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V9 Backfire

D

dformell

Just got it firing!
GT Contributor
Joined
Sep 14, 2021
Messages
6
Location
Dearborn Heights, MI.
2017 V9 Roamer backfires on deceleration when bought stock new and backfires with modifications. Modifications are:

secondary air system removal kit installed
Carbon canister and tip valve removed
Agostini mufflers sans baffles
computer re-flashed

I know that an exhaust leak at the header-to-engine connection will cause backfiring as well as the muffler-to-header connection; a lean mixture will also give the same result. I've done the following:

checked exhaust connections - all are tight - no blow-by observed on pipes
vacuum connections - sprayed carb. cleaner on them, no change in idle
adjusted valves
checked for cracks in header pipes - nada
spark plugs show that the bike is running a little lean

Interestingly a met a guy with a 2017 V9 bobber bought from the same dealer and he has the same issues as me, stock/modified the bike backfires on deceleration. Has anyone else with a V9 experienced these issues? Other than using a richer running computer map I'm at a lose on what to do. Any kind of input would be greatly appreciated.
 
I used to have backfires on my 2017 V7 III, but that went away once the ECU was flashed with one of Todd's maps. Now she runs like a dream.
 
Hello neighbor!

In order to meet worldwide emmissions standards, they are set very lean in the factory fueling.

You cannot run Agostinis with the baffles removed and not expect this. It will only become amplified.

You need to look at fueling solutions offered by GTM in the STORE tab and have Todd build you a good fueling map.

It sounds like you got taken on your remap.

If you get Todd's fueling setup, you will get rid of that situation and have a motorcycle that runs correctly and sounds like a dream.

That's your solution!

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Last edited:
dformell said:
2017 V9 Roamer backfires on deceleration when bought stock new and backfires with modifications. Modifications are:

secondary air system removal kit installed
Carbon canister and tip valve removed
Agostini mufflers sans baffles
computer re-flashed

I know that an exhaust leak at the header-to-engine connection will cause backfiring as well as the muffler-to-header connection; a lean mixture will also give the same result. I've done the following:

checked exhaust connections - all are tight - no blow-by observed on pipes
vacuum connections - sprayed carb. cleaner on them, no change in idle
adjusted valves
checked for cracks in header pipes - nada
spark plugs show that the bike is running a little lean

Interestingly a met a guy with a 2017 V9 bobber bought from the same dealer and he has the same issues as me, stock/modified the bike backfires on deceleration. Has anyone else with a V9 experienced these issues? Other than using a richer running computer map I'm at a lose on what to do. Any kind of input would be greatly appreciated.
Click to expand...
Who reflashed your ecu?
 
No. The message just got much sharper.

My next question is was this something you purchased and loaded yourself?

If so, Todd gives excellent technical support if you contact him through whatever email your paperwork told you to.

Now, if he (deformell) is having an issue with his setup from Todd, then this is not the proper venue for getting assistance.

He has an issue that needs to be communicated with the CONTACT links or whatever designated contact address he was given. That would make sense.

Todd does not read every post made here. It is illogical to assume so.

He would be reading all day.

I’m sure that there is something not correct here but there certainly is no latitude for wild speculation.

Todd is known for his fueling solutions and many of us have them, myself included and they are first rate.

I’m sure that once you get your communication established correctly through the proper venue, then Todd will help you and get it squared away.

He always does.
 
Last edited:
scottmastrocinque said:
No. The message just got much sharper.

My next question is was this something you purchased and loaded yourself?

If so, Todd gives excellent technical support if you contact him through whatever email your paperwork told you to.

Now, if he (deformell) is having an issue with his setup from Todd, then this is not the proper venue for getting assistance.

He has an issue that needs to be communicated with the CONTACT links or whatever designated contact address he was given. That would make sense.

Todd does not read every post made here. It is illogical to assume so.

He would be reading all day.

I’m sure that there is something not correct here but there certainly is no latitude for wild speculation.

Todd is known for his fueling solutions and many of us have them, myself included and they are first rate.

I’m sure that once you get your communication established correctly through the proper venue, then Todd will help you and get it squared away.

He always does.
Click to expand...
Definitely. I can back this up
 
dformell said:
2017 V9 Roamer backfires on deceleration when bought stock new and backfires with modifications. Modifications are:

secondary air system removal kit installed
Carbon canister and tip valve removed
Agostini mufflers sans baffles
computer re-flashed
Click to expand...
Thanks guys. @dformell - please email us @ info @guzzitech.com
So this has been gone over 1000x.
Things like this are IMPOSSIBLE to diagnose via the internet. My maps are extremely well proven. I have heard hundreds of times that all of what you list has been done, but in the end, something is always amiss. I recommend triple checking your list by doing everything again. Also, and most often missed in the re-flash PDF & video, is the MANDATORY TPS reset. If you did it post re-flash, do it again, and once/month or minimally every few as a minimum. I'm only posting here in hopes that others will read this (though not very likely). My maps can occasionally have a small amount of closed throttle popping, but most all had service done by the owners, and when I saw them in person, they all had problematic set up including valve lash, tip/evap improperly done and/or exhaust leaks or cracked exhaust parts. So what did you set the valves to? Send all info to the email above.
 
Not to get in the way but…

I hope you get it sorted out now, but if you cannot get it figured out on your own, my professional workshop is 1 hour away from you and there are my personal 5 Moto Guzzi’s sitting on my shop floor including the best running Stelvio with an open Mistral can and Todd’s full setup on it.

I don’t believe you will find anybody around this region like me or with my skills and experience with Moto Guzzi motorcycles.

If you cannot eventually find the source of your mistake, I’m sure that I can.

My first double check would be the intake valve gap.

Your high-flowing exhaust is certainly causing the afterburn conditions on deceleration but your fuel intake may be compromised with an improper valve lash setup.

Take heart and know that right here, Mayakovsky said he got his totally resolved on his bike like yours. You will also.

Good Luck to you!
 
Last edited:
Thank you everybody for your input. The bike backfired when it was stock. I know another with the same bike, same model, same year and his bike has the same issues; the bike backfires stock or modified. I contacted Todd, he said he could write a new map but he seemed to think it was a vacuum leak caused by me when I removed the tip valve. I tested for vacuum leaks, sprayed carburetor cleaner on vacuum connections while engine was running - no change in idle. After doing other tests I emailed Todd with the results, he told me that he didn't have time to diagnose my problems or read long emails. I thanked him for the tips and apologized for the long winded email.
 
I know you have checked most of the things, but I would check two more things.
1. Oil in the airbox.
2. I don't know how tight the Agostini mufflers are at the header connection. I have Zard Zuma and they are a bit loose, so I put on some high temp. RTV.
 
I would have you do a simple test.

Ride the motorcycle at speed and abruptly shut off the throttle or just let it instantly snap back to home position. I'll bet you have dramatic backfiring.

Now, do the same thing, but actually uniformly and smoothly, roll off the throttle to the home position. I bet you won't have any or significantly much less.

Try it and let us know your results. It will be very interesting and useful information.
 
Thank you everybody for your input. Scott & Subin per your suggestions Here's the results:

A little bit of oil at the bottom of the airbox.
Abrupt throttle shut-off, high R.P.M. = a lot of backfiring.
Gradual throttle shut-off, low R.P.M. = little or no backfiring, usually no backfiring.

I look forward to your responses!

Regards,
Dan
 
dformell said:
Thank you everybody for your input. Scott & Subin per your suggestions Here's the results:

A little bit of oil at the bottom of the airbox.
Abrupt throttle shut-off, high R.P.M. = a lot of backfiring.
Gradual throttle shut-off, low R.P.M. = little or no backfiring, usually no backfiring.

I look forward to your responses!

Regards,
Dan
Click to expand...

This is exactly what I expected.

The abrupt closing of the throttle, causes a sudden and non-linear radical change in the air - fuel ratio, and facilitates the backfiring.

While rolling off of the throttle smoothly, creates a uniform and linear reduction in the air - fuel ratio.

Have you done the TPS resets as instructed by Todd? This critical component step cannot be over-emphasized.
 
Thanks Scott.
@dformell - send me an email if it persists beyond all things stated above. Every time I revise my maps, it's a tail-chase until I finally return to the one I originally send. Again, they are pretty well proven, though not perfect for every bike on the planet, as the factors are immense for fuel requirements. Wish I could fit my dynamic fuel kit to these models.
 
Thank you for the input guys. It's been almost a year since I did the re-flash, I would like to think that I did the TPS reset but it probably wouldn't hurt to do another re-flash just to be sure. I heard somewhere - probably here - that it's good to do a seasonal re-flash every year. Does that sound right? At the risk of being redundant, you guys have been very helpful and I really appreciate it.
 
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