No Device: General question about Spark tables
Stellar HDF Member
Joined: Sep 2009
Posts: 2,114
Likes: 666
Yep, if you never start off from a stop you will never lug it...Suppose some start out at 3000rpm and slip the clutch to keep the load light...no lug.
Bob
Road Warrior
Joined: Mar 2013
Posts: 1,923
Likes: 587
From: Alorton, Illinois
It's a non touring CANBus cal. How much of a difference does it make? Depends if you get there. This can be tested. Roll up to red line in 4th and let it coast down to 2200 or so. I would also pay attention the closed throttle spark table setting, main spark, and what is logged. Then performing the decel test but abort it at say 3000 by getting back on it.
What gear will depend. You want to get a coast without too much engine breaking and enough leverage to get back into it without lugging. I can tell you that a heavier bike seems to go lower in KPA than lighter bikes but cam/ exhaust combo seems to play in as well. Based on decel on a dyno that takes the weight of the bike out of the equation. Based on my opinion of what I have noticed, peaked some interest, and just kept an eye on. Not something I have logged and tracked per say.
Good topic.
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Road Warrior
Joined: Jun 2015
Posts: 1,325
Likes: 140
From: Edinburgh UK
Good pointer, thanks WOC
I am finding higher compression doesn't need quite so much advance in general, sometimes even a degree or so less than the original stock values
Another weirdness I noticed in the Softail 2016 stock map was the idle/warmup 750-1250 rev range was different between the front and rear cylinders.
10ş @1000rpm on the front and (a possibly more normal?) 15ş on the rear - anyone know what that is about?
Possibly keeping the front cylinder cooler than the rear at idle? but why??
I am finding higher compression doesn't need quite so much advance in general, sometimes even a degree or so less than the original stock values
Another weirdness I noticed in the Softail 2016 stock map was the idle/warmup 750-1250 rev range was different between the front and rear cylinders.
10ş @1000rpm on the front and (a possibly more normal?) 15ş on the rear - anyone know what that is about?
Possibly keeping the front cylinder cooler than the rear at idle? but why??
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,929
Likes: 8,033
From: poway
Good pointer, thanks WOC
I am finding higher compression doesn't need quite so much advance in general, sometimes even a degree or so less than the original stock values
Another weirdness I noticed in the Softail 2016 stock map was the idle/warmup 750-1250 rev range was different between the front and rear cylinders.
10ş @1000rpm on the front and (a possibly more normal?) 15ş on the rear - anyone know what that is about?
Possibly keeping the front cylinder cooler than the rear at idle? but why??
I am finding higher compression doesn't need quite so much advance in general, sometimes even a degree or so less than the original stock values
Another weirdness I noticed in the Softail 2016 stock map was the idle/warmup 750-1250 rev range was different between the front and rear cylinders.
10ş @1000rpm on the front and (a possibly more normal?) 15ş on the rear - anyone know what that is about?
Possibly keeping the front cylinder cooler than the rear at idle? but why??
If you increase compression by any amount you will need to back off the timing.. It takes less time to burn the mixture.. Tighter squish will do it also... In cases where there is a leaner burn, the efi will even run the timing further advanced to consume all of the fuel and meet emissions..
I would guess that the timing difference between the front and rear has to do with the number of degrees between firing pulses. Front to rear is 315 and rear to front is 405.. At lower speeds the crank slows less front to back than back to front.. If the cranks is moving faster on the rear cylinder, less fuel is burned when the motor is still cool. More timing on the rear makes lets the rear warm up at a closer speed to the front and burns fuel more completely.. This likely reduces startup emissions.
An example would be an higher compression evo I own.. Early on I ran too much timing and you can't adjust individual cylinders.. First start when cool, it would idle mainly on the front cylinder until it got hot.. Then it idled fine. It was east to tell since it had staggered duals that were pretty loud..
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Road Warrior
Joined: Jun 2015
Posts: 1,325
Likes: 140
From: Edinburgh UK
I had to think about that a couple or three reads ...but that makes sense. So the front power stroke only has to push it around 315 before the rear powers it around further, but that has to last 405 before the front pushes it again - hence the rear is moving faster at the start of the power stroke than the front does on it's.
Perfect sense ...and comes back to that point about you tuner guys listening to the exhaust to tell you what is going on.
I'll never hear anything with my 2-1 ...and lack of said experience, lol
Perfect sense ...and comes back to that point about you tuner guys listening to the exhaust to tell you what is going on.
I'll never hear anything with my 2-1 ...and lack of said experience, lol
Former Sponsor
Joined: Dec 2016
Posts: 77
Likes: 26
From another perspective, 10 degrees makes more heat in the pipe than does 15 degrees of timing. I found that any less timing than is needed makes more heat, not less.
Back in the day, I could turn the timing down on any engine and the head pipes will glow red. The engines run the coolest when the timing is correct, not lower.
Back in the day, I could turn the timing down on any engine and the head pipes will glow red. The engines run the coolest when the timing is correct, not lower.
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Road Warrior
Joined: Jun 2015
Posts: 1,325
Likes: 140
From: Edinburgh UK
I had a look in the HD tuner software and see that they have continued this idea with the M8 engines ...4 degrees lower on the front
As long as it's not too low presumably, and the combustion is still in progress and burns the opening exhaust valve. I presume that would be when you get glowing pipes?
As long as it's not too low presumably, and the combustion is still in progress and burns the opening exhaust valve. I presume that would be when you get glowing pipes?
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