vibration 80-100mph

[johnwesley]

When we first got the bike I went through and replaced the fuel pump, filter, and pressure regulator as well as rebuilt the suspension with new Ikon shocks and fac dampers. The whole bike vibrated so much that I couldn't ride it. After a good TB sync and tune up its much better except at 80mph in 5th or 4th gear, I have a hammering vibration set in mainly at the handlebars. The vibration continues through 100mph. When in 4th the vibration is a higher frequency due to the RPMs. The vibration changes with RPMs and the drive shaft is at a constant rpm at the same speed regardless of engine speed/rpm. The bike only has 35,000 miles on it.

 could someone help point me in the right direction on this?


here's the bike just for pics sake.

[lazlokovacs]

I know I'm in a minority here, but.....

fuel injection

run that engine on carbs and it'll be so much smoother

100,000s miles experience on late model calis both injected and modded by me to run on carbs, there is no contest!

Tried every FI map out there.

And as a disclaimer, I'm not saying that this is the case for every guzzi.

Flame protection hat ON!

[lucky phil]

I know I'm in a minority here, but.....

fuel injection

run that engine on carbs and it'll be so much smoother

100,000s miles experience on late model calis both injected and modded by me to run on carbs, there is no contest!

Tried every FI map out there.

And as a disclaimer, I'm not saying that this is the case for every guzzi.

Flame protection hat ON!

Ok I'll be first. Zero sense in this from a technical perspective.
Because it's a new to him bike with the issue from his day 1 he needs to start with first principles. Cylinder compression would be a good start.

Ciao

[Tkelly]

Ujoint?

[bmc5733946]

I would be sure that TBs are still synched at 3-4000 rpm before I did anything else. This definetly sounds like engine speed stuff, possibly clutch or transmission input bearing, but that's just slinging mud to see what sticks. What happens when you pull the clutch lever at those speeds.

Brian

[chuck peterson]

2x wag’s for a ujoint

I surmise a few seasons unused in a cold garage will eventually form condensation inside the rubber..leading to rust…leading to a scorched ujoint when put back into service

Just guessing…happened twice to me

Turn the wheel really slowly see if there any resistance at certain spots

[chuck peterson]

Swingarm pivot pins off to one side?

[Scout63]

Any vibration at lower speeds?  Check the front and rear tires carefully to make sure that the bead is seated evenly all the way around on both sides. Make sure that the reference line is equidistant from the rim all the way around.

Is the windscreen easily removable?  Maybe try removing it for a test ride.

[johnwesley]

I would be sure that TBs are still synched at 3-4000 rpm before I did anything else. This definetly sounds like engine speed stuff, possibly clutch or transmission input bearing, but that's just slinging mud to see what sticks. What happens when you pull the clutch lever at those speeds.

Brian

Pull in the clutch and it’s smooth as silk at 90

[inditx]

No offense but I’ll be the curmudgeon here and say maybe take it a little slower?
inditx

[chuck peterson]

Is it a big valve cali?

[johnwesley]

No offense but I’ll be the curmudgeon here and say maybe take it a little slower?
inditx

None taken but typically cruise about 5 over. In most places in Texas that’s 80. So I’m there a lot and need the bike to run as it’s suppose to.

[Huzo]

2x wag’s for a ujoint

I surmise a few seasons unused in a cold garage will eventually form condensation inside the rubber..leading to rust…leading to a scorched ujoint when put back into service

Just guessing…happened twice to me

Turn the wheel really slowly see if there any resistance at certain spots

Easy test on that one, take the bike up to the vibration zone then change gears and keep the same speed.
If the vibration stays it’s behind the gearbox, because the driveshaft is still turning at the same speed in the new gear.
If it alters it’s engine RPM related.

[Huzo]

Any vibration at lower speeds?  Check the front and rear tires carefully to make sure that the bead is seated evenly all the way around on both sides. Make sure that the reference line is equidistant from the rim all the way around.

Is the windscreen easily removable?  Maybe try removing it for a test ride.

The test for that is, up to the vibration zone again and pull in the clutch and turn the engine off.
If the vibration goes away it’s in the motor, if not...? Well, you know....

[Turin]

first things I'd check would be the tires, brake discs, and wheel bearings.

[tris]

Cheers Huzo - every day is a school day 

I shall stash that knowledge away for possible future reference

[Huzo]

Cheers Huzo - every day is a school day 

I shall stash that knowledge away for possible future reference

I’ll be in London on Sep 1
Might catch up this time.

[tris]

1st is now in my diary as a reminder/warning - not sure which!

If the stars align lets do it!

Are you Chunnalling to Ferrying to the Continent?
If ferry I hope that P&O have got their act together before you arrive but their issues will be tracking across to the tunnel I'm sure!!

[pressureangle]

Again I'm with Lucky Phil on this one.

It can't be the ujoint if the vibration is attached to RPM. Ujoint is always attached to MPH.

The 'high' MPH may simply indicate the throttle position necessary to uncover a tuning issue.

My 1100 Sport-i shook like a dog crapping a peach seed when I first rode it; two things were huge. Adding a little fuel was the lesser, but the most significant improvement came from very careful balancing of the throttles. So.
1. Adjust your valves very carefully.
2. Be *very careful* to see that both throttle blades are 100% closed. On mine this requires disassembly of the 'choke' mechanism, or it holds the right side open slightly.
3. Close both air adjustment screws.
4. Set your TPS voltage with idle speed screw(s) NOT the air screws
5. Using your carbstix or vacuum gauges, equalize your cylinders at 2500-3500rpm. I've found on mine that higher rpm doesn't change.
6. Set your idle speed with the air screws, keeping the vacuum balanced between cylinders.
7. Re-test balance at 2500-3500. It should not have changed.

That's the procedure I use, and it never fails to amaze me how far things drift from perfect over the course of a few thousand miles.

If there are modifications to exhaust/intake, that may affect your fuel mixture, which is pretty lean as is if stock. Even after mapping my MyECU with known good data, I found that my particular combination likes a little more fuel in the cruising range. I lose a little mileage but it makes the engine enough smoother that I prefer it.

[sdcr]

If none of those ideas work, bring it up to 105.

No offense but I’ll be the curmudgeon here and say maybe take it a little slower?
inditx

[Huzo]

1st is now in my diary as a reminder/warning - not sure which!

If the stars align lets do it!

Are you Chunnalling to Ferrying to the Continent?
If ferry I hope that P&O have got their act together before you arrive but their issues will be tracking across to the tunnel I'm sure!!

Ferry.

[johnwesley]

Again I'm with Lucky Phil on this one.

It can't be the ujoint if the vibration is attached to RPM. Ujoint is always attached to MPH.

The 'high' MPH may simply indicate the throttle position necessary to uncover a tuning issue.

My 1100 Sport-i shook like a dog crapping a peach seed when I first rode it; two things were huge. Adding a little fuel was the lesser, but the most significant improvement came from very careful balancing of the throttles. So.
1. Adjust your valves very carefully.
2. Be *very careful* to see that both throttle blades are 100% closed. On mine this requires disassembly of the 'choke' mechanism, or it holds the right side open slightly.
3. Close both air adjustment screws.
4. Set your TPS voltage with idle speed screw(s) NOT the air screws
5. Using your carbstix or vacuum gauges, equalize your cylinders at 2500-3500rpm. I've found on mine that higher rpm doesn't change.
6. Set your idle speed with the air screws, keeping the vacuum balanced between cylinders.
7. Re-test balance at 2500-3500. It should not have changed.

That's the procedure I use, and it never fails to amaze me how far things drift from perfect over the course of a few thousand miles.

If there are modifications to exhaust/intake, that may affect your fuel mixture, which is pretty lean as is if stock. Even after mapping my MyECU with known good data, I found that my particular combination likes a little more fuel in the cruising range. I lose a little mileage but it makes the engine enough smoother that I prefer it.

weather is supposed to clear up at the end of the week, so I'll get the bike up to temp and check the TB balance to see if it's worked out of sync. thanks for the run-through of your procedure.

[inditx]

None taken but typically cruise about 5 over. In most places in Texas that’s 80. So I’m there a lot and need the bike to run as it’s suppose to.

 

[johnwesley]

I know I'm in a minority here, but.....

fuel injection

run that engine on carbs and it'll be so much smoother

100,000s miles experience on late model calis both injected and modded by me to run on carbs, there is no contest!

Tried every FI map out there.

And as a disclaimer, I'm not saying that this is the case for every guzzi.

Flame protection hat ON!

after studying the P8 ECU operating principles I can see why Carbs are at least more forgiving with vibration. Regardless of the air intake difference between the two cylinders, the ECU is shooting the exact same fuel to both cylinders. the old system doesn't have what is needed to know if one is at a different O2 reading. Whereas the carbs are acting based on each individual cylinder's air intake through the carb. While they are linked to being in the same throttle position it is airflow through the carb that pulls the fuel in. Therefore a dual carb in this application can better meet the inconsistencies between the cylinders.

[lucky phil]

after studying the P8 ECU operating principles I can see why Carbs are at least more forgiving with vibration. Regardless of the air intake difference between the two cylinders, the ECU is shooting the exact same fuel to both cylinders. the old system doesn't have what is needed to know if one is at a different O2 reading. Whereas the carbs are acting based on each individual cylinder's air intake through the carb. While they are linked to being in the same throttle position it is airflow through the carb that pulls the fuel in. Therefore a dual carb in this application can better meet the inconsistencies between the cylinders.

Incorrect I'm afraid, the P8 ecu unlike the P7 ecu has separate cylinder mapping for each cylinder the R/H cylinder expressed as the offset map. Here's a Guzzi V11 Sport fuel offset map expressed as a percentage of the Left main map for anyone interested. There's a good reason EFI is the std these days and it's not because it's inferior to carburettors or makes engines vibrate more.







Ciao

[johnwesley]

Incorrect I'm afraid, the P8 ecu unlike the P7 ecu has separate cylinder mapping for each cylinder the R/H cylinder expressed as the offset map. Here's a Guzzi V11 Sport fuel offset map expressed as a percentage of the Left main map for anyone interested. There's a good reason EFI is the std these days and it's not because it's inferior to carburettors or makes engines vibrate more.







Ciao

No one has said that, just that a carb can make up for differences without needing to write new codes. That’s easy to understand, and is also why the newer FI has that ability built into the system.

[pressureangle]

No one has said that, just that a carb can make up for differences without needing to write new codes. That’s easy to understand, and is also why the newer FI has that ability built into the system.

All you've said here is that if you can't properly sync your cylinders, carburetors will maintain their mixture on their cylinder. That's a lot of work for a band-aid.

[Redrider]

A small patch of thin innertube can isolate the bars. Does the right footrest transmit a scrub/shudder vibration when pulling away from a stop? The GT did and the u-joint failed a couple of weeks later. First lesson learned about shaft drive.

[johnwesley]

The sync was a few lines off when I checked it. Got the sync done yesterday. Today I did a little 450 mile trip around the hills of Arkansas. When I got back it was still slightly off so I fine-tuned it a little bit and now all seems to be decent. I’ll know more when I get a chance to take it out again.



This is at 4500 RPMs. Is the same at 3000 and it idle. Thanks for all the help

[lazlokovacs]

ok, I'll bite

I'm sharing my experience based on over 100,000 miles with each set up, carbs and FI

I can also see no logical reason why the injection should run worse (regardless of map) than the carbs, but that is my experience.

when I have tried to figure out a possible cause, the best I can come up with is perhaps the placement of the injectors on these models is not optimal for combustion/swirl etc??

Also Alpha-N fuel injection is much better suited to bikes of a racing character, and not hugely successful on a bike designed for touring and cruising purposes.

I imagine the very best system would be a MAF FI system but unfortunately that was way out of guzzis pocket at the time.

there are many factors that make an engine happy.

So perhaps it's not a question of FI v Carbs, but just how well does everything come together as a package?

Anecdotally, I swapped my cali from FI to carbs and took my gf for a ride around town. I hadn't told her that I'd changed anything, same bike that she had been on a million times.

After the ride she asked me if I'd improved the suspension! she said going over speed bumps was so much smoother than it had ever been. I guess the improved progession from closed to minutely open throttle positions was affecting how smoothly we got to and over the bumps.

To the OP, hope you get your bike running as you like it and sorry for the thread drift.