I have an '08 Street Bob. Only performance mods are V&H Straight shots, hi-flow air cleaner, and FuelPak.

I don't have a bunch of money to spend on this and am still undecided whether or not I'm going to tear into my bike or just leave it as is. But I've already bought a few parts because I ran into a deal I couldn't pass up.

I have a 103" kit sitting in my living room, brand new in the box. It is part number 29894-07. Lists for $760 in the HD race parts book. (I got it for much less.) Anyway, it consists of the 3 7/8 flat top pistons and jugs, 255 cams, clutch spring, gaskets, and air cleaner. I don't want to run the 255 cams, and obviously I don't need the a/c. But it was a good deal. The pistons are a stock compression piston when used with stock heads as I understand it.

I don't want anything too radical, just want some more power across the board for everyday riding and to wake it up a bit.

Here's what I'm thinking;
-keep stock cams
-install 103" pistons/jugs
-have the heads decked to raise c/r to about 10:1 or so--no more than10.5:1 (and have the valve seats cleaned up)
-install SE performance valve springs
-change over to 1.725:1 SE rocker arms

The 1.725 rocker arms will give me more lift and longer duration with the stock cams. The reason I'm avoiding cam change is strictly money. I'm trying to avoid spending another $300+ for cams and $400+ or so for a different fuel tuner to accommodate timing changes. I would also like to keep the power curve somewhat where it is, just make more power across the board.

This is my first Harley, and my first engine build of any kind. I'm looking at about $800 in parts plus the head work. That's including the pistons and jugs that I already bought.
How much do I need to deck the heads to get the desired comp ratio (10-10.5:1)? And how much does mild head work like this usually cost? Would it be cheaper to buy the Kompressor heads ($600) which produce a 10.5:1 and come with the upgraded springs? Is there a way to extend the rev limit with out a different fuel tuner?

Am I forgetting anything or am I way off base here? Does this sound like a decent set up?

 

I wouldn't go to wild with compression with stock or 255 cams. It will ping you will need a bigger cam to help bleed off compression. I'd talk with a bilder before you get in too deep and end up with crap

 

Dump the heat-producing, school bus cam on flea-bay.
An Andrews 37 is an inexpensive cam grind that'll carry out much farther than the 255.
Set it at 9.9 cr, and install a 1.900" intake valve, and equalize the chamber cc's, at least, and it'll run good.
More extensive cylinder head mods, such as our Stage II or Stage III's will most certainly show much more.
Scott

 

Can't argue with Scott's knowledge and experience.

But, in view of your comment about $$, would add that the SE204 cams are similar in profile to the Andrews 37 and maybe you could work out a swap for the 255s? IMHO, whether you change cams or not, you need to get rid of the FuelPak. Increasing compression will mean that the timing map will need adjustment; not addressing timing would be a mistake. The TTS Mastertune, TMax with A/T or the new DynoJet Vision are all fairly user friendly and have "self tune" features that will allow you to achieve a decent tune without dyno time. Of course, when the funds are available, a dyno tune would be a good idea.

 

Save your money that you propose to spend on the 1.75 rockers arms. Definitely dump the stock cams and take that saved money and buy HQ 500 cams (inexpensive) or the Andrews 37s as previously suggested. Keep the CR at less than 10.0:1. If working on a budget, install the big bore kit and save some more money by not fussing with the heads, but if using the pistons that come with the kit, you will find that they are most likey down in the hole by about .009, so go with a .018 to a .022 head gasket which will give you a CR increase and at the same time will get the quench to where it needs to be, about .030 or there abouts.

Many very nice budget builds out there right now in todays economy that really do perform well without spending a huge amount of money to wring out the last hp and tq that an engine could produce.

And yes, ditch the Fuelpak and use some of the additional saved funds to buy a tuner such as SEST or TTS.

A 103 build with stock heads, stock CR, the HQ 500s, Supertrapp 2-1 and heavy breather, no other mods just dialed in at 94/104. A few more would be gained by dropping in the thinner head gaskets.

I am becoming a big proponent of "budget builds" as they are the wave of the future in this economy.

 

Thanks guys. I wondered about the stock cams and raising compression. And I didn't realize changing compression will change timing. I've heard good things about the SE258 and S&S 510 cams. Would one of these be a decent choice? There are a couple Andrews cams that sounded good too--50H and 55H.

Its a light bike and I think a mid/high cam would be best. And what about the +/-4* crank sprockets that Andrews has?

 

A Wood 8, will deliver from bottom to top, set up correctly.
Scott

 

Changing compression does not change timing ....

On an EFI bike what controls timing is the Electronic Control Module (ECM) ...

As I understand, a 'user' cannot change the timing on a stock ECM ... a TTS MasterTune, a ThunderMax w/ AutoTune, or a SEPST (or whatever H-D Screamin' Eagle calls the SERT now) have the capability to change the timing curves ... I think the authorized H-D dealerships have the capability to change the timing curve on the stock ECM, but I would be doubtful about the utility (using a 'canned' map without the expertise needed to tailor to a particular bike) ....

When changing out the cams, a change in the air/fuel ratios (AFR) being fed into the EFI system from the ECM is beneficial to maximize the utility of the new cams ... likewise, changing the timing will also allow you to optimize your new setup ....

Just installing the big bore kit will increase static compression from stock 9.2:1 to 9.8:1 ...

There are 'a plethora' of 'bolt-in' cams that would seem to fit the bill for your stated objective ... be careful not to 'over cam' your build and be sure that the lift doesn't exceed the capacity of the stock valve springs (unless you plan on changing them) ...

Also, bear in mind that probably 80% or more of your riding will be between 1,500 and 3,000 RPM ... so, even though you see dyno sheets (graphs) that max out at 100+ HP at 6,000 RPM ... you may never see that in this lifetime (unless perhaps you drag race your bike) ....

Good luck with the build and hope this helps you improve your decision making ....

R/
'Chop

 

You wanne sell those 255's?

 

The cams you mention, except for the 510, IMHO, would be over camming the build, even for the "light" Fatbob. As for the 510s, there are better performers in a 103". Get the right cam and forget about 1.725 rockers and +/-4* advance keys.

I am still focusing on budget. Coolerman wants to buy your 255s, so selll them to him and use that money to buy a set of Andrews 37H or 54H cams; the 54H is a high lift version of the 37H and, IMHO, a better choice for the 103" configuration. No head porting necessary, have a multi angle valve job done, set/equalize chamber volume at 84cc and reinstall with a .030" Cometic MLS head gasket. You will need a set of adustable pushrods. Your exhaust is lacking but will do until you can/want to make the change to a 2:1 system which will boost performance a bit.

Ebay the FuelPak, install TMax w/Autotune, TTS Mastertune or new DynoJet Vision and tune. You are looking at 100/100 numbers and haven't broken the bank. the new tuner is the biggest expense and you can offset some of that cost by selling the FuelPak.