vibration 80-100mph

[johnwesley]

I find two different methods of balancing the tb, one says to close the air bleed screws and the balance at 3500 and then use the air bleed to balance idle. The other says to open air bleed to one turn then balance at 3500 and the use the throttle stop to balance at idle. Which one seems correct? If it was carbs no way would you balance with air bleed. 

[pressureangle]

I find two different methods of balancing the tb, one says to close the air bleed screws and the balance at 3500 and then use the air bleed to balance idle. The other says to open air bleed to one turn then balance at 3500 and the use the throttle stop to balance at idle. Which one seems correct? If it was carbs no way would you balance with air bleed. 

The TPS voltage always has to be in the right place first. So the RH throttle has a 'fixed' position at idle. This TPS position should not be enough to idle at speed without adding some air from the airscrew.
The only way to be certain the LH butterfly is in the same position is to begin with both sides fully closed. So my method equalizes butterfly position, then locates TPS position, then accounts for the minor differences in airflow (Valve adjustment, intake port differences, etc) by moving the LH butterfly slightly. When that's all done, your idle speed can only be corrected with the air screws.
At the end of the day, if you're balanced at idle, 2000, and 3000, it's working.

[johnwesley]

The TPS voltage always has to be in the right place first. So the RH throttle has a 'fixed' position at idle. This TPS position should not be enough to idle at speed without adding some air from the airscrew.
The only way to be certain the LH butterfly is in the same position is to begin with both sides fully closed. So my method equalizes butterfly position, then locates TPS position, then accounts for the minor differences in airflow (Valve adjustment, intake port differences, etc) by moving the LH butterfly slightly. When that's all done, your idle speed can only be corrected with the air screws.
At the end of the day, if you're balanced at idle, 2000, and 3000, it's working.

Thanks for that 

[johnwesley]

Went through and set it all up, closed throttle screws backed out and linkage disconnected. Closest I could get was 162mv. Reattached everything, opened air screws to 1 turn from seated, then set the idle screw for 500mv. Next balanced idle. Double checked 3000 rpm amd it was still good. Took it out and much smoother throughout and pulls better in the low and middle rpm. Even the Guzzi shudder is mellowed.

Now I have a new issue through and it just started after setting the tb up. It back fires at closed throttle once rpm is getting close to idle and decreasing speed. Backfires constantly and if I let it continue the I get a loud backfire. Seems I have something out of whack here. 

I’m all ears 

[lucky phil]

Went through and set it all up, closed throttle screws backed out and linkage disconnected. Closest I could get was 162mv. Reattached everything, opened air screws to 1 turn from seated, then set the idle screw for 500mv. Next balanced idle. Double checked 3000 rpm amd it was still good. Took it out and much smoother throughout and pulls better in the low and middle rpm. Even the Guzzi shudder is mellowed.

Now I have a new issue through and it just started after setting the tb up. It back fires at closed throttle once rpm is getting close to idle and decreasing speed. Backfires constantly and if I let it continue the I get a loud backfire. Seems I have something out of whack here. 

I’m all ears

Have you set the valve clearances? Have you had the injectors professionally cleaned? Did you remove the air screws and clean all the gunk off them and the same with the seats inside the throttle body? I'd recommend a compression test as well. What's the CO set at?


Ciao

[pressureangle]

Went through and set it all up, closed throttle screws backed out and linkage disconnected. Closest I could get was 162mv. Reattached everything, opened air screws to 1 turn from seated, then set the idle screw for 500mv. Next balanced idle. Double checked 3000 rpm amd it was still good. Took it out and much smoother throughout and pulls better in the low and middle rpm. Even the Guzzi shudder is mellowed.

Now I have a new issue through and it just started after setting the tb up. It back fires at closed throttle once rpm is getting close to idle and decreasing speed. Backfires constantly and if I let it continue the I get a loud backfire. Seems I have something out of whack here. 

I’m all ears

Idle at 500mv? Someone with stock ECU needs to step in here, I don't recall that being the standard.
Typically an idle backfire (as opposed to a misfire) happens when raw fuel is introduced to the hot exhaust. That can only happen if one cylinder is very rich, or misfiring badly. One reason I adjust everything with the idle air screws closed is because I don't know that the air they allow in comes at a position which allows for flow over the fuel spray pattern, and could lead to poor mixture and puddling at idle. My MyECU idles at 157mv, which is as closed as the 'choke' mechanism allows; the airscrews are out about 1-1/2 turns to bring the idle speed up to 1100. I'm wondering that with your TPS at 500mv, you don't have the right side open way farther than the left. That begs the question how it may be so if you are balanced through the range. Need more data and input from stock ECU adjusters.

[johnwesley]

I need to add this: it only does it at slow speeds with closed throttle. I can't make it backfire at speed. I have run it up to high rpm in 4th and closed the throttle letting it decelerate with the engine. so that's going from 85mph in 4th down to 40mph and never even a pop or spit. so this must be a just off idle thing. Also at idle it randomly coughs back through the TB. now the bike wasn't doing this before. matter of fact I had it running really smooth and nice. then I told a friend about it and he had a different way of syncing and set the air bleed at 1.5 turns. I thought maybe this could be even better and that's when this new low rpm closed throttle low-speed backfiring started. I tried going back to where it was set with no improvement.

[pressureangle]

I need to add this: it only does it at slow speeds with closed throttle. I can't make it backfire at speed. I have run it up to high rpm in 4th and closed the throttle letting it decelerate with the engine. so that's going from 85mph in 4th down to 40mph and never even a pop or spit. so this must be a just off idle thing. Also at idle it randomly coughs back through the TB. now the bike wasn't doing this before. matter of fact I had it running really smooth and nice. then I told a friend about it and he had a different way of syncing and set the air bleed at 1.5 turns. I thought maybe this could be even better and that's when this new low rpm closed throttle low-speed backfiring started. I tried going back to where it was set with no improvement.

Here's what I'd do. Put a half pint of Marvel Mystery Oil in with a full tank of gas, and ride the tank out on roads that don't require much idling, and the faster the better; what you're trying to do is clean the intake ports and valves of any residue that affects airflow. After the couple hundred mile throttle run, check the TB balance to see if it's been changed by the cleanup. Adjust the valves carefully and retest.
An exhaust gasket leak can cause popping in the exhaust on deceleration, but that doesn't sound like what you have.

[nsmith]

This newest problem sounds a lot like my 2001 Calif. spec. A few years back the ol girl got a rough running at a certain throttle position, no matter gear or speed. About 5000 rpm. replacing the TPS fixed that strait away. But that being said it has a closed throttle hiccup, if they get that cleared up the fuel mileage goes down the crapper. Kind of a either or thing, So I let it be a pest at closed throttle and enjoy the ok fuel mileage. 

[Tom H]

Directions for the TB adjustment:

https://archive.guzzitech.com/EVTuneup-Jeff_B.html

Hope this helps.
Tom

[johnwesley]

Directions for the TB adjustment:

https://archive.guzzitech.com/EVTuneup-Jeff_B.html

Hope this helps.
Tom

Thanks for that! I have been doing it that way, but that page had a link for bikes of my old school FI. Those instructions made a whole lot of since because you start from base and work your way up. Disconnect the linage from both TBs and the set idle and balance the with the individual idle controls to 800 rpms. The adjust the left carb balance screw until the linkage drops on. Double check sync and then bring idle up to 1200 with air screws and balance from there with the air screws. I ass/u/me that makes up for some flow difference in the individual heads/cylinders. That’s meticulous balancing allows me to back up if I get off a bit and make sure nothing changed. Which I did once. It all good and running now. I would not have found that if you hadn’t of sent that link, thanks again.

Here is a link to the method that also outlines the details of what each part of the fuel injection does. I printed in and put it in the manual.  https://dpguzzi.com/efiman.pdf

[Tom H]

efiman is very good, but can confuse easily.

Good that you seem to have it sorted out!!

Tom

[johnwesley]

A little pic of keeping the goose from getting to hot.