Synchronization knob and throttle bodies

[slowkitty]

Dear Gents,

 

My mate and I are attempting TPS setting and throttle-sync on a V11 that does not run very well now. The bike in question has a mileage of 15K and valves had just been adjusted cold.  The main thing is that the bike cannot hold idle when cold, and exhaust smells rich. Sooty plugs seem to confirm that.

 

The air bleed screws were 3/4 out when I checked.

 

I managed to attain the 150mV and 521 mv settings.

 

 

 

But the bike will not idle well; in fact worse than before I started. Interestingly, when started, the tacho will show a nil reading for about 2 seconds before the needle jumps to 1100 and then it will not sustain without the use of the throttle.

 

It seems to me that the syncronization knob at the rod connecting the throttle bodies had been messed with in the past and may be a source of the troubles. I have several questions:

 

1. Will disconnecting the connecting rod from the ball joint at the right side of the bike in any way upset any prior settings?  Conversely, does reconnecting it in any way affect the throttle bodies?

 

2. Assuming one messes with the knob while the bike is without the engine running, what is the effect?

 

3. Assuming that the bike is running and at idle, what is the effect of turning the knob? 

 

4. Will disengaging the throttle idle screws on both sides in any way affect the function of the synchronization knob, or the 2 system are linked?  

 

Please forgive me if the questions seems noob in nature.  Just started fiddling with the bike and want to know the exact function of the syncronization knob.

 

Thanks

[Desdinova]

Hi I don't post often anymore but I am subscribed so I get alerted when topics come across that I may actually know something about.    

 

Because there is some question of previous tinkering, before you go down the rabbit hole... DISCONNECT the throttle cables and ensure both throttles are closing all the way, with no cables attached.  Get a good light in there and inspect visually. Ensure the throttles is opening and closing TOGETHER.   Check the TPS voltage, then put the cables back on and then check the TPS voltage again and insure it is THE SAME.   I had an issue that had your symptoms , and after nearly a year of putzing it turned out that when I came off the throttle, the throttle was "almost" closed, but not really fully closed.  In my case it was due to a bur on the cable end ....  This through everything else off exponentially.   

 

Once I cured that...  the bike damn near tuned itself..    Set the TPS voltage and badabing.. nice idle.   Hooked up the merc tubes...  and balanced them right up.

 

Hope this helps.  

[czakky]

To answer your questions

 

1. No, it should go back to near your settings after connecting/disconnecting. Just to be clear the .521 reading is with the connecting rod hooked up. For me .521 is a little high idling at about 1400 Rpm just yse that number as a starting point when syncing.

 

2. It will change the TPS readings but shouldn't throw it way off. Again don't fret the minor changes seems like these bikes are all a little different.

 

3. Sync the idle using the idle air afjustment screws, the connecting rod only needs adjusting when syncing above idle 2-3k rpm.

 

4. Not sure what question 4 is asking but if you are asking about the adjustment screws 2.5mm allen heads. Just use the left side and make sure you back the right all the way out.

 

Make sure that your throttle butterflies are completely closed and both of your choke screws are out of play completely.

You should pop open your airbox tubes and give your TBs a shot or two of carb cleaner. Then start from the beginning.

How is your fuel filter?

Fresh quality Petrol?

 

Seems pretty rare anybody does this process perfect the first time. Focus on setting up the TPS first because the bike should run ok with just the correct TPS setting.

[JBBenson]

All of the above advice is good. I would add that the white knob is for balancing above 3000 RPM, and the bleed screws are for balancing at idle (not an RPM number, but with the throttle fully closed).

 

Although my bike ran really well, I had a lot of trouble holding a smooth idle.

 

I was at the point where I dreaded going for a ride, it would stall out so often. Turns out the carb sync tool I was using was a POS.

 

I made one of these: 

 

http://www.powerchutes.com/manometer.asp

 

My bleed screws ended up at 1.75 out on the left, and .75 out on the right. I was nowhere near these uneven settings.

 

But the gauge doesn't lie, and now my bike idles reliably after warm up. These bikes are really finicky, but when you get it sorted, you will love it.

[docc]

The air bleed screws can also get sooted up. Remove them and clean them, and their holes, with throttle body cleaner (along with the throttle plate edges).

[slowkitty]

To answer your questions

 

1. No, it should go back to near your settings after connecting/disconnecting. Just to be clear the .521 reading is with the connecting rod hooked up. For me .521 is a little high idling at about 1400 Rpm just yse that number as a starting point when syncing.

 

2. It will change the TPS readings but shouldn't throw it way off. Again don't fret the minor changes seems like these bikes are all a little different.

 

3. Sync the idle using the idle air afjustment screws, the connecting rod only needs adjusting when syncing above idle 2-3k rpm.

 

4. Not sure what question 4 is asking but if you are asking about the adjustment screws 2.5mm allen heads. Just use the left side and make sure you back the right all the way out.

 

Make sure that your throttle butterflies are completely closed and both of your choke screws are out of play completely.

You should pop open your airbox tubes and give your TBs a shot or two of carb cleaner. Then start from the beginning.

How is your fuel filter?

Fresh quality Petrol?

 

Seems pretty rare anybody does this process perfect the first time. Focus on setting up the TPS first because the bike should run ok with just the correct TPS setting.

 

Hi,

 

Thanks for the answers. Qn 4 was incomplete, it should be "4. Will disengaging the throttle idle screws on both sides in any way affect the function of the synchronization knob, or the 2 system are linked?".

 

On the syncro rod being off the "correct" setting, I thought that depending how much one thread into the ball joint, surely that would alter the length of the rod and in some way affect the butterfly openings? Hence disconnecting / connecting will introduce some alteration in settings?  

 

There is also some throttle "sticking" that I am experiencing. This also meant that I can never return to the 151 mV that I obtained at first go. Is that normal, or I have to pay attention to some other aspects of the throttle system e.g. cables etc first? I am contemplating removing the throttle bodies and giving them a good clean.

 

Thanks, guys.

[czakky]

The two TBs are connected only by the sync rod. Follow your throttle cable it connects to a cam on top of the left TB.

The idle adjust screws will affect the idle sync. Until this thing is sorted I would just back out the right so it doesn't screw you up.

Another method for synching these TBs calls for backing out Idle air screws 1 turn then syncing at idle using the idle adjust screws. Then using the sync rod for "off idle" syncing.

I had trouble getting a perfect idle and use the right idle stop for a more stable stop for the TBs. If that makes any sense....

 

How far off are your TPS readings when you release the throttle? A few MVs won't matter. Just make sure you give thosr TBs a couple of sprays with a good solvent. Hook up your volt-meter before and after to see if it made a change.

 

Taking out the TBs is a huge PIA. Lets make sure we have this procedure done right first.

 

Also I have an extra TPS if you suspect yours is bad.

[czakky]

Sorry Slowkitty just reread your last post. Yes connecting the sync rod will affect your TPS reading. Thus the 521MV reading. Your TBs need to be open slightly to idle.

[slowkitty]

Sorry Slowkitty just reread your last post. Yes connecting the sync rod will affect your TPS reading. Thus the 521MV reading. Your TBs need to be open slightly to idle.

 

The initial reading was 800 mV when I explored this, with the bike not started.  This was the reading with the syncro knob tweaked previously. The throttle idle screws were virgin and untouched from factory, judging from the paint on the screws.

 

On what you say, shouldn't I attain the 521mV reading only after reconnecting the syncro connecting rod, after getting the 150 mV TPS reading?

 

My trouble seems to be that I can get the 512mV, but the idle is not stable.  How do I get a stable idle?

 

Finally, how often does the Throttle Position Sensor go bad?

 

Thanks.

[JBBenson]

 

Sorry Slowkitty just reread your last post. Yes connecting the sync rod will affect your TPS reading. Thus the 521MV reading. Your TBs need to be open slightly to idle.

 

The initial reading was 800 mV when I explored this, with the bike not started.  This was the reading with the syncro knob tweaked previously. The throttle idle screws were virgin and untouched from factory, judging from the paint on the screws.

 

On what you say, shouldn't I attain the 521mV reading only after reconnecting the syncro connecting rod, after getting the 150 mV TPS reading?

 

My trouble seems to be that I can get the 512mV, but the idle is not stable.  How do I get a stable idle?

 

Finally, how often does the Throttle Position Sensor go bad?

 

Thanks.

 

Make sure the throttles are clean, you can do this while they are on the bike: use q-tips and carb cleaner, take your time. This should help with the sticky throttle. I had the same issue with getting a consistent number when it snapped shut. A good cleaning will solve this.

 

The idle is balanced using the bleed screws. Make a "yardstick manometer" like the above link, this will make it easy. Forget some expensive carb sync tool, this cheap thing is the best I have ever used.

 

I thought I needed a new TPS too, I was tearing my hair out trying to get a steady idle. Get the throttles clean, and remove the left-hand little idle stop screw. Forget about the yellow paint on everything, remove it with a wire brush, Dremel with a wire wheel tip, or a x-acto knife. The Guzzi respects the bravery. Do it.

 

Set the disconnected right-hand TPS baseline at 150mV, set the connected right-hand TPS at around 520mV (using the remaining right-hand little idle stop screw), make the "yardstick manometer", and balance above 3000 RPM using the white knob, and then balance the idle using the bleed screws.

 

It will work.

[czakky]

Consistent idle will depend on how well you balance with idle air by-pass screws. Getting them dead-on is important. Also make sure your bike is warmed up.

 

The TPS commonly goes bad from staying at the same throttle opening for many miles or from turning it too hard when adjusting it. It can be tested by using an ohmmeter and verifying an even progressive rise in resistance across the two outer prongs.

 

Good luck, re-read the procedure and start from the top. You'll have a rip snorting Goose in no time!

[Kiwi_Roy]

To get mine (80K) to idle consistently I use both throttle stop screws.

At 15k I'm sure the linkages are still nice and tight but mine would be ±100 revs relying on just the LH stop

I start with both bodies shut and feel for the screw just making contact using a slip of paper as a feeler, then I wind both in by an equal amount.

[slowkitty]

Consistent idle will depend on how well you balance with idle air by-pass screws. Getting them dead-on is important. Also make sure your bike is warmed up.

 

 

Thanks for the encouragement. Do I need the bike warmed up to find the 150mV and the 521mV? I thought that a cold bike is alright for that. I understand that the throttle-sync needs a warm bike.

 

To get mine (80K) to idle consistently I use both throttle stop screws.

At 15k I'm sure the linkages are still nice and tight but mine would be ±100 revs relying on just the LH stop

I start with both bodies shut and feel for the screw just making contact using a slip of paper as a feeler, then I wind both in by an equal amount.

 

 

May I ask why do you need both throttle stop screws? I read that the right one can be left backed-off, and the left used to adjust. Would not the left just hold the adjustment by itself?

 

Thanks.

 

I am looking to cleaning the throttle bodies as much as I can. trying how to remove the manifolds without removing the airbox, bodies etc.  More fiddling this weekend.

[Phang]

Hi all, I am slowkitty's mate who held responsible for draining the scura battery with multiple starts last Sunday.

 

 

 

 

May I ask why do you need both throttle stop screws? I read that the right one can be left backed-off, and the left used to adjust. Would not the left just hold the adjustment by itself?

 

Kitty, I think a high mileage bike will need the use of right throttle stop screw to take up the slack in the linkages and ball joint because of wear and tear.

 

Phang

[fotoguzzi]

Thanks for the encouragement. Do I need the bike warmed up to find the 150mV and the 521mV? I thought that a cold bike is alright for that. I understand that the throttle-sync needs a warm bike.

 

no you do not need motor warm to set the TPS voltage, it does not even have to be  running.

 

May I ask why do you need both throttle stop screws? I read that the right one can be left backed-off, and the left used to adjust. Would not the left just hold the adjustment by itself?

 

if link rod has no slop you can rely on one stop screw

 

 

I am looking to cleaning the throttle bodies as much as I can. trying how to remove the manifolds without removing the airbox, bodies etc.  More fiddling this weekend.

 

that will be a waste of time, just get to setting the TPS and then off idle sync then balance for idle with air bleed screws.

 

forget the baseline setting of 150mv.. just set the throttle stop screw to contact the plate and adjust the TPS to 525mv or something close.