Hi folks,

Just checking thoughts on viability here. Specs currently are 2014 Dyna Street Bob. I have Fueling 574 Cams, and Vee Twin racing ported heads (specs attached), Supermeg exhaust, DK AC, and a SE 50mm Throttle Boddy with 4.9 injectors. Bike runs beautifully but as always....

I'm wondering about picking up a Fuel Moto 110 Drop in Kit (Specs below). I understand that typically most people would build with an end in mind vs. piecemeal but I just can't seem to ever do that.

So, if I bought this kit with the included pistons, any thoughts as to if everything would mesh well? What do you think I should do for compression on the pistons? I run heavily in the 3000-4500 RPM range. I have fun regularly but am not silly or anything with my riding. For those that know me, I just like a project sometimes...

Any thoughts would be greatly appreciated.

The Fuel Moto Extreme Duty cylinders with hi-strength steel liners allow "Drop in" installation of 110" cylinders (4.000" bore diameter) without boring cases on 2007-2017 H-D Twin Cam engines with 4.375" stroke. Also included is CP/Carrillo complete piston kit with your choice of 10.25 - 11.0:1 compression (custom dome machining available), Cometic MLS .030" head gaskets, and OE H-D base o-rings

 

The 10.25 pistons with your heads would put you at the limit of using those cams. Consider changing cams to take advantage of the added compression which will be available to you. I hear the Tman 590 is quite nice..

The rest of it will probably transfer over. Why not go with HD 110 kit? What's your crank run-out?

 

Thanks Matt,

Jeez this will put me at the 3rd cam change, yay! Out of curiosity, what exactly changes that puts me at the limit?

I hadn't really looked at the HD kit, mostly because I hear such great stuff about the FM products. I'll take a look at the pricing on HD. I haven't looked at runout yet, guess I need to buy the tool.

 

You might be okay keeping the cams. I'm just assuming with 10.25 pistons and 81cc heads you'd be around 9.6:1 corrected with the 574. I don't know much about them, maybe they do well there.

 

I assume the head gasket is .030"; correct me if wrong and disregard what follows except the "talk to Kirby" part.

103" displacement, .030" head gasket, 81cc heads and the 574 cams puts you pretty much in the sweet spot for those cams. If you were to drop in the 110 kit you would have to open up the chambers a bit to retain the .030" head gasket or go with a stock head gasket, otherwise, corrected jumps to near 10:1 and ccp to near 210; may work for some but OTT for me.

Kirby did the heads so why not give him a call and talk about a 107" configuration that would just involve a bore/hone job and new pistons. Keep the 574 cams, or not depending on what your goal is (you haven't said nor have you posted any dyno numbers from the current build) and talk to Kirby about a replacement Kirby can guide you better than most of the forum members; he know what works with his heads. Cheaper option and a strong 107" motor will surprise.

 

Yeah I will definitely reach out to Kirby. You know me though, since I ride mostly year round I prefer to just buy the parts drop them in and then sell the originals for pennies on the dollar. If I send my cylinders for boring I'll wait until the summer when it's stupid hot here.

The current build came in at 105hp and 100tq, a bit of a disappointment emotionally but it rides beautifully

Goals I guess would be 115 squared or so but mostly having fun in the mid range.

 

I would be disappointed with those numbers from a 103" as well. You have a decent combination; tune could be lacking or the cam and pipe may not being playing well together. I am betting Kirby can put you on 115 numbers with a 107 but he might suggest a cam and/or a pipe change.

 

Perhaps so. Maybe it is the combo, lots of folks with the same pipe which should support much stronger performance but with different cams, and others with the same cams but different pipes with better numbers. Pretty strange!

 

Well, I'm gonna be the honest one and tell you what you need to hear, quit this nonsense talk about drop-in smop-in, cut to the quick, you need to tear it all down and do a 117", you know the deal by now, dismantle, send off the bottom end, all that jazz, no talk of this being your 3rd cam change, this would be your "last" cam change 'cause you know a good 117" is what you want and need!
Bam, 135hp/tq at your finger tips, do it, there's your project staring you in your face, don't ignore the need, give in to this vice, it's a calling to you

But by all means, do something and make a good thread on it

 

^Sounds like good advice to me.