Knocking sound at idle?

[GS750cafe]

Thanks Chuck. I'll give the clutch springs a look. There's no harm in pulling the basket even if the springs are ok, right?

[tkent02]

Thanks Chuck. I'll give the clutch springs a look. There's no harm in pulling the basket even if the springs are ok, right?

If it's clutch related, the sound will go away or at least change when you pull in the clutch lever. Does it?

I hear two sounds, a dull thump every rotation that you can hear in the first seconds of the video, and a tick tick every few rotations that can be heard when the camera moves farther back, and from the right side. The dull thump could be due to poor carb synch, cams walking, even and exhaust or intake leak, not sure what else. Doesn't sound too serious, it's a GS. Have you vacuum synched the carbs? Are there any exhaust or intake leaks? The tick tick I believe has something to do with the cam chain, as it timing of the ticks is once every several rotations, about how often the chain goes around the sprockets. My 650 does this, a friend's 750 does this, I have heard it on a few others. Also doesn't sound too serious, none of these bikes have had any failures yet. We have pulled the valve cover on the 750 and checked for a bad link going around, couldn't find anything. Ride it and smile.

Just listened again, by the way the acceleration lagged when you blipped the throttle at the end, the carbs are out of synch, quite a bit.

[waterman]

Like tick, tick............................tick, tick................................tick, tick?
Quite a long interval between each pairs of ticks?

If it's clutch related, the sound will go away or at least change when you pull in the clutch lever. Does it?

The tick tick I believe has something to do with the cam chain, as it timing of the ticks is once every several rotations, about how often the chain goes around the sprockets. My 650 does this, a friend's 750 does this, I have heard it on a few others. Also doesn't sound too serious, none of these bikes have had any failures yet. We have pulled the valve cover on the 750 and checked for a bad link going around, couldn't find anything. Ride it and smile.

Best description yet of my tick problem in my 650. I drive a 2 miles down my road, stop at a signal and bike will tick tick.....tick tick.... at idle. Drive another mile and usually gone. Not everytime but often. Have to agree, it sounds like cam chain related. Also will concur with Ride it and Smile.

[chuck hahn]

The spring rattle in the clutch SOMETIMES will go away if you pull in the clutch but not always. Mine didnt on my 78 750E and i was thinking my engine was toast so Rustybronco decided to come over and have a look and he discovered that the springs were loose where as i didnt think they were all that bad. So moral of the story is check evrything visually and thoroughly yourself. Even if you pull in the clutch lever the basket is still spinning so it will still clatter. And also remember that bad valve adjustment coupled with bad carb syncing will make the engine rattle quite loudly also. There may be a combination of things causing these symptoms.

[raistian77]

Yep, sounds like "cam walk".

Rather than "revving" the engine, increase speed slowly. If the noise goes away between 12-1500, it's almost guaranteed to be cam walk.

More annoying than destructive, many of us just live with it, although a few have found cures.

.

nah, sounds like the little gremlins that make engine go are bored and rapping on the casing. I found if you rev it up it makes the little buggers work and they have no idle (har) time to smack random stuff with their hammers.

[sschering]

My 79 GS100 sounds like a box of rocks when it's cold and I let the idle drop below 1000 rpm.. I still need to do valves and a vac sync.
Looks like I'll add check the clutch hub nut to the list.

[GS750cafe]

Wow! Thanks for all the input guys. I have not synced the carbs yet. I need to rejet as well. There is most definitely an exhaust leak that I'll get to. I was thinking of tweaking the exhaust a bit first - maybe shortening and then adding some baffles to reduce noise (is this a bad idea?). Then I'd get into the carbs. I've had a 1991 gsxr 750 that had some noisy valves, but was such a work horse that all I did was ride it and smile! The interesting thing with this ticking is that the engine has got to be really warm before I start hearing it...

[chuck hahn]

Scott..the clutch basket MAY be fine.. the combination of valves needing adjusted and the carbs being out of sync will produce some really harsh noises. Also check the timing while doing the tune ups!! In my opinion..and mine only.. I feel that the time it takes to pull the basket and check the springs its well worth removing that worry from the equation. You can pull everything and have it back together in a matter of an hour or so and a 12 dollar gasket. These bikes are awesome, but i have learned that they need to be tuned in well or they will make funny noises..and thats the beauty of them. They will definitely let you know when you have lapsed on the maintenance by making noises.

[49er]

Wow! Thanks for all the input guys. I have not synced the carbs yet. I need to rejet as well. There is most definitely an exhaust leak that I'll get to. I was thinking of tweaking the exhaust a bit first - maybe shortening and then adding some baffles to reduce noise (is this a bad idea?). Then I'd get into the carbs. I've had a 1991 gsxr 750 that had some noisy valves, but was such a work horse that all I did was ride it and smile! The interesting thing with this ticking is that the engine has got to be really warm before I start hearing it...

Just listened to your video. That's cam walk.

If you want a fix, visit Basecliff's site for the details.

If you can live with the noise, just sync the carbs and ride it.

[cyclefvr2]

im going to say check the timing chain adjuster,im sure at 12k or so it will need set again
if carbs need set do that as well, its not hard on those carbs, just follow the book,
1 of the BIGEST problems is crappy fuel!, go with the highest octain at the pumps, and a good station, this alone is going to get rid of a ton of clunkity clunks
i dont think its cam rattle, though

[tkent02]

im going to say check the timing chain adjuster,im sure at 12k or so it will need set again
if carbs need set do that as well, its not hard on those carbs, just follow the book,
1 of the BIGEST problems is crappy fuel!, go with the highest octain at the pumps, and a good station, this alone is going to get rid of a ton of clunkity clunks
i dont think its cam rattle, though

What a crock of B.S.
Cam chain adjusters don't need reset, they either work or they don't.
Use low grade gas, it's a low compression engine.

[1948man]

What a crock of B.S.
Cam chain adjusters don't need reset, they either work or they don't.
Use low grade gas, it's a low compression engine.

Don't be vague and beat around the bush. Just say what's on yer mind.

[chuck hahn]

Tom is basically correct on the cam chain tentioner. They can however get gummed up and stuck in a loosened state. Find the tutorials posted here and clean the tentioner if you so desire. Also remeber that once you get the screw to touch off on the adjustment, to back it off about 1/4 turn and then tighten the jam nut. They are supposed to work on a spring system and if its just locked tight against the rod and jam nutted there it wont float and do its job properly.

[Nessism]

Cam walk on a 12k mile engine? Doubt it.

Since this is a new bike to you I strongly suggest the following: carb sync, rejet for pipe, adjust the valves, pull the cam chain tensioner and make sure it's springing outward as designed. This is all basic maintenance and needs to be done regardless. Build a base with solid maintenance and then worry about things like noises second.

[49er]

Cam walk on a 12k mile engine? Doubt it.

Since this is a new bike to you I strongly suggest the following: carb sync, rejet for pipe, adjust the valves, pull the cam chain tensioner and make sure it's springing outward as designed. This is all basic maintenance and needs to be done regardless. Build a base with solid maintenance and then worry about things like noises second.

Older members who have owned these bikes from new back in the day, reported excessive endfloat clearances on some models, ex the factory.

I have done good research on this problem, and have offered a realitively cheap fix. Believe me, that noise is cam walk, from excessive camshaft endfloat.

Low mileage engines can be afflicted with this problem, especially if whey have spent a lot of time idling while perched on the side stand.