Caming The 103
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
I do agree with you on this one. The one thing I have problems with on PV is being able to tell when maxed out at wot. The drive ability is usually pretty easy to get right via trial and error or looking at a log tune. The hard part is how much timing is the right amount at WOT. Not talking about pinging or detonating. Under wide open throttle you start loosing HP with too much timing long before you start pinging.
Road Warrior
Joined: Apr 2009
Posts: 1,258
Likes: 114
From: Jackson, Ohio
I don't know about you guys but I cannot hear worth a crap anymore so I depend on reviewing the log to see where spark knock started retarding the timing. I'm not one for over doing it on timing as I only use Harley's cams and their timing values on their base maps are close although once you add fuel where needed, you can sometimes get away with just a little more adding timing.
I can get a lot more performance out of the other features of the SEPST such as accel enrichment, VE tables, etc. vs. messing with timing.
I can get a lot more performance out of the other features of the SEPST such as accel enrichment, VE tables, etc. vs. messing with timing.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
I just did a little reading and the total timing for a big twin is 35 degrees and the start timing is 5 degrees. So these things still time up more or less like a V8. You can just tune out individual knock events.
And the more I read the more confused I become. Depending on who writes up the article depends on the recommended total timing and is anywhere from 28 degrees to 41 degrees. Some guys time there motors the old school way like I did and others say no no, set total timing here to a fixed value, and others say set it by timing running over 1/8th course mile at WOT for best time if you don't have a dyno. It appears the twinkie accepts a wide range timing without getting too upset about it. Probably the best way is with a dyno but other methods appear to work just fine.
And the more I read the more confused I become. Depending on who writes up the article depends on the recommended total timing and is anywhere from 28 degrees to 41 degrees. Some guys time there motors the old school way like I did and others say no no, set total timing here to a fixed value, and others say set it by timing running over 1/8th course mile at WOT for best time if you don't have a dyno. It appears the twinkie accepts a wide range timing without getting too upset about it. Probably the best way is with a dyno but other methods appear to work just fine.
Road Warrior
Joined: Apr 2009
Posts: 1,258
Likes: 114
From: Jackson, Ohio
I just did a little reading and the total timing for a big twin is 35 degrees and the start timing is 5 degrees. So these things still time up more or less like a V8. You can just tune out individual knock events.
And the more I read the more confused I become. Depending on who writes up the article depends on the recommended total timing and is anywhere from 28 degrees to 41 degrees. Some guys time there motors the old school way like I did and others say no no, set total timing here to a fixed value, and others say set it by timing running over 1/8th course mile at WOT for best time if you don't have a dyno. It appears the twinkie accepts a wide range timing without getting too upset about it. Probably the best way is with a dyno but other methods appear to work just fine.
And the more I read the more confused I become. Depending on who writes up the article depends on the recommended total timing and is anywhere from 28 degrees to 41 degrees. Some guys time there motors the old school way like I did and others say no no, set total timing here to a fixed value, and others say set it by timing running over 1/8th course mile at WOT for best time if you don't have a dyno. It appears the twinkie accepts a wide range timing without getting too upset about it. Probably the best way is with a dyno but other methods appear to work just fine.
Depending on base maps for specific cams, you should see pre established timing tables and also should be able to see a graph.
Last edited by scj; Jun 11, 2014 at 04:14 PM.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
Yes I am but I visualize it like the timing curve on a distributor and I set it up that way then tuned out the knock events. I advanced the total timing until I had knock events. I thought I backed off two degrees but the more I think about it, it was probably 3 degrees. It's been a couple of years since I set up the timing tables.
Elite HDF Member
Joined: Apr 2007
Posts: 3,766
Likes: 16
From: Roseville, CA
I don't know about you guys but I cannot hear worth a crap anymore so I depend on reviewing the log to see where spark knock started retarding the timing. I'm not one for over doing it on timing as I only use Harley's cams and their timing values on their base maps are close although once you add fuel where needed, you can sometimes get away with just a little more adding timing.
I can get a lot more performance out of the other features of the SEPST such as accel enrichment, VE tables, etc. vs. messing with timing.
I can get a lot more performance out of the other features of the SEPST such as accel enrichment, VE tables, etc. vs. messing with timing.
Road Warrior
Joined: Apr 2010
Posts: 1,648
Likes: 37
From: Monroe, Louisiana
Seem to have gotten off on timing tables. The 255 cams are the only cams I have come across that require real close timing or they will ping. If interested look at a SEPST map for a 14 air cooled touring and the timing maps for them are pretty much optimized. Much better than the 13 and earlier. I have done the old school way for years. Problem was all you had was the initial timing and the timing curve with weights and springs. Drag raced for many years and have modified distributers to set at 40 degrees to launch and have them back off to 32 degrees at 8000 rpms. Didn't have tuners and stuff like the bikes do. You can change every 250 rpms and every 10% load or throttle position. The stock timing maps except the 14's are far from being optimized regardless of add ons. There is a good bit of performance gains to be had by maximizing the timing, particularly below 2500 rpms. Not much if any to be had above that. I know of three of the maps I built have been dynoed and they have not touched the timing maps at all. I build the maps because I enjoy it and have nothing against a GOOD dyno tune. Have seen plenty that were not. With the match up of the right parts for a setup it isn't that difficult to make work. Surprising sometimes how some folks think bigger and louder is always better and the more it lopes the faster it will run. When they get blown away by a well setup stage 1 they can't figure out how that happened.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Road Warrior
Joined: Apr 2010
Posts: 1,648
Likes: 37
From: Monroe, Louisiana
Do you have dyno charts or drag slips to prove this? Very much the way we did it with old hotrods was advance the timing until you started pinging then back it off a couple of degrees. Pretty much what I did tuning my motor. I honestly don't know but I do know this method has worked for a long time on a lot of motors.
Road Warrior
Joined: Apr 2009
Posts: 1,258
Likes: 114
From: Jackson, Ohio
Hell, I cannot hear anything but the intake and the exhaust and I run my bikes very quiet.