If instead of going to 107ci somebody stayed at 103ci and did all else as in the Fuel Moto 107 big bore kit, would there be much difference? I got asked the question. But I'm not sure how to answer it. The guy has the 103 cylinders and pistons and wants to avoid spending the extra bucks on the 107 parts.

 

I don't have dyno numbers, but all else being equal, I can't see a 4 ci increase in displacement (less than 3%) giving much in the way of real world power differences. Unless you're only interest is in bragging rights and showing off dyno reports I'd say the 103 with the proper mods and tuning will give more than good results. IMHO only.

 

A properly built and tuned 103" will run with a 107" all day long.

 

That 4 cu in could mean a lot depending on the build differences but all else being equal you would not notice a difference.

 

Got a 103,originally a 96,in my '10 Road King,just with 103 cylinders,ported heads,hi comp pistons.255 cams,hi flow air and exhaust. It will walk away from a SE 110 CVO,that's all I know.

 

These are the size differences in cc`s. The hp/tq differences with mods are debatable. I would check with the vendors here to get their opinions.

88 cu in (1,449 cc), 96 cu in (1,584 cc), 103 cu in (1,690 cc), 110 cu. in. (1,803 cc)

 

to make a 103 be the same as you are referring to here about the 107 (remember when going to the 107 build you are going with pistons that will have more compression), you are going to change the pistons. If you are going this deep, then why not go ahead and change the jugs as well. You will not be adding much more costs (because you are going to have the same amount of cost in labor) and you will get a few more cubic inches.


all that being said, you might see the difference on a dyno chart between a 103 and 107 with EXACTLY ALL the same mods and tuned by the same guy (who knows what he is doing). But in seat of the pants, probably not so much.


With what few mods I have done (cams / exhaust / AC ), I ran a CVO 110 Ultra this past summer. Light to Light. I got the jump on him and stayed ahead of him the whole way (I could see his front tire the whole time).


the Key to me for power is in compression and the heads (porting). Of course when all else is equal, There is No Replacement for Displacement. In other words, the more CI, the better.

 

2 inches per cylinder is too small to feel a difference. If using the 103's saves some money do it.

 

again, the only price difference will be in the price to have the jugs bored or swapped out. All the rest of the costs will be the same. I can't see the price of having the jugs bored would be that much in regards to the total price of all the other work done.

 

Want a 107, buy a S&S motor. That would be a big difference.