The Really, Definitely Completely Un-Authorized TBS

[canadianfjrowner]

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.

There are a number of things you need to check. If you are concerned about a vacuum leak between the throttle body and the head, you will need to use a smoke machine. You may need to ask a reputable repair garage (automotive) and see if they can help you. I own a repair facility and have all tools available. I've worked on many toys (snowmobilees etc.) and continue to be surprised by how poorly these machines are put together. Nothing sounds better than a high revving engine all ballanced out.

Good luck

 

[Bungie]

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).

After I picked up the Morgan I did my first TBS with it. 2 of the 4 screws were closed, 1 was backed out about 2.5 turns. This is from a 5 Star Yammie dealer. I baselined them all at one turn out and reset the sync. None required more than half a turn either way to balance them to number 3. The bike smoothed out considerably after that one.

Given that the last sync was entirely normal, I'm going to switch to a different tube on the Morgan. Just to eliminate the gauge being the cause. If that checks out fine, I'll do a Quick-Start test on that manifold boot (Spritz some Quick Start around the joints to see if the vacuum jumps). The bike had a valve check last year and maybe something got a little cocked up.

I'll keep you guys in the loop.

 

[BlackStar]

Just curious here. It looks like the FJR has balance tubes running between the TB's like my FZ1 has. Wouldn't it be better to temporarily plug these to eliminate any flow between the TB's? Realizing that if the vacuum is equal, there shouldn't be any flow. Would it allow one to get the sync even closer? Apparently, they can't flow enough to prevent a bad sync.

 

[canadianfjrowner]

Well, last night I finally had the chance to do the TBS. I was surprised at what I found. First I managed to set up the fuel tank next to the bike so I had lots of room for adjustments. The bike now has about 1300 miles on it. All the idle adjust screws were set the same at 5/8th of a turn. The hot idle was nowhere near perfect. I went ahead and closed them all and reset the idle rpm to 1000rpm. I could see that the base ballance was way off. I went ahead and revved the bike up in neutral to 4000 rpm and found that Cyl.# 1 and 4 had a lot more vacuum than 2 and 3. Now comes the kicker. In one of my last posts on this thread, I was talking about loading up the engine (like I was riding down the road, since nobody cares if the butterflies are ballanced when revving in neutral)and seeing what kind of vacuum I was getting then. I found it easiest to leave the bike in second gear and rev it up to 4000rpm. Then I applied the rear brake and gave more throttle and kept the rpm to 4000. The numbers were way different than when revving in neutral. I reset the throttle bodies the best I could. The rear brake was overheating by the fourth pull, so I need to cool down the rear brakes with a water spray next time I do this. I reset the idle adjust and rpm when all done. I also installed a Audiovox cruise control so once I get the necesary vacuum hose needed to finish the install, I can take it for a ride.

I would love to see someone do this TBS on a dyno. I hope someone else will try the same procedure in order to confirm or negate my findings.

 

[Fred W]

Well, last night I finally had the chance to do the TBS. I was surprised at what I found. First I managed to set up the fuel tank next to the bike so I had lots of room for adjustments. The bike now has about 1300 miles on it. All the idle adjust screws were set the same at 5/8th of a turn. The hot idle was nowhere near perfect. I went ahead and closed them all and reset the idle rpm to 1000rpm. I could see that the base ballance was way off. I went ahead and revved the bike up in neutral to 4000 rpm and found that Cyl.# 1 and 4 had a lot more vacuum than 2 and 3. Now comes the kicker. In one of my last posts on this thread, I was talking about loading up the engine (like I was riding down the road, since nobody cares if the butterflies are ballanced when revving in neutral)and seeing what kind of vacuum I was getting then. I found it easiest to leave the bike in second gear and rev it up to 4000rpm. Then I applied the rear brake and gave more throttle and kept the rpm to 4000. The numbers were way different than when revving in neutral. I reset the throttle bodies the best I could. The rear brake was overheating by the fourth pull, so I need to cool down the rear brakes with a water spray next time I do this. I reset the idle adjust and rpm when all done. I also installed a Audiovox cruise control so once I get the necesary vacuum hose needed to finish the install, I can take it for a ride.

I would love to see someone do this TBS on a dyno. I hope someone else will try the same procedure in order to confirm or negate my findings.

Good report.

And I agree... I do not place much credence in the balance you see when just freely revving the engine to 4k rpm. Any time I have done this after balancing using my adjustment at idle method I always see disparity between cylinders.

Question: After making the throttle plate adjustments at 4k rpm loaded using the rear brake, what did the vacuum balance then look like at idle (with the air screws still all closed)?

You mentioned that they were off initially, what about after making the dynamic loaded adjust?

 

[canadianfjrowner]

Well, last night I finally had the chance to do the TBS. I was surprised at what I found. First I managed to set up the fuel tank next to the bike so I had lots of room for adjustments. The bike now has about 1300 miles on it. All the idle adjust screws were set the same at 5/8th of a turn. The hot idle was nowhere near perfect. I went ahead and closed them all and reset the idle rpm to 1000rpm. I could see that the base ballance was way off. I went ahead and revved the bike up in neutral to 4000 rpm and found that Cyl.# 1 and 4 had a lot more vacuum than 2 and 3. Now comes the kicker. In one of my last posts on this thread, I was talking about loading up the engine (like I was riding down the road, since nobody cares if the butterflies are ballanced when revving in neutral)and seeing what kind of vacuum I was getting then. I found it easiest to leave the bike in second gear and rev it up to 4000rpm. Then I applied the rear brake and gave more throttle and kept the rpm to 4000. The numbers were way different than when revving in neutral. I reset the throttle bodies the best I could. The rear brake was overheating by the fourth pull, so I need to cool down the rear brakes with a water spray next time I do this. I reset the idle adjust and rpm when all done. I also installed a Audiovox cruise control so once I get the necesary vacuum hose needed to finish the install, I can take it for a ride.

I would love to see someone do this TBS on a dyno. I hope someone else will try the same procedure in order to confirm or negate my findings.

Good report.

And I agree... I do not place much credence in the balance you see when just freely revving the engine to 4k rpm. Any time I have done this after balancing using my adjustment at idle method I always see disparity between cylinders.

Question: After making the throttle plate adjustments at 4k rpm loaded using the rear brake, what did the vacuum balance then look like at idle (with the air screws still all closed)?

You mentioned that they were off initially, what about after making the dynamic loaded adjust?

They were way off. BTW, it sounds sooo good when you dial in the idle as you get closer to the ballance point, you can just hear that engine starting to purr. Almost the same when you ballance out a Ferrari v12 with the stupid bosch fuel injection.

 

[Fred W]

They were way off. BTW, it sounds sooo good when you dial in the idle as you get closer to the ballance point, you can just hear that engine starting to purr. Almost the same when you ballance out a Ferrari v12 with the stupid bosch fuel injection.

OK, just to clarify... You are saying that after adjusting it loaded at 4k the vacuum was still way off at idle, right?

But then you opened up the 4 air screws the same amount and balanced them at idle and that's when you got the great Ferrari sound, right?

I guess the real proof of the pudding will be in the road test. The times that I have got it it "just right" the difference in vibration is quite remarkable. I'm keeping my fingers crossed that you've found a better method.

BTW - No experience with Ferrari V-12's here, but not for a lack of desire...

 

[canadianfjrowner]

They were way off. BTW, it sounds sooo good when you dial in the idle as you get closer to the ballance point, you can just hear that engine starting to purr. Almost the same when you ballance out a Ferrari v12 with the stupid bosch fuel injection.

OK, just to clarify... You are saying that after adjusting it loaded at 4k the vacuum was still way off at idle, right?

But then you opened up the 4 air screws the same amount and balanced them at idle and that's when you got the great Ferrari sound, right?

I guess the real proof of the pudding will be in the road test. The times that I have got it it "just right" the difference in vibration is quite remarkable. I'm keeping my fingers crossed that you've found a better method.

BTW - No experience with Ferrari V-12's here, but not for a lack of desire...

Yes, the idle with the air bypass screws closed was off. Quick adjustment was all that was needed. Took it for a spin and wow. No vibration at 65 to 75 mph. Also when you labour the engine at low rpm it seems to pull better without as much complaining. I will do my friend's bike next and see the before and after on that one.

 

[Fred W]

I'd be glad to try this too and add yet another data point. It is all easily reversible if it doesn't pan out.

Well, that is except for the wear and tear to the rear brake

Now, we may want to dream up a way to make a poor man's dyno type load.

PS - what rpm does 65-75 equate to on a 2nd gen. I know that would be 3800-4200 rpm on my 1st gen.

 

[ionbeam]

...The rear brake was overheating by the fourth pull, so I need to cool down the rear brakes with a water spray next time I do this...

:ermm: Holy warped rotor! Perhaps a fan would be a better idea.

 

[mcatrophy]

...PS - what rpm does 65-75 equate to on a 2nd gen. I know that would be 3800-4200 rpm on my 1st gen.

All is revealed here (clicky).

Or, just the graph:

(Click on image for larger view)

 

[canadianfjrowner]

I'd be glad to try this too and add yet another data point. It is all easily reversible if it doesn't pan out.

Well, that is except for the wear and tear to the rear brake

Now, we may want to dream up a way to make a poor man's dyno type load.

PS - what rpm does 65-75 equate to on a 2nd gen. I know that would be 3800-4200 rpm on my 1st gen.

I don't think the speed of the rear tire has as much to do with the set-up as the ability to put a descend load on the engine at 4000rpm and the ability to control it at that rpm as you increase load. I found it easy to raise the rpm to 4000 and then increase load and increase throttle at the same time. BTW. The bike on the centre stand was very stable. I was a bit worried about centrifical forces playing a role in the stability but all was good.

On another note the ability of controlling the rear brake temp. before it gets hot with a water spray shouldn't affect the warpage of the rear rotor. just don't cool it when it is already super hot. Some years ago I had an automotive dyno that I could have used but I sold it 5 years ago. There will be tons of dynos for sale in Ontario by January of next year for basically the price if the steel. There are over 2000 dynos that will be de-commisioned for emisions testing.

 

[Yamifz1]

I recently ( a month ago) bought a 2006 FJR and have been very displeased with it ever since because like many others have noted it hurts to ride it. After a few hours my wrist and elbow are aching and I just want to get off the bike. I bought it because I was looking for similar performance as my FZ1 with a little more comfort but turns out my FZ1 is more comfortable to ride. I knew that something had to be done.

So I finally got a little time to do some work on my bike today. I had planned on doing the throttle spring release, sync the TBs and changing the plugs all at once, unfortunately the plugs were ordered but they did not come in yet. So this morning I released the spring one turn ( definitely a big improvement) and did you Un-authorized TBS minus the engine under load portion as I figured just lining up the plates and then syncing everything would be an improvement. Here is how things lined up at idle with nothing done ti the bike so as to get a baseline.

I then followed the procedure as outlined, which by the way was quite simple except for reaching the screws for the plate adjustments. That required a bit of work lining things up and holding the throttle shut at the same time, none the less I got it done. Here is how things looked when I was finished.

I went out for a very short ride afterwards just to ensure that everything was in working order and right away I saw improvements. The throttle was far smoother and it did not jerk forward in the turns as you accelerated. I also had a fairly noticeable vibration that could be felt in my hands and butt from 4000-4500 RPM. Now I can barely even notice it. I am looking forward to going out for a few hours and seeing what a difference these changes have made. My bike may now be rideable and may only require a change in the handlebar position.

Thanks for the write up and pictures, they made this job far easier.

 

[Fred W]

I'd be glad to try this too and add yet another data point. It is all easily reversible if it doesn't pan out.

Well, that is except for the wear and tear to the rear brake

Now, we may want to dream up a way to make a poor man's dyno type load.

PS - what rpm does 65-75 equate to on a 2nd gen. I know that would be 3800-4200 rpm on my 1st gen.

Well, today was oil change day. So I propped the tank up and checked the TBS (it's on my regular 5k maintenance list anyway) and checked the balance 5k miles after my last TBS. As is usual, it was off a little bit.

I then closed down all four air bypass screws and boosted the idle up to 1100 rpm. There was some vacuum misbalance there too. Mostly it was in the most difficult adjustment between #2 and #3. I adjusted that out using my normal procedure (at idle). This still requires stopping and starting the engine to get at that middle linkage adjustment screw, then adjust the two outboard cylinders last with the engine running (much easier).

When I was satisfied all was good I straddled the bike standing up on the pegs (no seat and the tank up) put it into 2nd gear and modulating the rear brake, released the clutch and ran the engine speed up to ~4k rpm. I saw no discernable difference in vacuum there on my bike as compared to at idle. Since I saw nothing that could be improved on by adjustment I didn't do any. Also, FWIW, my vacuums were pretty close as I just revved the engine freely (not under any brake load).

I then opened each air screw 1 turn, readjusted the idle back down to 1100 rpm, and then balanced them at idle again using the air bypass screws. Not much adjustment was required. This last part seems a bit redundant since everything was already balanced at idle before opening up the 4 screws. Some day I may try closing them all down and leaving them there to see what happens.

Now remember, I am dealing with a 1st gen bike. 1st Gen idle adjust is a screw that adjusts the mechanical stop for the throttle shaft bell crank. My understanding is that 2nd gens use something else related to an air bypass, so that may be the big difference in our results.

 

[canadianfjrowner]

I'd be glad to try this too and add yet another data point. It is all easily reversible if it doesn't pan out.

Well, that is except for the wear and tear to the rear brake

Now, we may want to dream up a way to make a poor man's dyno type load.

PS - what rpm does 65-75 equate to on a 2nd gen. I know that would be 3800-4200 rpm on my 1st gen.

Well, today was oil change day. So I propped the tank up and checked the TBS (it's on my regular 5k maintenance list anyway) and checked the balance 5k miles after my last TBS. As is usual, it was off a little bit.

I then closed down all four air bypass screws and boosted the idle up to 1100 rpm. There was some vacuum misbalance there too. Mostly it was in the most difficult adjustment between #2 and #3. I adjusted that out using my normal procedure (at idle). This still requires stopping and starting the engine to get at that middle linkage adjustment screw, then adjust the two outboard cylinders last with the engine running (much easier).

When I was satisfied all was good I straddled the bike standing up on the pegs (no seat and the tank up) put it into 2nd gear and modulating the rear brake, released the clutch and ran the engine speed up to ~4k rpm. I saw no discernable difference in vacuum there on my bike as compared to at idle. Since I saw nothing that could be improved on by adjustment I didn't do any. Also, FWIW, my vacuums were pretty close as I just revved the engine freely (not under any brake load).

I then opened each air screw 1 turn, readjusted the idle back down to 1100 rpm, and then balanced them at idle again using the air bypass screws. Not much adjustment was required. This last part seems a bit redundant since everything was already balanced at idle before opening up the 4 screws. Some day I may try closing them all down and leaving them there to see what happens.

Now remember, I am dealing with a 1st gen bike. 1st Gen idle adjust is a screw that adjusts the mechanical stop for the throttle shaft bell crank. My understanding is that 2nd gens use something else related to an air bypass, so that may be the big difference in our results.

Did you load up the engine by roughly the same amount as if you were riding?

 

[canadianfjrowner]

As I replied to the last post, I realized that nobody actually measured the amount of vacuum present at 65 mph cruising. I just installed a cruise control, to it will be easy to take this measurement. Once we have this vacuum reading, (which is a measurement of engine load that the MAP sensor looks at), we can duplicate this same load while standing still on the centre stand loading up the engine with the rear brake. Will let you all know the results soon.

 

[Fred W]

Did you load up the engine by roughly the same amount as if you were riding?

Yep, I sure did. After two short runs or maybe 10-15 seconds each (I repeated my first attempt to be sure) my rear brakes were good and hot.

As I replied to the last post, I realized that nobody actually measured the amount of vacuum present at 65 mph cruising. I just installed a cruise control, to it will be easy to take this measurement. Once we have this vacuum reading, (which is a measurement of engine load that the MAP sensor looks at), we can duplicate this same load while standing still on the centre stand loading up the engine with the rear brake. Will let you all know the results soon.

The vacuum level at 65 mph cruise will be somewhat lower than it is at idle because the throttle butterflies are open.

The original premise of balancing the vacuums under load was that the engine would be pumping more air, so more flow through the intakes at that rpm. I guess now I am second guessing whether the air flow is that much different when loaded vs unloaded? Yes, the airflow will be greater, but the throttle plates will be somewhat more open when loaded, which means any variation in angle of those plates would be of less significance. What may be of more significance would be variation in the intake tracts, valve lift and duration, etc.

 

[canadianfjrowner]

It would be great to be able to communicate with a technician that sets up race bikes on the track. I imagine they study this kind of thing to death, because the more HP, the more speed.

 

[Chuck35]

Thanks Fred for the guide and pictures! They made life much easier for me this am.

Having been an automotive tech fr over 3 decades, I feel I am qualified to point out an oversight I discovered.

The little rubber plugs go back on BEFORE the gas tank. :lol:

Mine weren't off as far as I had hoped, but they are spot on now!

On my test drive I was preoccupied with my speedo and gps (new speedodrd) but as I neared home with a saddlebag reeking of fried chicken and mashed taters, I realized I hadn't been locking the throttle and shaking my wrist.

 

[VanHarlan]

Well Here Goes . . . at 29,000 miles I'm ready to change the plugs last night and attempt the UN-Authorized TBS . . . Fred's info and theory all make good sense . . . after all - the adjustment screws are there, right?

I installed 4 new NGK Iridiums . . . and started the engine, letting her warm up to normal operating temperature. I did all the preliminary non-sense like shutting down the air screws, etc.

Oddly . . my engine ran fine without adjusting the idle after the air screws were shut down. My 1 & 4 were wildly out of balance from 2 & 3 not to mention 2&3 were a little whack. After trial and error, checking, rechecking, I was happy with the initial results and moved on to "authorized" sync. Also interesting to note is that once I open all the air screws one complete turn CCW my idle went from about 1100 to 1400-1500 (remember I did not have to adjust the idle speed to compensate for the shut down air screws). I adjusted the idle and proceeded with a normal sync.

I took the bike on a 400 mile jaunt today through the mountains & forest of northern PA and I'll say I don't think she's ever run so well.

Then throttle response was reliable and predictable . . . and much smoother than it has been in the recent past.

After today's run I plan on going back in and re-doing it since it's obvious that my throttle blades were way out of alignment.

Thank you to Fred and everyone who has discussed this topic and added their input . . . it's amazingly simple and the results are well worth the effort. Well done gentlemen.