The Really, Definitely Completely Un-Authorized TBS

[Blind Squirrel]

I took the bike out for a short spin this morning to test the results of my UA TBS attempt. I can sum it up in one word: WOW!!! :yahoo:

It is SO much smoother now. Before I had jerkiness in 1st and 2nd gear. It is gone. I had a slight vibration at 70 MPH (~ 4K). It is mostly gone. I got everything "close" before. I am going to do the UA TBS again and dial it all the way in.

Thanks to everyone that contributed to this thread!

I am now the proud owner of a Carbtune Pro. If there is anyone in the Hampton Roads/Tidewater area (or that is willing to ride to Chesapeake) that wants to use the Carbtune is welcome. Shoot me a PM and I will give you my contact info. We can do it here at my place, or you can borrow the Carbtune for a day to do it at your place.

 

[jsd]

I am new to the forum, and the bike. The vibrations have been getting steadily worse with milage, This sync not only removed the extra vibrations but smoothed out throttle response from idle. By the way my air screws were only out 1/4 turn from factory. 2200 miles. Thanks for the info !

 

[serhan]

Thanks for the post.

I tried normal TBS and it seems to smoothen it out, until 3300 rpm. Then I did the UTBS, and buzzing is now beyond 4K.

One question I have is, do you use loctite on the bypass screws after you set them to their optimal positions?

Thanks,

S.

 

[03HiYoSilver]

Serhan,

Instead of using LocTite, I use just a small dot of Colored Nail Polish at the edge of 1/4 of the Screw.

 

[Fred W]

I've never used anything (loctite or nail polish) I doubt that they actually move at all between TBS'es.

 

[HawkWing]

Did the RDCUA TBS this weekend, in conjunction with Barbarian Jumper mod, on my '08. The synch wasn't off by much- the worst TB was around 15 mm off; the others all needed smaller adjustments. After setting at idle, one TB needed slight adjustment at higher RPM. Used throttlemeister to hold idle at 1000 while adjusting. Wow! The difference is absolutely worth the effort! I thought the bike ran smoothly before these adjustments, but now I know what SMOOTH is! These 2 mods greatly improved smoothness from idle to at least 6000 rpm (haven't had it higher yet). Improved throttle response- feels like there's more torque at low rpm. Taking off from idle much better. Not sure about gas mileage yet; was getting 44.0 before these mods, and after one-half tankful I'm showing 44.5 mpg avg. And I have been "gettin' on it" a bit; just enjoying the improved ride. One minor recommendation I'd make to those doing this procedure: before you adjust anything, observe synch at idle as well as accelerating through higher rpms. In my case, a small change made a big difference. Thanks to all who made this happen. :clapping:

 

[canadianfjrowner]

First of all, sorry to bring up an old thread, but I couldn't find an answer to my question in later threads.

There was talk about calibrating the throttle plates at 4ooo rpm and the engine running away at that rpm. Somebody said it would be great to do this on a dyno as it would create real world torque on the motor.

Now I thought, If you put the bike on the centre stand, put in 5th. gear and rev. the bike to, let's say 60 mph, and load it up by applying the rear brake, it would be just like being on a dyno. At this time, as you apply more brake pressure, you give more gas. This would be the most accurate way to set the butterflies. Of course, you have to dis-engage the ABS system by unplugging on of the speed sensors. This wouldn't hurt the brakes, as long as you don't do this all day long. In normal operation, hauling the bike down from 70 to 0 in a panic stop will put more strain on the brakes than this method for sure.

I'm going to try this, but I need to buy a vacuum set for 4 carbs since I don't know anyone that has one.

Any feedback on my theory would be appreciated.

 

[mcatrophy]

... Of course, you have to dis-engage the ABS system by unplugging on of the speed sensors. ...

No you don't. The ABS light will shout at you, but it won't stop the bike running.

Just watch out for overheating that rear brake.

 

[Blind Squirrel]

First of all, sorry to bring up an old thread, but I couldn't find an answer to my question in later threads.

There was talk about calibrating the throttle plates at 4ooo rpm and the engine running away at that rpm. Somebody said it would be great to do this on a dyno as it would create real world torque on the motor.

Now I thought, If you put the bike on the centre stand, put in 5th. gear and rev. the bike to, let's say 60 mph, and load it up by applying the rear brake, it would be just like being on a dyno. At this time, as you apply more brake pressure, you give more gas. This would be the most accurate way to set the butterflies. Of course, you have to dis-engage the ABS system by unplugging on of the speed sensors. This wouldn't hurt the brakes, as long as you don't do this all day long. In normal operation, hauling the bike down from 70 to 0 in a panic stop will put more strain on the brakes than this method for sure.

I'm going to try this, but I need to buy a vacuum set for 4 carbs since I don't know anyone that has one.

Any feedback on my theory would be appreciated.

I can see it now... You lean on the back of the bike enough to make the rear tire touch the pavement and ZOOOOOOM!!! Off it will go without you!

Please make sure to video it so I can laugh my *** off at you!

 

[Fred W]

There is apparently no reason to do all of that. The original procedure (adjusting the plates at idle with the air screws all closed) has worked for every person that has tried it. The 4000 rpm stuff is unnecessary. I wouldn't abuse my bike by trying to rev it to 4000 rpm and hold the rear brake on at the same time. The likelihood that you will be able to do that and also adjust the plates is pretty remote.

But if you do try it, do be sure to capture the event on video.

 

[canadianfjrowner]

There is apparently no reason to do all of that. The original procedure (adjusting the plates at idle with the air screws all closed) has worked for every person that has tried it. The 4000 rpm stuff is unnecessary. I wouldn't abuse my bike by trying to rev it to 4000 rpm and hold the rear brake on at the same time. The likelihood that you will be able to do that and also adjust the plates is pretty remote.

But if you do try it, do be sure to capture the event on video.

I would take the measurement, then shut it down, then adjust and re-try. As long as no-one has done it, I don't mind being first. As for safety, than is easy to overcome with some common sense. Just proper secure the front tire down so it won't lift and be prepared for centrifical forces. I'll let you know the results. If it goes bad, trust me there will be no pictures.

 

[Blind Squirrel]

If it goes bad, trust me there will be no pictures.

<_< You're no fun.

 

[SCB]

I think I'm with Canadian on this. As I read the thread and guys suggested using a dyno my first thought was to put it in gear and use the rear brake. I guess I would do the procedure the way Fred et al lay it out and then, with the manometer still hooked up, put it in gear, load up the engine and see what happens. I don't think you'd have to hold it there for more than a few seconds to see if it holds the balance. Not sure what I would do with that new found info but I think it would be interesting.

 

[stevet]

Now I thought, If you put the bike on the centre stand, put in 5th. gear and rev. the bike to, let's say 60 mph, and load it up by applying the rear brake, it would be just like being on a dyno. At this time, as you apply more brake pressure, you give more gas. This would be the most accurate way to set the butterflies. Of course, you have to dis-engage the ABS system by unplugging on of the speed sensors. This wouldn't hurt the brakes, as long as you don't do this all day long. In normal operation, hauling the bike down from 70 to 0 in a panic stop will put more strain on the brakes than this method for sure.

I'm going to try this, but I need to buy a vacuum set for 4 carbs since I don't know anyone that has one.

Any feedback on my theory would be appreciated.

I witnessed this procedure. 4th gear was used, modest brake pedal used to apply drag/load on the rear wheel. I don't recall speed/RPM used, but I'm thinking somewhere up in the mid-high 3000 range. Reports after the fact from the bike owner were of noticeable reduction of vibration and possibly other seat-of-the-pant performance improvements. Just be careful- doing this isn't any different from riding your brakes down long hills, you can overheat the system just as easily.

 

[Fred W]

I witnessed this procedure. 4th gear was used, modest brake pedal used to apply drag/load on the rear wheel. I don't recall speed/RPM used, but I'm thinking somewhere up in the mid-high 3000 range. Reports after the fact from the bike owner were of noticeable reduction of vibration and possibly other seat-of-the-pant performance improvements. Just be careful- doing this isn't any different from riding your brakes down long hills, you can overheat the system just as easily.

Questions for those who've tried this:

Did you try adjusting the throttle plates using my "close all 4 air screws at idle" technique first?

And if so, how much difference (need for further adjustment) was there when you tried the dynamic loaded method using the rear brake?

 

[canadianfjrowner]

I witnessed this procedure. 4th gear was used, modest brake pedal used to apply drag/load on the rear wheel. I don't recall speed/RPM used, but I'm thinking somewhere up in the mid-high 3000 range. Reports after the fact from the bike owner were of noticeable reduction of vibration and possibly other seat-of-the-pant performance improvements. Just be careful- doing this isn't any different from riding your brakes down long hills, you can overheat the system just as easily.

Questions for those who've tried this:

Did you try adjusting the throttle plates using my "close all 4 air screws at idle" technique first?

And if so, how much difference (need for further adjustment) was there when you tried the dynamic loaded method using the rear brake?

Thanks Fred W

That's exactly what I wanted to try. If after doing this sequence, there is no difference between idle and load, then in the future, the load calibration won't be needed. I'm still waiting for the tool to set it up. I plan to do it at the same time as installing the cruise control, as I will be there anyway.

 

[Bungie]

Tonight is tune up night (if I can keep the polar bears from bothering me that is). New plugs and air filter going in which means it's time for a TBS.

The plan is to do a regular TBS then check it with the air screws closed as per this technique. If it's out, I'll give it a go, if not, I'll just restore them.

My bike has always felt rough over 4500 rpm. But its got a REAL sweet spot between 3000-3500. Which is just a hair to low for the speed I like to cruise at. I would absolutely love to be able to either make the bike always feel like that sweet spot, or, just shift it up the RPM range a bit.

I'll keep ya informed.

 

[Fred W]

Tonight is tune up night (if I can keep the polar bears from bothering me that is). New plugs and air filter going in which means it's time for a TBS.

The plan is to do a regular TBS then check it with the air screws closed as per this technique. If it's out, I'll give it a go, if not, I'll just restore them.

My bike has always felt rough over 4500 rpm. But its got a REAL sweet spot between 3000-3500. Which is just a hair to low for the speed I like to cruise at. I would absolutely love to be able to either make the bike always feel like that sweet spot, or, just shift it up the RPM range a bit.

I'll keep ya informed.

Very cool, Bungie! That's a data point that has been (to this point) uncollected.

My gut instinct is that you'll find it unbalanced, but I am anxious to her your real observations. Especially if you go through the next step of adjustment and it makes a difference.

 

[Bungie]

My gut instinct is that you'll find it unbalanced, but I am anxious to her your real observations. Especially if you go through the next step of adjustment and it makes a difference.

Darkness fell before I could try the technique.

Just for reference, my cylinders 2-4 were all relatively close and entirely acceptable, my number 1 cylinder was down quite a bit (this on a Morgan CarbTune). No amount of dicking with the hose on the fitting made any difference at all.

The only way I could get it to rise to even close to the other levels was to completely close the air screw. Obviously, something is haywire. Could be a couple of things I want to check first. I backed it back out 3/4's of a turn to put it back where it was and then buttoned it up for the night (and went for a short ride). Bike feels the same. Go figger

Now it could be that the number 1 cylinder throttle plate is out of sync. But I want to eliminate the possibility of any vacuum leaks on that cylinder between the throttle body and the head first, simply because I don't want to be correcting the a vacuum leak with the throttle plate adjustment. I'll get that done tomorrow night and report back.

 

[Fred W]

Steve,

There is also a possibility that the #1 air screw is the only normal one and the other 3 are all plugged up (or closed down). Make sure that adjusting each screw open and closed has the expected effect (opening drops vacuum in that cylinder).

Also, it's really easy to get them back to wherever they are now just by counting turns to fully closed and writing them down.