Will it break the bike!?

The 2009 Road King came with a 103 derby cover but I have no way to tell it it’s a 103 or 96. I’m about to put a tuner on it with canned tune. Can I try 103 tunes without damaging the motor?

Id assume if I try 103 or 96 and if runs like crap, then it’s the other motor.

What do you think?

 

I would ask the company you purchase your tuner from or the shop doing your tuning.

 

I was thinking the same. For now I’m just doing a Vance and Hines Fuelpak. I wonder if they’ll have an answer for me though.

any other thoughts?

 

What canned map? The canned map shouldn't damage the motor. If the tuner is the FP3/4 a few auto tune sessions should bring the tune into a reasonable configuration.

You could also run a compression test which will answer the 103 or 96 question.

 

What numbers would you look for on the compression test to help determine?

 

V & H are very helpful by phone.

 

If motor is stock about 180psi for 96 and 190psi for 103 for a top end in good condition. Don't know how many miles on the motor, how it has been maintained or how it has been ridden so a 103 that has high miles, poor maintenance, etc, could very well read 180psi, so maybe compression testing is not a dependable way to determine displacement. I would check compression anyway, just to have a baseline for future reference. Might even do a leak down.

If the OP went bigger bore, the displacement could be 103 or even 107. We keep guessing but the only way to know the displacement for sure is to pull a head and measure bore and stroke.

EDIT: Thanksk for the correction from rigidthumper; had to edit the VIN comment per his correction. I will stick with the rest of the post.

 

All the RKs in 2009 left the factory with a 96" engine.
What happened after that, is a guess, unless you dissect

 

Put a bore scope down the plug hole, see if there's a number on top of the piston.

 

I would go by Rigidthumper's statement, he's one of the most accurate sources of information here

Flash the 103 tune then run an auto tune session, if the VE numbers drop dramatically then maybe it's a 96, but not a real accurate method any way, sometimes displacement is bumped to compensate for maxing out the VE's

bottom line is give the engine what it wants to run, isn't that the real purpose of tuning