TBS Erratic and Front Brake Noise

[gazza]

Hi folks

First of all regarding TBS. When I have the Carbtune connected, at idle #2 cylinder column is more erratic than the 1,3 and 4. Any reason why this would be??.Could it be valve adjustment related considering this has not been done in the last 40,000kms. I have done the plugs recently.Secondly, I have a shhhhh coming from the front brakes when even applying the slightest pressure on the brake lever. Originally I thought this may have been the forks but have concluded that it is not. Is this the norm with the brakes??

Regards

Gaz

 

[Pterodactyl]

Normally best to make sure the valves are set correctly before tackling the TB sync. If the the valves are off, then you will be chasing your own tail trying to get the TBs set. Shhhh from the brakes is new to me.

 

[Pepperell]

Is the idle speed at 1100 rpm? If it's lower it will run a little ragged.

Shhh may actually be from the tires. Does it Shhh if you spin the wheel by hand with the front jacked up?

 

[RaYzerman19]

Shhhh could be brake pads on rotors maybe clearing contamination off, or if happening every time, might be the early signs of pad worn too thin.... best check thickness and condition..

 

[Bounce]

I had to nail the brakes hard when in the vicinity of Lake City, Fla. Some ****** had stopped dead in the middle of a back road for no apparent reason. When I crested the rise (Fla doesn't have hills except at overpasses), there it was. I was loaded for a multi-day rally so was running heavy when I had to hammer the brakes harder than maybe ever before or since[1]. I remember thinking at the time (even through ear plugs) that the brakes sounded like cicadas in the summer. So, sort of like a "shhhh" but more.

[1] Not the first time I was glad I had rotated the non-ABS, gen 1, foot brake pedal one tooth downward on the shift shaft spline.

 

[ionbeam]

...When I have the Carbtune connected, at idle #2 cylinder column is more erratic than the 1,3 and 4. Any reason why this would be...Secondly, I have a shhhhh coming from the front brakes when even applying the slightest pressure on the brake lever...

Swap the #2 hose with the #1 hose on the throttle body. If the erratic reading follows the hoses, it's the way the damper is installed in the #2 Carbtune hose, or the length of the hose. I'm betting it's the tool and not the #2 cylinder.

Shhhhhh is not a problem. My brakes will make that sound while riding in the rain and for a while after. I suspect it would make that noise if my bike had been washed but I'll probably never know about that

As mentioned, inspect your pads for wear and with the front wheel in the air try to spin the front tire to check for abnormal brake drag. It is common for the front wheel to spin less than one turn even with a healthy push. I get that noise more with OEM brake pads than aftermarket.

 

[gumba]

I agree with what has been said. Damper for bouncing TBS and I would add: I have had medicor brake performance over the years. That is until the last time I replaced pads. This last time I took the time to thoroughly clean the calipers. I spent half a day with a good cleaner and compressed air. It's a dirty ******* job, but the return is unbelievable. My front end now rattles over a slow bumpy surface. I worry when I don't have that.

 

[FJRBluesman]

Gunny on valves first then TBS. How many miles on the bike and how many miles since the last valve check (if any)? How is your idle, does it fluctuate? Could have a leaky Carbtune tube to that cylinder or poor connection/seal. Check all that first, swap the tubes to cylinders to see if the problem moves.

Shhhhh in front brakes is fairly normal. My bike still does it and it's loudest with new brake pads. Those little holes in the rotors can play music.

Wait a minute... you said brain trust. Forget what I said.

 

[gazza]

Guys

Thanks for all the feedback. I will get on to all of the above ASAP.Think i will firstly hook up the carbtune again and swap the hoses around. If the same i'm in for a valve check.No valve check done for the last 25,000 miles.The bike has done (80,000miles) and yes the idle does fluctuate.I reckon its number 2 cylinder but i'm gonna recheck it anyways. Get it warm(2 bars) set it on 1100rpm, go for a quick blat and let it idle again and it dropped to 980-1000 rpm. On to the brakes and i recall that most of the time when i move it the pads are rubbing against the disks and occasionally after a ride the next morning they are sort of stuck on the disks momentarily. Probably heat related but is that normal??.

Gazz

 

[mcatrophy]

Guys
... On to the brakes and i recall that most of the time when i move it the pads are rubbing against the disks and occasionally after a ride the next morning they are sort of stuck on the disks momentarily. Probably heat related but is that normal??.

Gazz

Any non-braking rub shouldn't heat the discs up. Go for a few miles, coast to a stop (or only use the back brake), feel the discs. If significantly warm, you have a problem.

Sticking first thing is normal IF they were damp when put to bed, a little rusting under the pad will have occured. If this is the case, if you roll the bike forward a little, you'll see a ghost image of the pads on the disc. Nothing to worry about.

 

[Bounce]

Get it warm(2 bars) set it on 1100rpm, go for a quick blat and let it idle again and it dropped to 980-1000 rpm.
Gazz

so reach down at any stop and turn it back up to 1100. easy peezy and where it should be.

 

[bluesdog]

Also worth checking the carbtune readings at @ 4000 RPM for a few moments.

 

[Fred W]

Bouncing vacuum readings are not a problem. It is not indicative of a valve being out of adjustment. If it were time to check/adjust the valves I would certainly do that first before a TBS, but I wouldn't do a valve check early just because the vacuum is bouncing on your Carbtune.

Unlike other synchronizer tools with liquid (mercury or ATF) there is no viscous damping of the vacuum readings on the Carbtune. It is just a metal rod in a glass tube hooked up to the vacuum source, so if the vacuum source is pulsating the reading will also pulsate. The manufacturer attempts to mitigate the pulsation (to make it easier for the user to easily read a vacuum level) by having you cut the bigger diameter black tubing and stuff a short length of clear vinyl tubing inside to act as an "orifice". It is important that the smaller orifice "snubber" is closer to the engine end of the tubing, so you might want to check that yours are installed that way when you use them. Having the larger volume of air on the instrument end is what averages out some of the pulsations coming through the snubber.

A good way to see how much that vacuum from the intakes is actually pulsating is to hook your Carbtune up directly (with no little snubbers installed). You'll see that all 4 vacuum reading fluctuate wildly and all of tha action makes it hard to visually estimate the average excursions.

Generally when I'm doing a TBS I'll see one or more of the readings fluctuating. As long as it is small enough so that you can make a visual average of the reading, do that and all will be well.

 

[gazza]

Thanks Fred.

Gaz

 

[RaYzerman19]

I agree with what has been said. Damper for bouncing TBS and I would add: I have had medicor brake performance over the years. That is until the last time I replaced pads. This last time I took the time to thoroughly clean the calipers. I spent half a day with a good cleaner and compressed air. It's a dirty ******* job, but the return is unbelievable. My front end now rattles over a slow bumpy surface. I worry when I don't have that.

You may have cleaned out the accumulation of dirt from around the rotor rivets..... they're floating rotors. That rattle drove me bananas when I first got the Feej, til I found out what it was (from postings here). Grab your rotors and turn them back and forth to hear the click (if cleaning them was the thing that started it again).

 

[mcatrophy]

Just thought I'd add a bit about rust on the brake disc.

Took my bike out of the garage today to wash it (ok, I'm possibly ghey), having put it away wet a couple of days ago. The brakes were sticking when I came to roll it, they freed with a cracking sound, and then made a "shhhhhing" sound as I moved it, louder as I squeezed the front brake lever to slow the bike down.

Took a couple of pictures to illustrate what I said in my post above about rust.

General view of the wheel (click on image for larger view):


Brake disc with rust and brake pad image, and enhanced to help see:


All that rust, although clearly visible, is barely discernible when running a fingernail over it.

 

[gazza]

Hi guys

Well, One problem sorted. I removed the front brake pads today as i had a new pair from Yamaha sitting on the workbench for the last six months. Anyway, I removes the existing ones which were not really worn and put the brand new pair in. On comparing the two i see the new pair has a vertical groove running through the middle of each pad and the old ones did not. Not sure if the old ones were Yamaha or not but anyway the Shhhhhhh when applying the front brakes has all but gone. Yippy.

Regards

Gazz

 

[mcatrophy]

The groove is a wear indicator, not intended to affect any noise.

If the old ones were OEM and had no groove, they really needed replacement. Had they gone through to the backing metal, they would make an awful noise as they gouged away the disc.

The groove does get filled with brake dust and can be difficult to see unless you probe for it with something sharp.