Screamin Eagle 128 kit

[tbird]

2017 street glide 107 with S&S 475 cam, would like to go s.e. 128 kit. Can you stay with stock heads, springs. Any issues with the thinner cylinder walls? Or should a guy stick with the 124 kit?

[Sunny Jim]

107 - 124. Set it up right(including oil pump upgrade) and you will love it.
Stock heads will work .

[BigT]

Can you buy the Harley 131 cylinders without buying a kit?

[tbird]

Don't want to leave 4 on the table if obtainable with stock heads. bike has 64mm throttle body, Bassani road rage 2 into 1.

[OldMike]

Can you buy the Harley 131 cylinders without buying a kit?

Yes you can, Harley Part #16800210

https://shopbigskyharley.com/products/4-310-big-bore-bolt-on-cylinders-milwaukee-eight-powertrain-black-highlighted-16800210

[Hillside Motorcycle]

With an untouched OE head, you will be leaving a lot on the plate.

[Don D]

Where do you want to be with this 124 or 128? Horsepower and torque and what parts do you already own?

[swingarm]

Hello all,  Tbird did the original post for me while I was waiting to be approved. I have a 2017 road glide with the 107.

This is what I'm wondering.  Can I put the SE 4.310" cylinders and pistons on with my stock heads and springs?  The parts linked below are made for the M8 107" stock 4.37" stroke. I just don't know if the high compression pistons will work with the stock heads? Valve clearance wise.  Obviously I can upgrade the head bolts for the slightly higher compression. I think this combo is 11:1 I would like to stick with stock spring tension, not for cost but reliability. Stock springs work with my S&S 475C cam and I'm a believer in low lifter pressure = longer life.

I have the 64mm Throttle body and manifold https://www.harley-davidson.com/us/en/shop/Screamin-Eagle-High-Flow-64mm-EFI-Throttle-Body-Milwaukee-Eight-Engine/p/27200040

I got the Bassani road rage 2 into 1 long exhaust. https://www.bassanipipes.com/chromeroadrage2into1systemw4megaphonemufflerfor2017.aspx

I got the S&S 475C cam in the bike. https://www.sscycle.com/products/475c-chain-drive-camshaft-kit-for-2017-up-m8-models/

Will these cylinders and pistons work with the stock heads?

4.310" Big bore cylinders. https://www.harley-davidson.com/eu/en/shop/Screamin-Eagle-4310-In-Big-Bore-Bolt-On-Cylinders/p/16800210

4.310 bore X 4.375 stroke pistons https://www.harley-davidson.com/eu/en/shop/Screamin-Eagle-High-Compression-Piston-4310-Bore-x-4375-Stroke/p/21900101

[Don D]

Of course it will work.
What is your goal?

[swingarm]

My goal?......The displacement of the 128 "kit" without having to buy the CNC ported heads and other components I already have. The reliability of the stock spring tension and modest 475 cam lift. I like the near "square" bore and stroke ratio of the stock 107 crank and the 128 pistons. I know it makes for a fast rev and RMP motor. My next upgrade a couple years down the road would be to remove rotating mass. Counterbalancer delete, Baker comp and recluse clutch. Possibly a new crank.

I'm not shooting for any specific numbers as I can NOT find any such tested combinations of my exact components.  I know I'm not gonna get these numbers but WOW! I got the air, the fuel, the bore to stroke ratio, the displacement, the exhaust. Just not the heads or quite the cam in "some regards", but I have faith in the engineering of the 475.

https://www.facebook.com/549378792156024/posts/the-results-are-in-we-have-just-rolled-jays-bike-off-the-dyno-after-the-cam-exha/952248925202340/

If the link don't work:

[swingarm]

Above Dyno would be about 4% less if expressed in SAE vs. STD

[Nastytls]

That is a seriously stout 128".

It also has headwork, a different cam, different exhaust and a modified throttle body by Ward.

[Don D]

About 135 square would be my prediction maybe a bit higher torque number depending on the pipe choice.
The cams timing (short) will be the constraint not the heads yet and the throttle body will be in the way too.

[swingarm]

About 135 square would be my prediction maybe a bit higher torque number depending on the pipe choice.
The cams timing (short) will be the constraint not the heads yet and the throttle body will be in the way too.

Are you referring to the combo I'm contemplating putting together?  Please elaborate. I have a full flow Bassani road rage long cone exhaust.  When you say the cams "short" timing are you referring to the S&S 475 I have?  Is "short" in regards to the IN and EX duration or the lift?  How would my 64 mm throttle body and manifold  be "in the way" I assume you mean constrictive? 
Thanks for the input.

[Don D]

I was referring in general to others, stock motors, as well as your build. The TB you have is fine, no longer in the way.
Yes the cam is short, lift is not the factor I am referring to, the intake duration is 213°@ .050. This is short. The exhaust is used to pull it out with the added biased duration. Me personally, I would not use that cam and be looking for one with a least 10° more duration and an intake close closer to 30° ABDC with compression at 11.3. Under .500 lift, bolt-in with stock springs. Again me personally being as the heads are off to do the big bore I would change the springs to performance springs such as we sell that are 200 spring rate and go in at 80# seat pressure on stock heads. This is a quality thing, stock springs have been known to break when a performance cam is deployed, even in a sensible lift range.

[lonewolf]

Here is one that other than pipe is what you are considering. I, like Don am not impressed with the cam, third one I've seen. [attach=0]

[swingarm]

I was referring in general to others, stock motors, as well as your build. The TB you have is fine, no longer in the way.
Yes the cam is short, lift is not the factor I am referring to, the intake duration is 213°@ .050. This is short. The exhaust is used to pull it out with the added biased duration. Me personally, I would not use that cam and be looking for one with a least 10° more duration and an intake close closer to 30° ABDC with compression at 11.3. Under .500 lift, bolt-in with stock springs. Again me personally being as the heads are off to do the big bore I would change the springs to performance springs such as we sell that are 200 spring rate and go in at 80# seat pressure on stock heads. This is a quality thing, stock springs have been known to break when a performance cam is deployed, even in a sensible lift range.

More like this? ]https://www.compcams.com/mega-8-238-248-hydraulic-roller-camshaft-for-harley-davidson-milwaukee-8-cpg.html[url][/url]

Gross Valve Lift: .472 In/.472 Ex
Valve Lift @ TDC: .163 In/.139 Ex
Tappet Lift @ TDC: .102 In/.087 Ex
Lobe Lift: .295 In/.295 Ex
Duration @ .053: 238 In/248 Ex
Valve Timing Open/Close: 18 In/41 Ex Open & 56 In/13 Ex Close
Int. Centerline: 101.5 In/111.5 Ex
Lobe Sep.: 106.5

[VernDiesel]

No cam guru but that looks better to me. Not sure how to calculate CCP. Harleys pistons (21900101) for a 4.310 x 4.375 show 11-1. Thats with there +1 mm heads. Not sure what it is with stock heads.  Cam & compression combo is key for power heat detonation resistance longevity etc.   

Bigger issue to me is why you want to spend and go through this and then leave half the benefit on the table. Probably only to do much of the work over and spend again. Seems stock heads is breathing through a straw for a 128.  Exchange your heads for on the shelf ported for $800 fully rebuilt with quality workmanship and components or $1,189 for new +1 mm heads. Just my thoughts. Sorry power with longevity costs. Pay it up front or lose one or the other and then pay it in increments as you do over what usually should have just been done the first time.  Best still to check with someone who does it for a living perhaps their is another angle I don't see.

HD Street Performance estimated 135/135 IE 25HP short of the 128 dyno you posted. Why? I'm thinking ported intake heads & cam. Well you are looking to fix your cam idea. As I understand it you still want to match your cam to the actual compression to make it sing. Might want to invest in milling the head different gaskets whatever it takes to get it right the first time. Perhaps it will be close enough and you don't need to go that extra but find out before assembly. 

Last with 128 cubes re-using your existing exhaust will cost you also.  You want one of the pipes with larger and stepped primaries. You may be able to sell your existing pipes to defray that cost. Keep us updated as I'm sure many of us are subscribed. 

[tommy g]

Here is one that other than pipe is what you are considering. I, like Don am not impressed with the cam, third one I've seen. [attach=0,msg1378017]

Looks like a 255  curve except higher numbers.

[Hillside Motorcycle]

Above Dyno would be about 4% less if expressed in SAE vs. STD

2-3 hp at best, not 4% whatsover.
Old sewing circle myth.
Stout engine.