M8 metallic noise when opening throttle
#21
05-23-2022, 07:02 AM
Outstanding HDF Member
I recently got some gas at a local station (not Top Tier) and decided to try their 91-octane versus to Shell 93-octane (Top Tier) I usually run. PINGING on acceleration was almost immediate, especially at lower rpm. Bought some Lucas octane booster and the pings stopped. Ran through the tank and filled with my normal Shell 93 and no pings. Simple: use higher octane gas and supplement when you can only get the 91.
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90anlu92 (05-23-2022)
#22
05-23-2022, 07:39 AM
It's my opinion that Harley tunes their engines just on the edge of pinging for the peak horse power and torque then relies on the knock sensors to keep it under control. This probably works fine in most conditions but the "plink" comes as the ambient temperature and humidity reach a certain point.
I could be wrong but it is possible the tuner used the default timing table and adjusted the fuel and air mixers. This is what happened when I had my Twin Cam tuned. I would talk to the tuner to see if they can fine tune your timing tables. They could use knock events on recorded runs to fine tune the timing tables in the appropriate ranges.
These days I'm not looking for peak performance so I'm not afraid to sacrifice a little power by pulling some timing off the tables for something that runs a little better when it's 100f out. My primary use for my bike is long range touring. As I said above, I'm not too concerned with the occasional "plink", but one day my obsessive compulsive side will make me do something about it.
I could be wrong but it is possible the tuner used the default timing table and adjusted the fuel and air mixers. This is what happened when I had my Twin Cam tuned. I would talk to the tuner to see if they can fine tune your timing tables. They could use knock events on recorded runs to fine tune the timing tables in the appropriate ranges.
These days I'm not looking for peak performance so I'm not afraid to sacrifice a little power by pulling some timing off the tables for something that runs a little better when it's 100f out. My primary use for my bike is long range touring. As I said above, I'm not too concerned with the occasional "plink", but one day my obsessive compulsive side will make me do something about it.
IMHO, the factory tune is done to get the best out of 93 octane which some states have. Then the knock control is designed to retard spark when it detects knock, which will happen under load with less octane. You will still get a slight ping though. In my experience it takes about 1 oz of Lucas octane boost per gallon of gas to notice a ping reduction.
Remember, octane does not add power, but it allows the motor to develop more power without pre-detonation. As such, lower octane fuel, will result in slightly less performance as knock is detected and the spark retarded yo reduce the knock And consequently reduces power.
Remember, octane does not add power, but it allows the motor to develop more power without pre-detonation. As such, lower octane fuel, will result in slightly less performance as knock is detected and the spark retarded yo reduce the knock And consequently reduces power.
After chasing this identical issue since late 2020 I’d first like to say this is probably the most constructive discussion I’ve seen here on the topic so thanks to all for that.
Couple of observations in the case if my 2020 107.
In stock configuration when new, the bike would lightly ping/rattle consistently through the rpms when accelerating the least bit “aggressively”.
I always run name brand 91, usually Exxon/Mobile because that’s what’s available. Shell 93 where available.
I tried adding 2oz (one bottle) of Lucas octane booster per six gallons, which they advertise boosts octane level “3 points for 4-6 gallons” . Did this periodically even after adding a Powervision tuner and running a new tune after datalogs were sent to Fuel Moto. The octane booster at that concentration had no impact on pinging whatsoever. I haven’t tried two (or three) bottles per trigeezer’s recipe for one ounce to one gallon. I may do that.
It wasn’t till I was on a trip last fall around 11,000 miles on the bike where
I recall first hearing the “tink tink”. If memory serves, I needed to hard accelerate in heavy traffic in warm weather from maybe 2500 -2800 rpms through fifth into sixth gear to 85 mph on an expressway ramp that I first heard it. Wondered if it was rocks hitting the inside of the front
fender, till it did it on the return trip identically, and very occasionally will do that in similar riding conditions.
Interstingly, the consistent ping/ rattle (like “castanets“, think flamenco dancer for us old farts) when accelerating seems to have largely diminished.
One interesting point, when I sent data logs to FM their observation was that any knock events they could see in the logs where considered “normal” and they were surprised that I could even hear them.
Also, I can’t say for sure if I was ever able to log the “tink tink” events last fall when I was adding the tuner.
ETA: I had the two clutch side spark plugs out last week and it’s pretty safe to say the bike is not running lean.
Couple of observations in the case if my 2020 107.
In stock configuration when new, the bike would lightly ping/rattle consistently through the rpms when accelerating the least bit “aggressively”.
I always run name brand 91, usually Exxon/Mobile because that’s what’s available. Shell 93 where available.
I tried adding 2oz (one bottle) of Lucas octane booster per six gallons, which they advertise boosts octane level “3 points for 4-6 gallons” . Did this periodically even after adding a Powervision tuner and running a new tune after datalogs were sent to Fuel Moto. The octane booster at that concentration had no impact on pinging whatsoever. I haven’t tried two (or three) bottles per trigeezer’s recipe for one ounce to one gallon. I may do that.
It wasn’t till I was on a trip last fall around 11,000 miles on the bike where
I recall first hearing the “tink tink”. If memory serves, I needed to hard accelerate in heavy traffic in warm weather from maybe 2500 -2800 rpms through fifth into sixth gear to 85 mph on an expressway ramp that I first heard it. Wondered if it was rocks hitting the inside of the front
fender, till it did it on the return trip identically, and very occasionally will do that in similar riding conditions.
Interstingly, the consistent ping/ rattle (like “castanets“, think flamenco dancer for us old farts) when accelerating seems to have largely diminished.
One interesting point, when I sent data logs to FM their observation was that any knock events they could see in the logs where considered “normal” and they were surprised that I could even hear them.
Also, I can’t say for sure if I was ever able to log the “tink tink” events last fall when I was adding the tuner.
ETA: I had the two clutch side spark plugs out last week and it’s pretty safe to say the bike is not running lean.
Is there some way for me to check the logs at home or do I need some sort of advanced computer tech to do that?
I recently got some gas at a local station (not Top Tier) and decided to try their 91-octane versus to Shell 93-octane (Top Tier) I usually run. PINGING on acceleration was almost immediate, especially at lower rpm. Bought some Lucas octane booster and the pings stopped. Ran through the tank and filled with my normal Shell 93 and no pings. Simple: use higher octane gas and supplement when you can only get the 91.
#23
05-23-2022, 08:10 AM
Seasoned HDF Member
I see you are running Powervision.
This requires WinPV software which Dynojet provides to run on a Windows PC to send and receive tunes and datalogs to the tuner (Fuel Moto in my case), so I believe you could run and look at your data logs if your were so inclined. I view it as above my desired pay grade, so I “have people” for that, being Fuel Moto through whom I bought my Powervision.
Your posts answer a long running question I’ve had, and that is doing an engine build like you did doesn’t seem to escape the quirks (as I view them) of the M8’s ECM. Or maybe they are features, not bugs. All I know is the '95 EVO I just sold, while not nearly as fast, sure didn’t have these confounding issues.
Last edited by gonemad; 05-23-2022 at 08:18 AM.
#24
05-23-2022, 08:20 AM
I think this is the first you’ve mentioned your engine being built beyond a stock “slightly upgraded” 114, so it will depend on which tuning software the builder/tuner used. I’m out of my depth on what all is necessary to install and tune a big bore kit.
I’m running a Powervision tuner which requires WinPV software running on a Windows machine to send and receive tunes and datalogs to the tuner (Fuel Moto), so I believe I could look at my logs if I was so inclined. I view it as above my desired pay grade, so I “have people” for that, being Fuel Moto through whom I bought the tuner.
I’m running a Powervision tuner which requires WinPV software running on a Windows machine to send and receive tunes and datalogs to the tuner (Fuel Moto), so I believe I could look at my logs if I was so inclined. I view it as above my desired pay grade, so I “have people” for that, being Fuel Moto through whom I bought the tuner.
#25
05-23-2022, 09:12 AM
Seasoned HDF Member
#26
05-23-2022, 10:26 AM
#27
05-23-2022, 10:49 AM
Seasoned HDF Member
One has to look at more than just static compression, the correct corresponding cam and tuning all contribute to a cylinder pressure that works.
Last edited by OldMike; 05-23-2022 at 10:53 AM.
#28
05-23-2022, 10:54 AM
Seasoned HDF Member
Why not call the dyno place and explain what is happening. I don't study tuning or timing so can't help but maybe they can easily adjust your tune. Looks like you have a relatively good amount of torque starting early which is probably good but might need a timing adjustment to compensate.
#29
05-23-2022, 11:40 AM
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RocketyMan (06-02-2022)
#30
05-23-2022, 01:45 PM
Seasoned HDF Member
Mine behaves as his does and mine were never turned off. I was heading up an incline on the interstate in the western NC mountains a few weeks ago at 75mph in a headwind and had to roll harder into the throttle to maintain. The knock started and stopped and I could hear and feel the timing being dialed back the instant the “tink tink” stopped. And it’s always just two distinct tinks. Like a two rocks hitting the inside of fender. Very weird to me.
Last edited by gonemad; 05-23-2022 at 02:19 PM.