BBS

[tomk99r11]

What would be considered excess difference in BBS adjustment? My bike is within 1/2 turn, but a friend says he has about 1 1/2 turns difference, left vs right. That indicates a 0 = 0 problem doesn't it?

[ShovelStrokeEd]

Not necessarily a zero=zero problem but something is not quite right. Maybe a tight valve setting, maybe a spark plug with an issue or a plug wire. Maybe he just tweaked them once without going through the entire process. Keep in mind that the throttle body sync is the last step, excepting putting the tupperware back on, in a tune up process that must include perfection of, valves, ignition and fuel delivery. Could be that he doesn't have the same compression pressure from one side to the other.

[JonathanE]

Other potential issues:

 

LBS dirty: remove them and clean 'em before starting over.

 

Throttle stops misadjusted by the factory: Unlikely, but technically possible. Although I've never had to do this, after tuning at least a dozen oilheads, my second to last resort would be to set both LBS to 1.25 turns and then adjust the throttle stops to balance vacuum at idle.

 

My last resort would be to take my ride to a dealer.

[russell_bynum]

Throttle stops misadjusted by the factory: Unlikely, but technically possible. Although I've never had to do this, after tuning at least a dozen oilheads, my second to last resort would be to set both LBS to 1.25 turns and then adjust the throttle stops to balance vacuum at idle.

 

To clarify: Adjust the RIGHT throttle stop ONLY.

 

If you muck with the left one, you'll muck with the TPS. Never touch the left throttle stop screw unless you're doing a 0=0.

[tomk99r11]

Agreed. Bike is a 97 R1100. Idle is high, ~1400 rpm, and the screws BBS differ by 1 1/2 turns. Takes a lot of turns toward bottoming out to affect idle and it is still high. Also, the cable at the rt adjuster seems excessive on the right side. Don't get abnormal rpm increase when fast idle lever is on, but this seems abnormal to me, seems should be fairly close to left side cable adjustment. Will check valve adjustment, do a TB sync, and see what happens. Idle stop screws may be messed up, will see what adj of the rt side does after the valve adj and TBS. If nothing changes or change is not enough, I am thinking the 0 = 0 has to be off. I do not know the history of the bike so going from experience with my 99, which runs great since tweeking the 0=0 adjustment made about 5K ago.

 

Thanks for replies

[russell_bynum]

Don't forget to back both barrel adjusters WAY off before you start messing with the idle stop screw. You want to be sure you've got slack in the cables so they're not holding a butterfly off the idle stop screw.

 

Adjust the valves

Slack the cables

clean the throttle bodies and brass screws

set the brass screws the same (I forget how far out they're supposed to be)

balance idle using the right idle stop screw

Make small adjustment to idle speed with the LBS if necessary (verify idle sync when done)

Remove the slack from the left cable using the barrel adjuster (verify idle sync again to make sure you didn't pull tension on the left cable)

Do the off-idle sync by adjusting the right cable at the barrel adjuster

Verify idle sync again, just to make sure

 

If you do all that, and it doesn't run right, or if it idles really high/low, then you most likely need to do a 0=0.

[JonathanE]

Don't forget to back both barrel adjusters WAY off before you start messing with the idle stop screw. You want to be sure you've got slack in the cables so they're not holding a butterfly off the idle stop screw.

 

Adjust the valves

Slack the cables

clean the throttle bodies and brass screws

set the brass screws the same (I forget how far out they're supposed to be)

balance idle using the right idle stop screw

Make small adjustment to idle speed with the LBS if necessary (verify idle sync when done)

Remove the slack from the left cable using the barrel adjuster (verify idle sync again to make sure you didn't pull tension on the left cable)

Do the off-idle sync by adjusting the right cable at the barrel adjuster

Verify idle sync again, just to make sure

 

If you do all that, and it doesn't run right, or if it idles really high/low, then you most likely need to do a 0=0.

 

Russell's got it right.

 

I'd give up if the idle didn't balance within 1/4 LBS turn with the cables SLACK. I'd then move into the throttle stop screws, and only check the TPS for confirmation. If the TPS voltage is off, then adjust it. It's preferred to leave it alone unless it actually needs adjustment.

[tomk99r11]

Right, that'a the procedure. LBS start point is 1 1/5 turns. I think he tried to adjust idle with the stop screw(s)rather than LBS. Doesn't have much experience with his bike. Before going outside the normal stuff, want to make sure the normal stuff is right on. Anyway, will go thru the whole shebang and see what turns up.

[tomk99r11]

Today we went through a valve adj (Rt side intake tight, Lt side ehaust tight), both sides same now. Bike is 97 R1100. Did TBS (did not touch 0=0) using twinmax procedure in a recent BMW mag, which is what I have done since getting the TMx. Got tweeked at first step, and at about 4000 rpm. Seems to me to be pretty big difference in cable adjuster gaps from lock nut, lt side much less space vs rt side, but needle swing at high and low rpm is very steady. And, to get idle down to ~1100 rpm, had to adjust LBS way in on both sides. Think will have him ride for a while and see what gas mileage looks like, but with LBS in so far has to be rich. Had to adjust the rt side idle stop screw, very slightly to get the idle adj right. Does LBS in so far indicate need for a TPS adjustment? Saw somewhere that if idle is too high, tweeking TPS down from .390 to .380 to .370 etc is an option. Anyone had to do that to get LBS/idle set better?

Also, on startup, I hear a click, like a tb slamming? Or am I imagining this?? This makes me ask before touching TPS 0=0 adjustment. TIA for suggestions.

[russell_bynum]

Also, on startup, I hear a click, like a tb slamming? Or am I imagining this?? This makes me ask before touching TPS 0=0 adjustment. TIA for suggestions.

 

My guess would be you've got too much tension in one of the cables, holding the butterfly just off the stop. The clicking is the butterfly smacking the stop.

 

I'm concerned by what you said...that he adjusted the throttle stop screws. If he touched the left side, you're going to have to probe the TPS and reset it to an appropriate voltage before you do any of that other stuff.

 

Saw somewhere that if idle is too high, tweeking TPS down from .390 to .380 to .370 etc is an option. Anyone had to do that to get LBS/idle set better?

 

I believe the computer is expecting between .385 and .400 at idle. If you back the left stop screw out to get down closer to the .385 mark, you will decrease the idle speed. But...I found that the on-off throttle transision gets much more severe the farther away from .400 you are at idle. I spent about 6 agonizing hours screwing around with mine once trying to get everything dialed in. I did a 0=0, then brought the left stop screw up as close to .400 as I could (remember to snap the butterfly a few times...the TPS doesn't always settle in exactly the same place). Then I'd do the idle sync with the right throttle stop. If the idle was too high, I'd got back to the 0=0 and adjust the TPS so a slightly higher voltage with the butterfly closed. Then I'd bring the left idle stop back up as close to .400 as I could, do the idle sync with the right stop screw, check the idle, and repeat until I got everything where I wanted it.

 

The results were noticable, but probably not worth the effort expended (except that I got really good at the 0=0 procedure.

 

Anyway...yeah, you can back the left idle stop screw out a bit to lower the idle...just be sure you keep the TPS voltage above .385 and you should be fine.

[tomk99r11]

Thanks for advice, but the cable tension is good at both adjusters. I reset the motronic, did not touch the tps, and the bike idled low this morning. So, we adjusted the LBS a little, and it seems fine now, at about 1100rpm, no slamming or clacking of anything. The LBS are now out about 1 turn, and I am guessing they are within no more than 1/2 turn of each other. Before messing with anything else, I want him to ride for a while. He says he did not adjust the idle stop screws so.... Bike sounds fine so will see. I really would rather not mess with tweeking the tps unless all else fails. Couple of other things I checked are air filter (no evidence of oil in the box or filter) and spray of wd 40 around tb's for leaks, no rpm increase occurred.

 

May need more advice later but for now I think we got 'er dun!