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General Category => General Discussion => Topic started by: MikeP996 on April 29, 2026, 10:08:32 AM
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I would like to smooth out the low speed running of my '21 v7 850 special because I often find myself in traffic situations where I'm piddling along at 10-15 MPH for an extensive period and the bike expresses its annoyance with a good bit of bucking/stuttering.
I used a Booster Plug to address this in three other motorcycles I have owned and the BP worked quite well. I don't see a BP available for this bike but searching has revealed a "Rapid Bike Easy fueling device" that claims to address the low speed running. Is there any experience with this device or does experience indicate something else works better?
Thanks!
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I would get a Beetle map to install in your ECU if one is available. Use GuzziDiag to install.
more info at griso.org
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What I gathered when I looked into tuning for my 2022 V7 850 Stone was that the new MIU G4 ECU (CAN-bus) is not (yet) supported by GuzziDiag. Correct me if this has changed since then.
If your bike has not had the ECU updated since new, that would be the place to start. "TECHNICAL COMMUNICATION G_220377_TC_EN" was issued April of 2022 for a new tuning calibration that was meant to fix issues such as what you may be describing. My bike was updated upon delivery, so I never experienced the prior tune that it was meant to address.
I have Agostini exhausts and an UpMap tune for it (UpMap DOES support your V7 850 e5), and with the stock tune or that updated tune the bike is not a super smooth parking lot cruiser, but it is less jerky than many other bikes at low speed (e.g. Ducati Scrambler) where I don't consider that to be much of an issue, especially between 10-15mph. Below that, for low speed maneuvering, (rear) brake and clutch usage help smooth things out.
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Thanks. Seems ironic that my '76 CB400F Honda can trundle along at 12-1500 RPM with nary a hiccup! Of course I realize that it doesn't have to meet Euro 5 emissions. ;)
My two BMWs can almost match it (both have Booster Plugs). Prior to the BPs they were worse than the V7!
No idea what ECU program is in the bike; it was well cared for by the previous owners but don't know if it was ever updated. I guess the only way to know is to take to a dealer ???
It had several mods when I bought it - adjustable front fork cartridges, Mistral slip-ons, KN filter, and that velocity stack thingie so I ASSUME the owner(s) would have ensured the firmware was current.
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I had a quick squizz at the 2021 spare parts manual & it looks like your airbox is the same as that on my early 1TB, so some observations follow:-
By all means, ensure you are running the latest map.
Oil in the airbox from overfilling the engine can get pushed up and into the manifold & inside the throttle body - result - extremely poor running, coughing, spluttering, stalling; all sorts of nasty. The oil also blocks the MAS sensor hole that can be glimpsed (with difficulty) in the floor of the throttle body close to the manifold. Clean the oil away with paper towels AND dose the passageway with MAS sensor cleaner (it's similar to a carbon cleaner, but designed for throttle bodies).
I found the K&N air filter inferior to the paper filter. The oiled filter doesn't appear to strain the particulates as efficiently and also tends to coat the inside of the passageway with a film of oil, which also impedes the operation of the MAS sensor. I suggest you test run another paper filter after cleaning down the passageway as far as you can get with paper towels (likely to come back out dirty), then spray with the MAS sensor cleaner. See if the running improves or not. It should settle down with, say, 100 miles. I suspect there might be an optimal amount of filter oil to have the K&N run effectively, it's just all too easy to overfill it.
Just some thoughts. You can't always deviate from stock & expect no unintended consequences. If you do get those, go back to stock & change one thing at a time & see what happens. After each change re-set the ECU to re-set the learning parameters - leaving the negative terminal on the battery off for about 15 minutes should do it. (Why that works? I don't know, but that's what wiser heads have advised & it seems to work).
By the way, it should be noted that Pete Roper & Beetle don't seem to be fans of those booster plugs that increase fuel flow - they say that they tend to flush fuel into the cylinders, wash away the lubrication & decrease the life of the engine. Just saying. Best to email either of them directly for advice on your specific situation. I tried a booster plug once for a few thousand km - it didn't work for me, so I removed it.
Good luck. I hope you get it running smoothly. These nothing much I dislike more than rough running at idle & low revs.
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Thanks! I don't want to change the map to other than the MG (current) map. Fowlers of Bristol claims to be a MG dealer so they should be able to check the map/update it if it needs it. I'll call them to verify they can do that before riding over there.
I don't see any evidence of oil in the manifold/throttle body but I'll do as you suggest re more thorough cleaning. As far as the KN filter - the previous owner had installed it on the bike and removing it/replacing it with a paper filter won't bother me at all!!
I decided to order the RapidBike Easy Fueling thingie. If it sorts the low speed running, great! If it doesn't, oh well, I've spent more on a pub lunch with the family! I'll report either way. I want to emphasize that the low speed running I'm complaining about does not show up to an annoying extent in what I'd call "normal" riding. But it really got my attention a few days ago when I was in a road construction area and spent nearly an hour alternating between being either stopped or at 10-15 MPH for extended periods.
Again, thanks!!
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Not sure if this has anything to do with your particular issue, but FWIW, if you are experiencing really rough throttle transitions at low throttle angles (i.e., at low speed you open the throttle a bit and nothing happens, then you twist a bit more and the bike lurches forward - what people call snatchy fueling), then the most likely culprit is the EVAP system. You can check this by just clamping off the vacuum hose that runs from the top of the purge valve (behind the left side cover) to the intake manifold. If doing that greatly improves throttle response, then congratulations, you are about 30 min and $0 away from a much better running bike - just perform the well-documented cannisterectomy procedure. I have spent a few thousand dollars on mods to my 2023 V7, and that free mod has had by far the most profound positive effect on the bike.
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I used a Booster Plug to address this in three other motorcycles I have owned and the BP worked quite well. I don't see a BP available for this bike but searching has revealed a "Rapid Bike Easy fueling device" that claims to address the low speed running. Is there any experience with this device or does experience indicate something else works better?
I made my own lamda sensor modifier (aka booster plug). It was cheap and helpful, but later got a programmable ECU. The new ECU was more helpful, but had it's own issues.
Double-click on the photos to get the text: https://www.flickr.com/photos/sign216/albums/72157629649665070/ (https://www.flickr.com/photos/sign216/albums/72157629649665070/)
Joe
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Thanks for the Evap system info! I'll work on that!
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I am of the understanding that the '26 V7's were the first ones with the electronically controlled purge valve. I disabled mine, it made a big difference.
kk
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In the past day or so I've read a bunch of the info re evap system removal and the statements that it helps low speed performance. I'm trying to understand why. I don't see anything in the function of the system that should have any direct effect on engine performance. It's just a vent system.
What am I missing re function of the system that causes low speed running issues? I apologize if this has been covered previously but although I found plenty of info on removal I haven't found an explanation of the system's operation that cause low RPM running in the first place.
I guess what I'm thinking - apparently incorrectly - is that if the evap system is working properly, there should be no impact on running. ?????
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LMFTFY
I guess what I'm thinking overthinking..
Canostomy is one of the first tasks that I undertook on my V7III: I didn't think about it, just done it.
I betya it helped when I trickled between a double line of about eighty cars, yesterday.
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In the past day or so I've read a bunch of the info re evap system removal and the statements that it helps low speed performance. I'm trying to understand why. I don't see anything in the function of the system that should have any direct effect on engine performance. It's just a vent system.
What am I missing re function of the system that causes low speed running issues? I apologize if this has been covered previously but although I found plenty of info on removal I haven't found an explanation of the system's operation that cause low RPM running in the first place.
I guess what I'm thinking - apparently incorrectly - is that if the evap system is working properly, there should be no impact on running. ?????
Well, prepare not to like this post.
Though I do think you sometimes see unintended consequences of emissions standards affecting operation at certain rpm, I also think most people make mountains out of molehills or just flat out fool themselves into thinking something has an affect (good or bad).
Confirmation bias is strong.
I yanked my evap system in my Jackal many years ago because it was huge with dual canisters in each side taking up room I wanted to use. The only result, other than cosmetic, was my garage sometimes smelled from the venting fuel tank.
So I tested it on my B11 and my MkI V7 by clamping off the purge line and I could not perceive any difference in cold starts, hot starts, or running. Maybe I'm just a dull tool when it comes to such subtle perception, but I agree it's usually just a boogeyman that gets blamed when it's not the problem. So much so now that I've installed a happy face sticker on the canister in the V7 to show how happy it is to be there holding vapors between rides.
But then again I feel the same way about signal spoofers. Ok, the spoofer CAN have an actual affect (I guess just like a flooded EVAP can theoretically have), but it's limited and let me explain.
Depending on what signal you're spoofing the ECU can often adjust fuel trim to eventually ignore the spoof (at least if you're still running a map that uses the O2 sensors for feedback).
More importantly a spoofer IS a dumb tool in that it ASSumes that the map is lean everywhere and therefore needs to be "richened up a bit" across the board. Thing is, the map isn't lean everywhere, it's pig rich in places, especially when accelerating, so you do risk running too rich, wasting fuel, and contaminating oil in a lot of use. I'm not predicting catastrophic failures or anything like that, just waste, inefficiency, and potential wear. All of which bother me more than adjusting to an l any small perceived imperfect running condition.
Again, maybe I'm just a dull tool, but for me, it's a well thought out remap or just leave it stock. Same with my EVAP or SAS or...
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I remember Moparnut72 having issues and it cured them for him. I last did a canister job on my 98 and 01 EV's. Since then I have had a 15, 16, 17 and now a 26 sport v7 serries all stock with no run ability issues or reason to change. Same for the 20, 22, 23, 25 V85TT's. I am slowly learning "if it ain't broke, don't fix it".
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I will try to explain this as best I can and what I understand about the system. It has been a while since I did the delete. The evap system on the '26 V7's is different than previous models. I have one of the very early '26's, I was surprised that the dealer I got it from seemed to be one of the very few that had one at the time. It is no longer a passive system. There is a valve with a solenoid that is controlled by the ECU. This is called a purge valve. Under certain conditions which I believe to be low RPM operation the ECU opens the valve. This allows air to be pulled through the canister directly to the intake post throttle body leaning out the mixture resulting in surging. I removed the canister and some of the components. After doing this as advised by the poster who described the reason for and how to do it. On further consideration I would just block off the hose going to the intake. The valve must remain intact with the wiring still attached or the ECU will know the system isn;t functional. Anyway this is what I understand. I believe the reasons and and the methodology were covered in a thread on the ADV forum. It would have been in the V7 850 thread probably in October or November. I will see if I can find it. My 850 still had some surging at low speeds and low gears until it is fully up to operating temps at which point it runs quite well. The conversion was well worth it in my opinion. I had my doubts as I did a canisterectomy on my Audace as per a guy on that forum from So Cal I no longer visit which had absolutely no effect. A Booster Plug helped a little bit on that bike but I think the ECU compensated somewhat reducing it's effectiveness. Anyway sorry for the long diatribe, just relaying my experiences, right or wrong. I hope it helps.
Kk
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I will try to explain this as best I can and what I understand about the system. It has been a while since I did the delete. The evap system on the '26 V7's is different than previous models. I have one of the very early '26's, I was surprised that the dealer I got it from seemed to be one of the very few that had one at the time. It is no longer a passive system. There is a valve with a solenoid that is controlled by the ECU. This is called a purge valve. Under certain conditions which I believe to be low RPM operation the ECU opens the valve. This allows air to be pulled through the canister directly to the intake post throttle body leaning out the mixture resulting in surging. I removed the canister and some of the components. After doing this as advised by the poster who described the reason for and how to do it. On further consideration I would just block off the hose going to the intake. The valve must remain intact with the wiring still attached or the ECU will know the system isn;t functional. Anyway this is what I understand. I believe the reasons and and the methodology were covered in a thread on the ADV forum. It would have been in the V7 850 thread probably in October or November. I will see if I can find it. My 850 still had some surging at low speeds and low gears until it is fully up to operating temps at which point it runs quite well. The conversion was well worth it in my opinion. I had my doubts as I did a canisterectomy on my Audace as per a guy on that forum from So Cal I no longer visit which had absolutely no effect. A Booster Plug helped a little bit on that bike but I think the ECU compensated somewhat reducing it's effectiveness. Anyway sorry for the long diatribe, just relaying my experiences, right or wrong. I hope it helps.
Kk
I get it and good explanation.
I wonder why they only purge at low rpm?
I also wonder if it's true that it actually leans the mixture or by how much.
But as you say the 26 is a different beast.
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I don't know if it is at low rpm or not. I am only guessing at that but it may at higher rpm but it wouldn't be as noticeable. It still doesn't like to be trolled below 2K in 1st or 2nd but who would do that? I sold my Mandello due to age issues and I would have kept my V7lll Special as I liked the bike a lot but I needed cruise control due to two surgeries on my right hand Dupytrens. The new V7 is so much better I am glad I upgraded even if cruise wasn't the issue.
kk
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BUT if the mixture is "leaned" by the purge valve opening to allow vapors to be sucked into the combustion chamber, the O2 sensors would detect that and the ECU should automatically increase the fueling to be at the "correct" ratio - that's its job. Now whether that programmed ratio is right for low speed performance is a different issue but it seems to me that the opening/closing of the EVAP valve should not have any effect on the mixture since it can be constantly adjusted as necessary by the ECU.
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You would think but I am only reporting what I and another guy who brought this up have experienced. It is not a small hose that goes to the intake. I have been unable to find his posts.
kk
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Hose going to manifold goes to valve---------
(https://i.ibb.co/4nxzLpCk/Evap-V7-850.png) (https://ibb.co/4nxzLpCk)
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This morning I temporarily bypassed the EVAP per instructions here and went out for a ride on my '21 V7 850 Special. I couldn't tell any difference in the way the bike acted with the EVAP bypassed. Maybe the effect is different for different model years?
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After testing the EVAP disconnect with no difference, I then installed the Rapid Bike Easy fueling device. Took it out for a ride and was extremely impressed! The low speed issues I disliked are gone. The bike is perfectly happy trundling along in 4th gear at 1200 RPM through the 20MPH speed limits in local towns/villages. The other day, when dealing with similar speeds for extended periods I had to keep the bike in 1st gear with the RPM at 3k to avoid the unpleasantness. For me it was well worth the £150 to gain that smoothness below 3000 RPM. There is smooth power from idle on up.
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After testing the EVAP disconnect with no difference, I then installed the Rapid Bike Easy fueling device. Took it out for a ride and was extremely impressed! The low speed issues I disliked are gone. The bike is perfectly happy trundling along in 4th gear at 1200 RPM through the 20MPH speed limits in local towns/villages. The other day, when dealing with similar speeds for extended periods I had to keep the bike in 1st gear with the RPM at 3k to avoid the unpleasantness. For me it was well worth the £150 to gain that smoothness below 3000 RPM. There is smooth power from idle on up.
I think I see the problem here.
These bikes are not meant to be lugged like that.
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Correct fueling at low RPM eliminates the common complaints about low RPM running, snatchy throttle, hesitation, etc. On my '21 850 the fueling device did what it is advertised to do - produces a much smoother low RPM operation and transition as RPM increases. It's a noticeable improvement over the stock setup. Of course a remap will do the same thing PLUS add some power through the rest of the rev range. Since I'm happy with the bike's power, I didn't see any need for that, I just wanted the increased smoothness at the low end. It also eliminated the "off/on" throttle feel.
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I think I see the problem here.
These bikes are not meant to be lugged like that.
Riding on level or declining ground, that is not lugging. Lugging is making the engine labor under too heavy a load. There is no reason whatsoever that any engine should have problem with correct fueling from idle to redline. My V9 dislike low load situations, and under 15 mph only 1st gear can be used, and even that quickly gets erratic if traffic require constant small speed adjustments. Basically, the bike reacts very abrupt to tiny throttle adjustments when the load is light, regardless of gear. My Virago 1100, which has a higher redline (by 200 rpm, but still higher) can be ridden in top gear at speeds where the V9 is erratic/bucking in third gear. Due to poor fueling, not because it is laboring.
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Riding on level or declining ground, that is not lugging. Lugging is making the engine labor under too heavy a load.
Horse hockey - 20 mph - 1200 rpm - 4th gear = lugging
I wonder why I have no problem with stock fueling on any of my current bikes or an demos/test rides I've had in ages? Simple mechanical sympathy.
Use as intended.
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Horse hockey - 20 mph - 1200 rpm - 4th gear = lugging
I wonder why I have no problem with stock fueling on any of my current bikes or an demos/test rides I've had in ages? Simple mechanical sympathy.
Use as intended.
We will just have to agree to disagree on this :smiley:
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There is literally no load on the engine at 1200 RPM in 4th gear holding speed on level ground. Low RPM/higher gear does not constitute "lugging;" the load on the engine determines if the RPM/gear/throttle position will cause the engine to struggle ("lug.")
It's totally a function of current emissions requirements that have made low RPM stumbling and abrupt on/off throttles quite common. If you are comfortable defeating the emissions with an aftermarket product, the bikes can operate smoothly from idle up.
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It's totally a function of current emissions requirements that have made low RPM stumbling and abrupt on/off throttles quite common.
Couldn't agree more.
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So all this angst is about…………
Traffic jams?
I mean, the only place all this fuel controversy takes place is in stop and go clogs?
Just to put a crazy tangent to this…
I believe a Convert would solve all this…chuckle eheheheh!
I believe all this horse patoo is about emissions requirements for clean air, not better running
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There is literally no load on the engine at 1200 RPM in 4th gear holding speed on level ground. Low RPM/higher gear does not constitute "lugging;" the load on the engine determines if the RPM/gear/throttle position will cause the engine to struggle ("lug.")
The only way there is no load is if you are coasting.
If you're using the engine to move the bike, there's a load.
And because you're in 4th and not 2nd you've removed a lot of mechanical advantage the lower gearing gives the engine so the load is greater per revolution.
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The only way there is no load is if you are coasting.
Being that pedantic.. there is always a load due to friction and reciprocating mass. Whether there is significant load that can't be overcome by inherent torque, is another matter. :blank:
Just for reference: I do fairly frequently cruise through (20mph/30mph) villages in the lowest (ratio) gear possible, though more like 4th/5th, on my V7III. The 5-speed 750 Breva just about managed 4th @ 20mph but that was 'unfair' to it and kinda lumpy. Not possible on the Monster 600!
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All those gears are in there for a reason!
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Hose going to manifold goes to valve---------
(https://i.ibb.co/4nxzLpCk/Evap-V7-850.png) (https://ibb.co/4nxzLpCk)
If you want to experience the difference, reach in and unplug hose & cap manifold. All the BS goes away.
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Well, as I said, for my 21 v7 850, eliminating the EVAP connection had no effect that I could notice. Maybe I'm not a good "noticer!" :)
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Then it's time for an UpMap device.
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This morning I temporarily bypassed the EVAP per instructions here and went out for a ride on my '21 V7 850 Special. I couldn't tell any difference in the way the bike acted with the EVAP bypassed. Maybe the effect is different for different model years?
Did you plug the hose from the valve to the manifold? If you did that and saw no effect, then yes, you can eliminate the EVAP as the source of your issue.
Someone above wrote that they thought 2026 is the first year with an electronic purge valve. That's not correct. My 2023 Stone has one. The diagram for the entire EVAP system is on a sticker under the seat. Mine is different from others that are also quite recent. Maybe it was a change from E4 to E5?
On my bike the change in fueling with the EVAP delete was *profound*. Like, no rider could miss it. Going from nearly unrideable at in-town speeds to perfectly well behaved.
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"On my bike the change in fueling with the EVAP delete was *profound*. Like, no rider could miss it. Going from nearly unrideable at in-town speeds to perfectly well behaved. "
That's what I was hoping for but no joy. :( Yes, I plugged the hose from valve to manifold. But I was pleased that the Easy Fueling device produced that result - perfectly well behaved at in-town speeds.