I recently upgraded my switchback from a 103 to a 107, with fm flat top pistons, and woods 777 cams, the heads, throttle body and injectors are still stock.* wheni ordered my parts I also got my new map from them. my bike runs great,* although I've noticed that when watching the adaptive fuel trims, they very from around 85% to 112 %.* *so I figured I'd run the auto tune basic to try cleaning up the ve tables a little bit.* after a short run using the auto tune, I hit the export learned values button, and got a message saying some of thee values exceed the 125 limit. and it asked did i want to scale the values or cap them.

my question is this,* the fuel moto tune has the engine diplacement at 117 already, by hitting the scale button the pv 2 wants to increase displacement to 124.* is this a bad idea? should i just hit the cap* value button ?

* looking at the ve tables for the auto tune session with the displacement at 124, I still have a hand full of cells at 110-120 range. is this an indication of needing bigger injectors?


bear with me, I'm new to tuning. I've only ran a few auto tunes on my bike and they were all with the stock engine, with air cleaner and exhaust.

if it matters any my air cleaner is a kuryakyn street sleeper 2. and i'm running a d &d fatcat with a louvered baffle.

 

You want the CI big enough to keep your VE's under 127.5. My 103 Triglide Cylinders bored to 105 due to out of round cylinders and new pistons/rings/GMR 577 cams needed CI of 120 to keep VE's under 127.5. Its just a measure of how much air at the different RPM/loads your motor is pumping. You don't need bigger injectors. You don't want to go bigger than you have to with CI though as some of the other tables in the tune will get out of whack like Decel enleanment, Accel enrichment, cranking fuel etc. I had to take my cranking fuel table down at higher temps as it was getting to much fuel and taking longer to start.

 

you want to cap those values, your cubic in should match 107 with stock head you have no big air flow which o2 sensors are you using stock or wide band?those map that they give you are about 10 percent correct, the bike will run but will perform better after it put on a dyno and tuned correctly .

 

It is not uncommon in a strong 107 build to have the displacement constant end up in the 120's or even 130's, it is about getting a high enough ceiling on the VE table which is simply a theoretical representation of the airflow model. You will need to select cap/scale based on how many VE cells you have near/at the high limit of 127.5. If you have a large cluster of cells at 127.5 you may likely need to scale when using AT or if tuning manually raise the displacement constant (and level the rest of the table). You can also use the Charge Dilution Effect (CDE) tables in a specific RPM region to help flatten the table's out, CDE is active below approx 60Kpa, to lower the VE you will lower the CDE value by a given %, note you can also use this table to raise VE as well.

To determine if your injectors are large enough you will use the following equation: IDC = RPM * IPW / 1200, or an easier option when using Power Vision is to use the Injector Duty Cycle channel under datalog that allows you to monitor/log Duty Cycle, you want to keep this below 95%.

 

thank you jamie for clearing that up that was not the info i was giving by a couple techs at dynojet until i got a hold of ken peters. he is the guy that i have had the best success with he has been sick for a week finally got him tonight a he cleared up the same info my Ve were running at max and they told e prior to cap, ken set it up as 117.5 and i did one auto tune session and i had to scale again the VE maxed out over 125. will ride more tomorrow and try to another session done.

 

Good Day to everyone. I am very new to the HD world and would love some wisdom and advise. My dad always told me learn from others mistakes it has taken me years to figure that one out. Any way. My Fiance has a 2012 Heritage 103 with 2000 miles and i would like to play with it some. Gonna put V & H long shots on it with a Kuryakyn Mach 2 breather. I am thinking very serious about a tuner. Is it recomended or do i just take it to Harley and have them hook it up to there computer. If a tuner what does everyone recomend. Any good feed back on the V & H FuelPak
Thankyou so much for your time and thoughts.
We plan on doing alot of riding this summer already put 1000 miles on it in the last mo.
Thanks again Shawn

 

welcome from york pa....take a minute and post in the new member forums. I recommend you call Fuelmoto USA and talk to them. They have a lot of experience from stage 1 to 117 builds. Then you can search here and see what others are doing.

 

Subscribed. Thread tools not working for me.