I looked around but didn't see a thread like this:

I'm going to add some displacement to my 08 Fatbob and wanted a little positive steer. I understand that bigger = more power. The questions I have are:

Cost vs performance gain?
How much of the stock components can I keep?
Will the bottom end need to be done as well?
What all will need to be replaced?
Do the "kits" have everything I need?

It seems that a 107 is about as big as you can go on stock parts from what I've read and it's not that much more expensive than a 103. I'm leaning towards the 107...any ideas?

Have you done the heads yet? That is where the big gains are! Welding the crank is always a good idea if you are looking at going over 100/100.

i was thinking the same...i read that 103 is the best way to go,
if you want for the motor to last for many many years...but, the
1584 ( 96 ) is still new. will it last as long on a 107 or 110....

THAT IS A QUESTION.....

I'm leaning towards a 103" kit with about 10.0-1 pistons (we get 94 oct. here) and not sure about cams, have read 255's are a good choice for the 2000-5000 rpm range?? Not looking to make a race bike, but want more passing/uphill power..

The 103 offers the most bang for the buck. Add some good cams and you you will be on your way.

There is a wealth of knowledge on this site. Most guys really know what they are talking about, I am not one of them. I am very happy with my SE 103 and Andrews 37H cams. It runs strong and pulls much more than stock. I am getting it tuned this week and looking to forward to seeing where I am at. I wanted to start with the displacement and will do more head work this winter.(always need something to do when it starts to **** rain everyday)

I chose the 103 and 37 cams because I new I could do all the labor pretty easily, I don't like anyone else to touch my bike.

I have read great stuff about these guys....
http://www.gmrperformance.com/

Tweakin...I cant wait to ride your scoot next weekend....(IT better be tuned)....LOL just kidding.

He is correct on the 103 and others said the same thing. In terms of bang for the buck....avoid the 110. Several will tell you that a strong 103 will outperform the 110 easily. As far the going on up to 107...I would have to compare numbers to know what I would truly gain over the 103. As far as what you can and cant keep that can be a tough question without know what is inthe kit you buy etc. Look fo the kits that include the whole 9 yards. Jugs, heads, cams, pistons, pushrods, lifters, and even the gaskets as well. I dont knwo about these guys here but I talked to them on the phone and for the price I think when I am ready I will go with these guys. They sale a 105 with all the fixins....
http://www.automotivemachine.com/vtwin.htm

Like I said I havent heard anything about them and they are in Texas as well so maybe some locals around there would know more.

Let us know what you decide and for sure what numbers you end up pulling.

That's pretty good, LOL. I don't even let my bro ride my scoot. Next weekend should be a good time.

GMR told me this:

103 and 107 would be the same price. The difference is that the 107 MAY put stress on the crank...and may not. Replacing the crank is 3K extra.

If you're going to spend the 5500 to do the 107 and crank, you might as well pay the 900 extra and go for a 117.

That's all assuming someone here in the Hawaiian stone age knows how to do the labor.