avail. The engine seems to run flawlessly other than that noise. It has good power and accelerates well even through that rpm range.

The previous owner said he did regular oil changes as they were free to the original owner. The oil level is full and the oil appears clean. The bike seems to have had some regular maintenance as the chain and sprockets are newer. But he did say it's never had the valves adjusted because it didn't need it until 12k miles, which a Haynes manual confirms. I put in some octane booster to see if maybe I got some bad gas, but no change since adding. Any comments or suggestions would be appreciated.

Thanks.

Welcome to the forum!

Could it be an echo from the air-box (intake) that you are hearing? Cruising along with everything sounding great, in a gear higher than you should be in, rolling the throttle on hard would test this possibility. You could almost play a trumpet like tune as the engine “eats” more air than it can use. It could also sound like a long fart.

If it’s of a higher pitch, try as high an octane gas as you can find.

Let us know how you make out.

Good luck.

Gary

Omega Man said:

Welcome to the forum!

Could it be an echo from the air-box (intake) that you are hearing? Cruising along with everything sounding great, in a gear higher than you should be in, rolling the throttle on hard would test this possibility. You could almost play a trumpet like tune as the engine “eats” more air than it can use. It could also sound like a long fart.

If it’s of a higher pitch, try as high an octane gas as you can find.

Let us know how you make out.

Good luck.

Gary

Click to expand...

While I briefly considered and air box/ filter issue, I haven't explored it. The noise is definitely in the low to low-mid frequency range. More of a fast knock-knock-knock and ONLY in the noted rpm range, any gear, any speed, while accelerating. And farts are always funny. Maybe I'll remove the oil tank and air box plastics/covers and take it for another ride.

2500 rpm is lugging that motor. Power on at 3500 or 4000 or more.

I agree with Paul. My wife has had F650s since ‘03. Our last F models were ‘07s. We each currently ride 2016 G models. To the uninitiated, the Rotax 650 often sounds like it’s eating its young. We’ve been all over the country on those things. They are GREAT motorcycles!

Ed_Jorgensen said:

I agree with Paul. My wife has had F650s since ‘03. Our last F models were ‘07s. We each currently ride 2016 G models. To the uninitiated, the Rotax 650 often sounds like it’s eating its young. We’ve been all over the country on those things. They are GREAT motorcycles!

Click to expand...

I laughed out loud at "eating its young"..

So far, I've got "farts" and "eating its young".

While I've ridden motorcycles most of my life, my only experience with a 650 thumper was a klr. With the Rotax, I am, agreeably, uninitiated. This could be a completely normal sound. It would be nice if someone local (Colorado Springs, CO) could listen/ride and/or I could ride their's.

I did pull the plastics off yesterday. I didn't realize the air box is right there. I took it for a short ride as it was starting to rain. I didn't notice anything different in the sound to discern it's origination. I'm going to try to get a sound recording or video. Can I upload those to this thread?

I'd ask your local club if anyone has experience or look in the anonymous book too!

You can upload the video to Youtube or Vimeo and share

Air box noise confirmed

Omega Man said:

Welcome to the forum!

Could it be an echo from the air-box (intake) that you are hearing? Cruising along with everything sounding great, in a gear higher than you should be in, rolling the throttle on hard would test this possibility. You could almost play a trumpet like tune as the engine “eats” more air than it can use. It could also sound like a long fart.

If it’s of a higher pitch, try as high an octane gas as you can find.

Let us know how you make out.

Good luck.

Gary

Click to expand...

Gary/Omega Man,

Excellent diagnosis! The air box "echo" is what I'm hearing. I removed all the plastics from the around the air box and sure enough, a cruise with the stethoscope confirmed the origination of this most unusual (to me) sound. It appears that the throttle body/air intake points straight up and the air reverberates throughout the air box under load in this rpm range. Who new? Gary did! What made you think this was the noise I was hearing?

Anyway, good call and I thank everyone for their input.

xstevexf650gs said:

Gary/Omega Man,

Excellent diagnosis! The air box "echo" is what I'm hearing. I removed all the plastics from the around the air box and sure enough, a cruise with the stethoscope confirmed the origination of this most unusual (to me) sound. It appears that the throttle body/air intake points straight up and the air reverberates throughout the air box under load in this rpm range. Who new? Gary did! What made you think this was the noise I was hearing?

Anyway, good call and I thank everyone for their input.

Click to expand...

Glad it worked out for you

Back in the day we could always hear basically what you were describing when we “kicked in the quad” or- 4bbl carburetor.
Through the years it seems air intake noises would sometimes over shadow exhaust noise, something luxury car owners complained about.
Also, a poorly running vehicle that bogged down or wouldn’t accelerate when the throttle increased really exaggerated the noise.
Happy riding!
OM