Donny Petersen says new HD'S are running rich!
Grand HDF Member
Joined: May 2006
Posts: 3,636
Likes: 1,208
From: Ohio
Not sure why anyone would spend $20K on a bike and then change the pipes and AC and NOT change the fuel management to save a few hundred bucks. You will void your warranty and likely cook your top end. Good luck with that...
Maybe Donny P. can rebuild the top end for ya after its cooked...
Maybe Donny P. can rebuild the top end for ya after its cooked...
Cruiser
Joined: Jan 2010
Posts: 101
Likes: 0
From: Alberta Canada
I have the highest respect for both Donny Peterson and Jamie Long, and as far as this subject goes they are both right. What's wrong here is the context of the original so called quote by Donny Peterson. If you have read his books and articles, you must put all the material together not one sentence in an article. Unlike Jap bikes, that you can line up ten of the same models and dyno them and only end up with about a 1% difference in the results, doing the same with Harleys you would get around a 5% difference in the results. Good or bad Harley does not build to as tight a tolerance as other brands.
That said I have read lots of articles that state you can throw pipes and an air cleaner on Harleys and not have to tune. Are they right, yes and no. Consider the 5% variable some may be fine others are going to be lean, but none will be rich, that's impossible. Better flow in and out, same fuel settings, leaner AFR period. The only way to know is to dyno and get AFR figures or gently ride the bike with new plugs, note performance and then read the plugs. I still wonder what the AFR would look like at certain RPM levels and transition points.
Will the ECM possibly be able to compensate for the changes, maybe. The problem is it will only reset it's self back to the original 14.7 to1 AFR and that's to lean. Adding a tune of some sort will address this lean condition and make the bike run cooler, smoother and perform better over all.
If Donny Peterson states that the 2009 HD's run richer, I believe him. I also believe he would be the first to tell you to check and be sure AFR are right after changing parts. Jamie Long is also correct in that even if the ECM compensates for the change it's still to lean, and it could be dangerously lean in certain areas..
That said I have read lots of articles that state you can throw pipes and an air cleaner on Harleys and not have to tune. Are they right, yes and no. Consider the 5% variable some may be fine others are going to be lean, but none will be rich, that's impossible. Better flow in and out, same fuel settings, leaner AFR period. The only way to know is to dyno and get AFR figures or gently ride the bike with new plugs, note performance and then read the plugs. I still wonder what the AFR would look like at certain RPM levels and transition points.
Will the ECM possibly be able to compensate for the changes, maybe. The problem is it will only reset it's self back to the original 14.7 to1 AFR and that's to lean. Adding a tune of some sort will address this lean condition and make the bike run cooler, smoother and perform better over all.
If Donny Peterson states that the 2009 HD's run richer, I believe him. I also believe he would be the first to tell you to check and be sure AFR are right after changing parts. Jamie Long is also correct in that even if the ECM compensates for the change it's still to lean, and it could be dangerously lean in certain areas..
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Grand HDF Member
Joined: Jun 2008
Posts: 4,012
Likes: 298
From: Central Fl
I really don't have a dog in this fight but I do have a question. How many heat damaged pistons has anyone seen? In spite 0f all the talk about burned pistons, valves or whatever how many have actually seen any damage. I worked in the parts dept at an HD dealership and never once heard of or seen any damage from heat. I do know for a fact of 08 TC 08s running SE a/c and pipes with no stage 1 download or tuner at all. I have ''heard'' that ecm's can do small adjustments on their own. Take it for what it's worth.
Cruiser
Joined: Mar 2009
Posts: 158
Likes: 0
From: Austin, TX
I suppose when Dynojet comes out with the LCD unit for the PCV (already have one for the PC III) you can just hook up the wideband O2 sensors and read the AFR right on the screen. WOT, cruise, whatever. Yea, an expensive way to get the info, but other than measuring AFR with the O2 sensors, or on a dyno (still measuring the exhaust), i don't see another way to know the actual AFR on any individual bike.