DYNO - less than pleased
#12
03-01-2011, 10:55 PM
Join Date: Sep 2005
Location: Phoenix, AZ
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#13
03-01-2011, 10:56 PM
75HP/90TQ is about what you should expect from a tuned Stage I 96"er. However, it should not have any decel pop; ussually indicates a lean condition. Check head pipe connections and gaskets; check muffler to head pipe connection. If all are tight, it's the tune. You should not be able to make a well tuned TC pop on decel if you try. Particulalry with the SERT. I question the tuners experience and capability.
More than likely ... but only the guy tuning it really knows.... the dyno guy had to richen up the mixture at certain points to compensate for predetonation. If you removed the original pipes you will be more prone to afterfire since you no longer have cat sections and have reduced back pressure.Pops...often referred to as engine decel pop is where a bit of fire blows past the exhaust valve and ignites a fuel rich exhaust mixture.
An approach to minimize pop is to cut fuel from the injectors during decel from the RPM where pops start to the RPM where they stop. But you can NEVER totally eliminate it.
It's normal to get some engine afterfire on aggressive throttle and decel. Its easy to do....to say its not reveals either a very passive riding style or just lack of riding experience....or just a lack of mechanical acumen.
Late model 96b engines run very lean...with bias towards advanced timing...all intended only to meet EPA standards....they often require timing retard and enrichment particular if you pursue stage 1 nods.
You will need to see if your ECM allows for decel fuel cutoff....start with 2400 rpm to 1700 rpm cutoff ....don't overdo the dry interval so that you end up with a dry cylinder that will result in a lean hot mixture on the compression cycle....I compensate for this with a slightly longer duration upon throttle up.
This is one of the problems with dyno runs....you may achieve a tune (although not in this case) that produces bragging rights hp/tq numbers....but leaves the bike with annoying real world driveability issues...in this case pop/afterfire. Also...you turn your bike over to someone who will do who knows what to your bike and in too many cases won't sit down and explain exactly what he did or let you participate in the dyno session...a good dynoman will tell you what he did and why....or ask you to attend the session you are paying for...then ask you to ride the bike for an hour or so and report back if you have any issues....ie, pinging, dead spots or pop/afterfire then he will address these issues BEFORE you pay and ride away. If you did not get that level of service....don't go back there...but rather find someone who cares enough...or better yet....get an ECM that you can tune yourself. Learn how to do it....and take care of it yourself....its not magic....just a little reading and a little work will suffice.
If a bike is tuned on the edge...with aftermarket pipes ....I can make it pop....without really trying.
#14
03-01-2011, 11:01 PM
#15
03-02-2011, 12:46 AM
Road Warrior
Finally some good analysis... the curves look pretty good for a fairly stock Stage I setup. You could get a ThunderMax or some other tuner, and one of the settings (TMax) is the Decel Fuel Cutoff, which works great if the decel pop really bugs you that much. cpiad is right on the money...
Roger
Roger
#16
03-02-2011, 01:08 AM
Elite HDF Member
Good grief....that is just not so...it does not mean a lean condition...quite the opposite.
More than likely ... but only the guy tuning it really knows.... the dyno guy had to richen up the mixture at certain points to compensate for predetonation. If you removed the original pipes you will be more prone to afterfire since you no longer have cat sections and have reduced back pressure.Pops...often referred to as engine decel pop is where a bit of fire blows past the exhaust valve and ignites a fuel rich exhaust mixture.
An approach to minimize pop is to cut fuel from the injectors during decel from the RPM where pops start to the RPM where they stop. But you can NEVER totally eliminate it.
It's normal to get some engine afterfire on aggressive throttle and decel. Its easy to do....to say its not reveals either a very passive riding style or just lack of riding experience....or just a lack of mechanical acumen.
Late model 96b engines run very lean...with bias towards advanced timing...all intended only to meet EPA standards....they often require timing retard and enrichment particular if you pursue stage 1 nods.
You will need to see if your ECM allows for decel fuel cutoff....start with 2400 rpm to 1700 rpm cutoff ....don't overdo the dry interval so that you end up with a dry cylinder that will result in a lean hot mixture on the compression cycle....I compensate for this with a slightly longer duration upon throttle up.
This is one of the problems with dyno runs....you may achieve a tune (although not in this case) that produces bragging rights hp/tq numbers....but leaves the bike with annoying real world driveability issues...in this case pop/afterfire. Also...you turn your bike over to someone who will do who knows what to your bike and in too many cases won't sit down and explain exactly what he did or let you participate in the dyno session...a good dynoman will tell you what he did and why....or ask you to attend the session you are paying for...then ask you to ride the bike for an hour or so and report back if you have any issues....ie, pinging, dead spots or pop/afterfire then he will address these issues BEFORE you pay and ride away. If you did not get that level of service....don't go back there...but rather find someone who cares enough...or better yet....get an ECM that you can tune yourself. Learn how to do it....and take care of it yourself....its not magic....just a little reading and a little work will suffice.
If a bike is tuned on the edge...with aftermarket pipes ....I can make it pop....without really trying.
More than likely ... but only the guy tuning it really knows.... the dyno guy had to richen up the mixture at certain points to compensate for predetonation. If you removed the original pipes you will be more prone to afterfire since you no longer have cat sections and have reduced back pressure.Pops...often referred to as engine decel pop is where a bit of fire blows past the exhaust valve and ignites a fuel rich exhaust mixture.
An approach to minimize pop is to cut fuel from the injectors during decel from the RPM where pops start to the RPM where they stop. But you can NEVER totally eliminate it.
It's normal to get some engine afterfire on aggressive throttle and decel. Its easy to do....to say its not reveals either a very passive riding style or just lack of riding experience....or just a lack of mechanical acumen.
Late model 96b engines run very lean...with bias towards advanced timing...all intended only to meet EPA standards....they often require timing retard and enrichment particular if you pursue stage 1 nods.
You will need to see if your ECM allows for decel fuel cutoff....start with 2400 rpm to 1700 rpm cutoff ....don't overdo the dry interval so that you end up with a dry cylinder that will result in a lean hot mixture on the compression cycle....I compensate for this with a slightly longer duration upon throttle up.
This is one of the problems with dyno runs....you may achieve a tune (although not in this case) that produces bragging rights hp/tq numbers....but leaves the bike with annoying real world driveability issues...in this case pop/afterfire. Also...you turn your bike over to someone who will do who knows what to your bike and in too many cases won't sit down and explain exactly what he did or let you participate in the dyno session...a good dynoman will tell you what he did and why....or ask you to attend the session you are paying for...then ask you to ride the bike for an hour or so and report back if you have any issues....ie, pinging, dead spots or pop/afterfire then he will address these issues BEFORE you pay and ride away. If you did not get that level of service....don't go back there...but rather find someone who cares enough...or better yet....get an ECM that you can tune yourself. Learn how to do it....and take care of it yourself....its not magic....just a little reading and a little work will suffice.
If a bike is tuned on the edge...with aftermarket pipes ....I can make it pop....without really trying.
EDIT:
Lots of tuning gurus willing to help on this forum and lots more on Harley Tech Talk forums.
Last edited by HoggyMtnBreakdown; 03-02-2011 at 01:11 AM.
#17
03-02-2011, 05:01 AM
Elite HDF Member
I'll voice my 0.02 here as there is a decell enleanment feature thats built in the program. In order to get rid of it you need to have that changed. Just fatten that up a little and it will be fine. The #'s are in the ballpark for what you had done. The change in decell enleanment won't have any other effect to how the bike runs. Very simple and effective. I have a SERT and have no issues.
#19
03-02-2011, 12:12 PM
#20
03-02-2011, 12:13 PM
I have a pretty noob question which is along the lines of this topic.. aside from being Loud and ..well.. pretty fun when some dumb broad is about to step into the street on her cell phone .. ... "Oh you want to not pay attention where you're going? RAPAPAPAPPPPAPAPPP.. yeah."... does it damage the engine in any way?