Working with a BUZZ

[79XS11F]

This BUZZ is in deed present even on the main stand when throttle is increased. I do notice that when I put my hand on the clutch cover, stator cover, or timing cover the engine does not produce a lot of vibration. I think the next thing to do is switch out the engine mounts for the ones that came with that engine and see what I got.
The manual says .. worn crank, rod or trany bearings. Anything is possible but I can't see that being the issue because the engine was smooth enough when I got the bike before doing the engine switch outs from stock to the hop up and then back to stock.
Rob

[79XS11F]

Originally posted by chopwatchagot
How are your valve springs? If they are out of spec they could be creating some different harmonics. The inner and outer springs are designed to cancel out each other's vibrations (harmonics) and maybe yours are out of tune.

I will check that as a last possibility and do it in winter. When I pulled the head on this engine to clean things up the valve springs went in exactly as they came out. I actually pull strapped them together to avoid possible mix ups and assure that they went back in the way they came out. I did not check them against spec when they were out because I had not issues at the time.
Rob

[olebiker]

Originally posted by 79XS11F
This BUZZ is in deed present even on the main stand when throttle is increased. I do notice that when I put my hand on the clutch cover, stator cover, or timing cover the engine does not produce a lot of vibration. I think the next thing to do is switch out the engine mounts for the ones that came with that engine and see what I got.
The manual says .. worn crank, rod or trany bearings. Anything is possible but I can't see that being the issue because the engine was smooth enough when I got the bike before doing the engine switch outs from stock to the hop up and then back to stock.
Rob

Sounds like it almost has to be engine mounts. Vibrations are a pita to track down.

[79XS11F]

Well i hope that is the case. Changing out the engine mounts can be done with the engine still in the frame but I will have to prep it as if it's being removed and jack it up within the frame space so I will not do that until we hit a spell of rain
Rob

[mikeb]

My 80 MNS has a buzz that comes and goes but I know what causes it. Started years ago and drove me nuts trying to find it. Turned out to be a crack in the weld where the outside header pipe welds to the muffler. I welded it but it cracked again. I took of the heat shield and wrapped it tightly with muffler tape and put the shield back on. You can't see the tape unless you look up from below. When your riding try putting your heel against the heat shield and see if the buzzing stops. If it does the look for a cracked weld. Stock exhaust is known to crack at that weld.

[79XS11F]

I will check that the next time I use her Mike.
Rob

[Dragon Tamer]

Rob,

I originally had the almost exact same problem with the
Dragon, then after I threw away my four gauge sync tool and went back to my home built tube type and got the carbs synced right, it went away. In the last week or so it has come back again, to the point where the fairing vibrates so loudly that people in cars at intersections are giving me funny looks.
Last night I put new plugs in her and most of the "buzz" went away. Took her for a ride just an hour ago and almost all of it is gone. The old plugs looked GREAT but obviously one or more of them were not firing at all rpms. What is left of the vibration I feel I can atribute to it being time to resync the carbs again. Don't know why they will not stay in sync but it is at least an annual job to resync them as I have found that the slightest bit out and I get high pitch vibrations, I will notice them before I notice anything else wrong.
I wanted to try the Iridium plugs as noted elswhere on this site but out here in the picker weeds if you walk into a parts store and bring up a four syllable word, all you get is a blank look. Don't know why the other plugs would have given me trouble, they didn't have quite 20K miles on them yet! Guess they just don't make anything like they used to!
Be sure and keep us posted, as always, we are interested in anything that effects these machines.

[79XS11F]

HMMM I will change out the plugs again for fun. If I am not mistaken the manual says every 2nd tune up they, the plugs, should be replaced and that would be every 10000 KM. I'm not due but Reg plugs are pretty cheap.
Rob

[BrianB]

I noticed you mention going back to the stock exhaust. Did it previously have a 4 to 1 exhaust? I have read that if installing a 4 to 1 exhaust that the carbs need re-jetted. If this was the case and you went back stock, It could very well be the carbs. I may be way off but just throwing it out there since you still have not found the source.

[79XS11F]

Hey Brian ... Carbs were cleaned inside and out,returned to stock jetting, synced and color tuned so I don't think it's a carb issue. When I tune it for winter storage so it's READY in spring i will see how much the carbs have changed.
Rob

[79XS11F]

Resolved :-)

While installing some engine crash bars this morning I discovered what I think will prove to be the source of the buzz my bike has be producing. I mixed up the engine mounts when I reinstalled my engine. I did not check them closely enough and now see from the parts fiche that the upper front mounts HAVE rubber shoulders and all the others do not.
I used my engine mounts based on condition and did not notice this difference. I has used solid shouldered mounts in the upper front position. I don't have any upper front mounts that are in usable condition so the fix was to put a heavy O-ring over each of the upper front mounts before installing them. I have not been out for a test ride yet but if at idle is any indication the BUZZ is now GONE :-)
Rob

[clisk]

I remember working late one night in my shop and using some spray adhesive and all of a sudden I stood up and the room was spinning! Is that working with a buzz??!!

Ok , just kidding. I chased a vibration around for a year or so and then removed my stock exhaust system and recently put on a 4 into 1 Kerker header. Guess what? The vibration aka buzz is now gone! It was the dang stock exhaust all along I figure. Hope this helps, good luck. Cameron

[79XS11F]

Yes I am sure that the shock RUBBER mounted exhaust is also playing a roll. i did get out for a run this afternoon and the buzz is reduced substantially. S**T ... I can even see things behind me in my mirrors now :-)
Rob

[79XS11F]

Originally posted by clisk
I remember working late one night in my shop and using some spray adhesive and all of a sudden I stood up and the room was spinning! Is that working with a buzz??!!

Ok , just kidding. I chased a vibration around for a year or so and then removed my stock exhaust system and recently put on a 4 into 1 Kerker header. Guess what? The vibration aka buzz is now gone! It was the dang stock exhaust all along I figure. Hope this helps, good luck. Cameron

How do you like the KerKer? Should have given a notable boost in power and should sound NICE.
Rob

[81xsproject]

I hope your mounts prove to be the cause. My suggestion would be to forget the color tune and try again. My recent experience with my new wideband O2 sensor proved what I suspected all along. The colortune sets the carbs up WAY too rich. Turn each of the screws in to seat and keep track of how many turns for each. Get a good average and set all four half to a full turn in from the average. Re-synch the carbs and try it out. Even if it's not the source of your buzz, you'll probably find some low end power you didn't notice you had lost from the colortune.