I have a 2008 Road King Classic with 42,000 miles (bought new in April 2008, I am only owner and rider). I am considering an engine upgrade and would like to hear opinions on whether to go with the S & S 106ci kit with EZ start cams (either 551 or or 583) or the Harley Davidson 103 upgrade with SE 255 cams.

My bike is a 96ci Road King Classic with Rinehart true duals, a stage 1 ac, and a power commander III, lowered at the rear with the HD lowering kit.

I have been reading extensively on this forum and others, so I know that are other combinations and cams, but I am inclined to limit myself to these two choices. I have about $2000 to spend, plus or minus a few hundred, and I will pay a pro to do the install, because it is more than I want to handle. I have estimates for complete install (parts and labor) for the 106 kit for $2300 (including power commander custom map), and for the HD 103 kit for 2000 (not including power commander map or dyno tuning - which I will have to get elsewhere -and with manual compression releases and required machining of stock heads included -- not needed for the 106 if I use the S & S EZ start cam)

I am looking for improved low to midrange acceleration and power-- for example, I want the bike to jump when I twist the throttle in 6th gear when going 70 to 75 mph, so I can accelerate quickly another 10 mph or so. I generally ride 1 up with a light load. I also want improved pick up (torque) off the start. I usually in ride (in all weather -- mid Atlantic east coast summer and winter) on the highway at highway speeds above 60 mph, at sea level, in non-mountainous terrain, though I want hill climbing power if possible).

I want to use stock heads, at this point, and limit use of any other parts not included in these kits, if possible (need for recommended extra parts would be relevant in deciding which kit to go with).

My sense from reading is that both of these kits are good, and will be a big upgrade in power, so the basic question is this: Does the 106 ci kit provide enough additional torque and hp (and reliability) where I ride to be worth the extra money? To put it another way, is it better, or about the same?

Secondary questions:

Any hidden disasters in either?

What should I expect with gas mileage?

And finally:

Any thoughts on the cam choice: S & S EZ start 551 or 583? HD 255 or 253 or 254E?

Thanks for any assistance.

 

Don't know much about the S&S EZ Start cams but can tell you that the 255 peaks early, requires 200psi ccr to really make power and falls on its face early. I know you have limited yourself to two choices but the H-D 103 build with the new Andrews 48 cams makes real nice broad and flat torque curves which sounds like what you want. If you are stuck on SE cams, the 259E would probably better suit your riding style than the SE255. The later intake close on the 259E and a .030" head gasket will put your static CR at about 10:1 and cranking compression in the low 180s; no compression releases required.

IMHO, there is not a cam that will make the bike "jump" when you hit the throttle in 6th gear; downshifting is easier on the engine.

You might find that you would be happy with just a cam change. The 48 cams and thinner head gasket should make 100+TQ/100+HP with a good tune. Not sure how the RH TDs will play in compared to a 2:1 system like the Fatcat; the TDs may hold the torque back a bit??

The later heads flow pretty well but a little bowl work, good multi angle valve job, trimming guides and decking for just a tad more compression with the 48 cams and a good tune will fit your budget and be a strong performer. I know that's not part of your plan, but JMHO.

 

Appreciate the thoughtful response. Will take a close look at your advice on cams.

 

There are a series of videos on youtube... goggle S&S bikers choice youtube introduction and you will find video's on each stage of a four stage build. The video's show each step of the build in detail and also the dyno results of each stage. With the 106 kit and 585 cams, the 2010 roadglide made about 100 hp and 107 torque. Adding the S&S reworked heads the engine made 106 hp and 108 torque.
Check out the video's... they go into extreme detail on how to do the build.

 

We bore your existing cylinders to 3.934". using our proprietary Wiseco/Cometic piston/gasket set. Over 4 years of doing this now, and over 25 years boring Harley cylinders.
Combine that with one of several cams, and you'll be flipped!!!!
Head work will only amplify the delivery, and overall output even more.
Scott

 

rumor has it the S&S 106" cylinders are being made oversea`s,we wont use them.we also prefer to bore the HD cylinders using wiseco or CP piston kits(we use wiseco)

 

Why do you guys prefer to bore hd jugs?
Is it a business reason. More profit behind it? Or a technical reason? I totally understand the profit reason if that's the reason. I'm torn between going the s & s route myself.

 

I just recently did my 08 SG up to the 103. Bored stock cyclinders. Cleaned up the heads a bit. Put in Woods cams. Already had race tuner, Rineharts & SEAC. Made 103 hp & 117 torque and I'm really impressed. Bike really runs great, especially from a dead stop. WOW! Total was about $1800 @ Clinton HD. Good luck choosing....Ride safe...

 

Djl, Don't mean to contradict you as you obviously know more about Harley mechanics than I do, but I can't say that I've ever seen anybody break the hundred HP mark with just a cam change and thinner gasket. You have?

To the OP, I know yousaid you are only considering the HD and the S&S kits, but you could get everything you're looking for in a 107" kit from Jamie at www.fuelmotousa.com, including a full dyno tune afterwards for right under 2K. I'll be doing this shortly myself. I've heard nothing but rave reviews from people that have went that route. Good luck with whatever decision you make.

 

One more suggestion.
Go with your 106"er.
Set the cr @ 10.25, and install a Wood TW-6-6.
Install a set of heads that'll push off 160 plus cfm @ 10".
The bike will pull like a tractor throughout the rpm band, and will be particularly strong where you want it.
120 ft/lbs of torque should be within easy reach, tuned correctly, as we have seen this here almost a decade ago.
Scott