Insight on synchronizing throttle bodies?

[rfkicker2000]

Fred, thanks for the info!

My manual for the R6 says vac at idle (1250~1350rpm) should be 18cmHg. I tried getting it therewith my previous syncs but it wouldn't go without the engine bogging down. Maybe I adjusted the screws in the wrong direction or too quickly, not sure.

I'm wondering if I should turn all the screws in until they bottom out, then turn #3 out until it reads 18cmHg, then turn the rest out until they read 18 as well. I had a feeling tb #3 had something to do with the EFI. I'm wondering if the reading on #3 NOT being 18cmHg is what's causing the computer to put the wrong amount of fuel into each cylinder, thereby causing vibes?

To Fred and others, I did buy the Morgan Carbtune. Great tool....no mercury to worry about. =)

 

[SovietRobot]

Fred, thanks for the info!

My manual for the R6 says vac at idle (1250~1350rpm) should be 18cmHg. I tried getting it therewith my previous syncs but it wouldn't go without the engine bogging down. Maybe I adjusted the screws in the wrong direction or too quickly, not sure.

I'm wondering if I should turn all the screws in until they bottom out, then turn #3 out until it reads 18cmHg, then turn the rest out until they read 18 as well. I had a feeling tb #3 had something to do with the EFI. I'm wondering if the reading on #3 NOT being 18cmHg is what's causing the computer to put the wrong amount of fuel into each cylinder, thereby causing vibes?

To Fred and others, I did buy the Morgan Carbtune. Great tool....no mercury to worry about. =)

I highly doubt the computer actually reads specific vacuum pressures.
18cmHg is more of a guide than a rule.
If you noticed while adjusting, the bike runs a lot different at different pressures, even if they're all even. The idle also changes at different pressures, and at some you'll be unable to lower/highten the idle speed.

Fuel and throttle body sync have nothing to do with eachother. Throttlebody sync is about how much air the butterfly valves let in. An improper sync means uneven turbulent airflow, which causes the vibrations.

+1 on the morgan. Best $90 spent.

 

[Fred]

I highly doubt the computer actually reads specific vacuum pressures.

I know for a fact that it does.

Fred

 

[Fred]

I'm wondering if I should turn all the screws in until they bottom out, then turn #3 out until it reads 18cmHg, then turn the rest out until they read 18 as well. I had a feeling tb #3 had something to do with the EFI. I'm wondering if the reading on #3 NOT being 18cmHg is what's causing the computer to put the wrong amount of fuel into each cylinder, thereby causing vibes?

That would be a move of desperation, and I wouldn't do it unless all else has failed.

If you're having trouble getting #3 cylinder to the target vacuum, then get it close and synch the other three to match. Then reset your idle, as it will have changed. Then see if you can adjust #3 again. Then synch again. Then reset idle again. Idle adjustment and the synch screws both affect idle in in different ways, so when you adjust one, it's good to go back and check the other.

Another thing to consider is that sometimes the screws can be counterintuitive. You close them, vacuum increases, until the engine bogs down, then vacuum decreases again. If you open them, vacuum will decrease, but then the engine will rev up, increasing vacuum again.

One last note, these screws are extremely sensitive. Try this. While synching, put the screwdriver on one of the screws and apply a little downwards pressure onto the screw head. Look at the reading for that cylinder. Now remove the pressure from the screwdriver and watch the reading change. Pretty cool, eh? So once you've got a screw where you like it, remove the screwdriver to double check that it's really good.

Hopefully you can work your way back to a good running bike by working through the procedure a couple of times.

Fred

 

[rfkicker2000]

Another thing to consider is that sometimes the screws can be counterintuitive. You close them, vacuum increases, until the engine bogs down, then vacuum decreases again. If you open them, vacuum will decrease, but then the engine will rev up, increasing vacuum again.
Fred

This is exactly what happened to me when I started to close the screws. I love the comment about them not being intuitive, and that pressure on the screw changes vacuum. Only experience can tell you those things. Should've listened to my dad and NOT touched that 3rd screw!

One last question: Many say to check for vacuum leaks as this will give inaccurate readings. I can't think of any other sources of vacuum leak other than the connection of throttle body to the engine. Would a vac leak be terribly obvious -- like a hissing sound that was noticeable when the bike was idling?

I'll let you know how it all turns out. If nothing else, this has been a great learning experience so thanks again! Me -> :squid:

 

[Fred]

You wouldn't head a vacuum leak over the sound of the engine and the regular intake sounds. The way to test for one is to spray propane, carb cleaner or starting fluid around the joints. When you spray this fuel near the leak, it'll get sucked in and the engine will burn it. You'll hear the revs change.

On bikes, these leaks are usually due to degraded rubber between the head and carbs/throttle bodies. Your bike is so new that this isn't going to be a problem. You're not likely to have a leak unless you've pulled the throttle bodies out of position.

Fred

 

[gt89stang393]

I actually bought parts to make my own sync tool to try. If that doesn't work then I will buy a tool. Money is tight right now.

 

[SovietRobot]

I know for a fact that it does.

Fred

Okay, but what does it do with these readings?

 

[Fred]

Okay, but what does it do with these readings?

The MAP value is used in the fueling calculation. I don't know if the FZ6 uses Speed Density, Hybrid Alpha-N, or a blend of SD and regular Alpha-N. You can try asking Yamaha, but they probably won't give you the source code for their ECU.

Here's a good starting URL if you want to understand what's happening in your bike's computer. Be warned, you can read about this stuff for days at a time and still not be done.
How MegaSquirt ® Works

 

[rfkicker2000]

On bikes, these leaks are usually due to degraded rubber between the head and carbs/throttle bodies. Your bike is so new that this isn't going to be a problem. You're not likely to have a leak unless you've pulled the throttle bodies out of position.

Other than pulling the airbox off and on a few times, I don't see any reason why there would be a leak. I checked the rear motor mounts tonight and they did tighten up a bit to 33ft-lbs. Doubt that'll totally cure the vibes but I'm sure it can't hurt. The fronts were already tight.

Plan on doing the tb sync again this weekend following your procedure. Thanks again for the help!

 

[rfkicker2000]

Plan on doing the tb sync again this weekend following your procedure. Thanks again for the help!

Ok, following your procedure above, I did the sync a bunch of times at operating temp (175 - 190F). Attached are the pics from the Carbtune indicating that the vacuum is as close to 18 as I can get it. The first pic is just for reference. The rest are shots of the gauge readings. They bounced around a bit between 16 and 18 so I took several for you to see.

I had to turn the screws all the way out, then turn tb 3 in by 1/4 - 1/2 turn each time and match the others until I got it close to 18. The engine did bog down a bit as I turned them in and I had to turn the idle up a bit to get it to factory spec of 1250 rpm. Still, the engine sounds fine when it is idling, no loping or sputtering and it revs up cleanly, no sputtering there either. When I hold it to 4 or 5k rpms, the vac settles out at the same point across all cyls so it must be in sync.

Still getting the vibes though so at this point, I'm out of ideas. Unless something dropped in one of the cylinders when I changed the plugs and scored the cylinder badly, I don't know what could be causing this. I would figure if that happened though, I'd be getting some serious blow by and blue smoke -- which I'm not.

 

[dantrigg]

...Still getting the vibes though so at this point, I'm out of ideas. Unless something dropped in one of the cylinders when I changed the plugs and scored the cylinder badly, I don't know what could be causing this. I would figure if that happened though, I'd be getting some serious blow by and blue smoke -- which I'm not.

You may have unintentionaly hit the end of one or more of the spark plugs and changed the spark plug gap when you installed them. Perhaps you didn't get the wires tight one or more of the sparkplugs This could be the source of your vibration.

 

[rfkicker2000]

This bike uses wire harnesses that clip into place. I was considering going back down to the plugs again to have a look. However, the shop said they were fine. Wondering if I should believe them though considering they told me the bike was supposed to vibrate. lol.

 

[pkoosa]

This bike uses wire harnesses that clip into place. I was considering going back down to the plugs again to have a look. However, the shop said they were fine. Wondering if I should believe them though considering they told me the bike was supposed to vibrate. lol.

that or even put back in the old plugs.

 

[rfkicker2000]

Is it possible cylinders could be misfiring or not firing at all even though the carb syncer shows all cylinders appear to be drawing vacuum? Seems to me if one or more were fouled out or not firing at all, the carb syncer would make this apparent. Also, I touched each header pipe and they were definitely hot.

 

[pkoosa]

Is it possible cylinders could be misfiring or not firing at all even though the carb syncer shows all cylinders appear to be drawing vacuum? Seems to me if one or more were fouled out or not firing at all, the carb syncer would make this apparent. Also, I touched each header pipe and they were definitely hot.

it's possible. the engine is just an air pump. the rod and piston are still in motion even if the plug for one cylinder isn't firing. putting back the old plugs will at least give some insight if it's the new plugs.

 

[FZ1inNH]

Well to rule out any suspicion of one of the cylinders, do a compression test on all four and be sure they are in spec and in doing so, you can check the plugs as well as the gap on each.

 

[rfkicker2000]

Unfortunately, I tossed the old ones. Suppose I'll need a new set if the ones that come out are shot. Waiting for Fred to chime in with his take on the matter.

 

[Fred]

Is it possible cylinders could be misfiring or not firing at all even though the carb syncer shows all cylinders appear to be drawing vacuum? Seems to me if one or more were fouled out or not firing at all, the carb syncer would make this apparent.

It wouldn't show up on the synch tool. Even misfiring, the cylinders will pull a vacuum during the intake stroke.

From your pictures, you appear to have the bike very nicely synched. So I'd start looking elsewhere.

If the pipes are all getting hot, then that's probably not the problem. You can double check this by putting a bit of WD-40 on each header while the bike is cold. Start it up and let it idle and see if one pipe takes longer to dry out.

I agree with whoever said it, doublechecking the plugs and their gaps is a really good idea at this point. You may have a plug or wire problem that will only appear during larger throttle openings, causing a cylinder to cut out. (The resistance across the spark gap increases as cylinder pressure increases, so more throttle can "blow out" a weak spark.)

So, check plug condition, plug gap, and make doubly sure that the spark plug wires are fully connected.

Fred

 

[rfkicker2000]

That's true, it's a vac tool not a spark tool. I guess that's what you get for a being a rookie at working on sport bikes. I'll check the plugs and report back. Thanks!