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Zero Zero TB Synch Gone Bad


oreana123

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I just replaced my front brake pad sets and I thought I'd do something nice for the bike so I accomplished the zero-zero procedure. I now have an occasional backfire and the bike sometimes dies when I rapidly open the throttle from idle, the idle hunts from 1100 to 1600 RPM. Guess I'll do it over again and see if I can get a smoother engine. dopeslap.gif John S

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Zero-zero is only part of a total tune up, and usually only a method of last resort when a normal TB sync won't cure an issue.

 

If that is all you did, you have more work ahead of you. An accurate valve adjustment and plugs should be first. Then at this point re-verification of the TPS voltage would be in order. Followed by a complete TB sync.

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The bike is an R1100R. Although I did not reset the valves, they were at least OK prior to me changing the setting on the TPS. I plan to check out the values of resistance on the TPS- I wonder now if it was somehow damaged. John S

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The bike is an R1100R. Although I did not reset the valves, they were at least OK prior to me changing the setting on the TPS. I plan to check out the values of resistance on the TPS- I wonder now if it was somehow damaged. John S

 

Pay attention!! smile.gif You need to set the voltage on the TPS to .385 between pins 1&4 using a good digital voltmeter. Do this AFTER you have verified the valves are set correctly.

 

Mick

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Oh Oh

I was setting the voltage between the hot pin and a ground on the frame- I'll use the other grounded pin instead. I have a Fluke digital VOM I am using. John S Boise

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From my dusty files:

smirk.gif

Zero – Zero

 

Start by making sure that both TBs are clean and free of deposits.

All adjustments are to be performed only on the left TB during the Zero-Zero procedure.

Connect a Digital Volt Meter (DVM) to the red/white (rearward most) wire that comes out of the TPS using a needle and jumper wire or a piercing test lead.

The red DVM lead to the TPS. Black lead to the bike frame.

Do Not Start The Engine.

With the bike in neutral, the kill switch on and the sidestand up, turn the ignition key on.

Do Not Start The Engine.

Record the “as found” TPS voltage.

TPS voltage “as found”______________________

Now back the throttle plate stop screw out so that is not touching the plate stop.

Make certain the throttle cables are backed off enough to allow the throttle plate to close completely by feeling for slack in the cables and watching for a voltage change.

“Thump” the cable bell crank to make certain the throttle plate is seated in the closed position.

Look for consistent readings.

Record the “as found TPS voltage”______________________

Loosen the TPS screws and rotate the TPS within it’s slots until the voltage stops dropping (typically .006 volts).

Now rotate the TPS back until the voltage reads .004 volts higher than the your lowest voltage (.006 + .004 = .010 volts).

Tighten the TPS screws and recheck your readings, repeat if necessary. Be patient.

Now using the throttle plate stop screw, start turning the screw in until the TPS voltage reaches .370 - .400 volts.

Secure the screw with the locknut.

“Thump” the bell crank and look for repeatability in your voltage readings.

Record the “as left” TPS readings________________________________

Clear the Motronic (pull fuse #5).

Perform a normal TB Sync.

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Thanks Jake

That is the procedure I used and that is why I am concerned that something else is not right. The variable here is the new throttle position screw settings. As a matter of fact, I have gone through the procedure several times adjusting the final voltage value from .370 vdc-.400 vdc trying to get back to where I was before I started. I really am concerned about the way the engine hunts at idle from 1100-1600 rpm. If I rev the bike, it settles back down to an idle at 1100 rpm then after about 30 seconds starts to climb up in rpm to 1600. And by the way, what was the reason for recording the values in the above process- either the values are right or you make them so, no? confused.gif John S

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Thanks Jake

That is the procedure I used and that is why I am concerned that something else is not right. The variable here is the new throttle position screw settings. As a matter of fact, I have gone through the procedure several times adjusting the final voltage value from .370 vdc-.400 vdc trying to get back to where I was before I started. I really am concerned about the way the engine hunts at idle from 1100-1600 rpm. If I rev the bike, it settles back down to an idle at 1100 rpm then after about 30 seconds starts to climb up in rpm to 1600. And by the way, what was the reason for recording the values in the above process- either the values are right or you make them so, no? confused.gif John S

 

Hunting is often due to an air leak downstream of the throttle. Check the O-rings between the throttle bodies and the intakes. For a quick test, spray the area with WD 40 to see if there is a change in running. These O rings will harden with age and can leak even without being disturbed.

 

Andy

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How close are the BBS's set? Think they should be no more than 1/4 -1/2 turn of each other. Don't recall what year bike yours is but you might restet the motronic. But first, make sure your valve adj is correct. Why did you do the tps adj to begin with? Was surging that bad before, or is it worse now?

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I lifted the procedure from our good friend and Father of the Tech-Daze, Tom Roe. The as-found approach essentially give you a way back home if one does something to gum up the whole works. While I have an 1150 (no Zero=Zero), I use the as-found for everything else as it eliminates variables that I might introduce.

 

I know Lentini wrote some stuff that might help - I'll try to find it for you. Is everything clean - intake tube, throttle plate and vacuum port? Did you do a throttle body synch after clearing the Motronic?

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Oh Oh

I was setting the voltage between the hot pin and a ground on the frame- I'll use the other grounded pin instead. I have a Fluke digital VOM I am using. John S Boise

 

John,

You should have let me know you were having problem BEFORE I left Boise. smile.gif I was just up there for the RA Rally.

 

Mick

Tucson

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Mick

 

How can you ride in such hot weather? Still over a hundred here John S wave.gif

 

Shhhhhhhhh,

No one knows it's cooler in Tucson than Boise. smile.gif Only got to 92 here today. High will be 82 by Sunday.

We have such low humidity (normally) that I can stay cool in 100 degree heat with just an evaporative vest on under my Joe Rocket. Sure beats fighting your humidity lately. I think it was 101 up there on the 6th of July.

 

Mick

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BBS = Big Brass Screws, on the back of the throttle bodies. Cleaned BBS's should generally be adjusted for idle to be "about" within 1/2 turn of each other.

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What does it mean if the BBS or more than a 1/2 turn of each other? confused.gif

 

Chris,

It means one side has a bit of a vacuum leak somewhere. The shaft on the right side throttle body seem to wear first. You can test this by attaching your sync tool of choice and press on the pulley at the end of the shaft. See if you can alter the balance (vacuum) by moving that shaft laterally.

 

Mick

Tucson

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