This summer I bought my first motorcycle - a 2014 Harley Davidson Forty-Eight XL1200X. Since I had no previous experience with motorcycles but still wanted a Harley, the Sportster seemed like an obvious choice. Also - as in Europe Harleys are quite a bit more expensive than in US and I didn't want a used bike - it was a matter of what I could afford. Having ridden the bike almost every day since I bought it, I must say I really like the relatively light weight and quick manoeuvrability (compared to bigger Harleys). There are a few areas in which I would like to improve the bike, however. One of which is the engine.

I looked through the online Harley Davidson catalog and realised that if I want to use only what Harley calls "street legal" parts, the gained performance increase would be very minimal. So naturally a question the arises as to why are some seemingly innocent parts considered as "race only".

The parts in question are:
- Screamin' Eagle Pro CNC Ported Factory Cylinder Heads;
- Screamin' Eagle Pro Perfect Fit Pushrods
- Screamin' Eagle Pro Sportster High Output Cam Kit
- Screamin’ Eagle Pro XL1200 Forged High-Compression Piston Kit

What is hard for me to understand is - how a cylinder head with slightly larger ports, cams to match and slightly increased compression would render the bike illegal for street use?
Is it only as a warning that as soon as you want to modify the engine you're on your own and warranty won't cover any damage or is there a real danger of not conforming to some regulations?

What I certainly don't want to wind up with is an actual race engine with service intervals measured in hours and/or races, e.g. change engine oil every 15 hours, check valve clearance every 30 hours, use race fuel only etc.

So I guess to concisely formulate my questions:
1. Other than voiding the warranty on my motorcycle - do the race only Screamin' Eagle parts indeed render my motorcycle illegal for street use (I would use the Screamin' Eagle Street Cannon Slip-On exhaust and a Heavy Breather Air Cleaner which would mean that intake air is properly filtered and exhaust conforms to noise and emission standards)?

2. What kind of performance gain should I expect (of course, the electronics will be recalibrated as well)?

3. Does the fuel matter (in Europe the 95 is standard and 98 is freely available in almost all gas stations)?

4. Will it significantly decrease the life of the engine?

I would really appreciate the help and advice of someone who, perhaps, has made similar modifications or has experience with sportster engines.

 

Hi Mr P from not very far away and welcome to HDF.

Bear in mind that things like 'race only' are aimed at the home US market. Here in the UK we suffer from never receiving UK-specific English 'translations', unlike other countries that use different languages! Your owners manual probably tells you to ride on the right, despite the utter folly of doing so. It was not so long ago they also told us to use the rear brake only for routine braking - get the picture?!

To answer your queries:

1. They render the bike illegal in that it no longer meets EPA (or any other for that matter!) regulations on noise and exhaust emissions. However it is routine amongst many car and bike owners to ignore them! Be wary of loud exhausts here in the UK, as MoT stations are getting picky.

2. Up to twice the HP of a stock unmodified bike.

3. In general our European fuel is better than in the US, we don't have to be so careful. The US uses a different scale of octane numbering system for their fuel to us, so they are not comparable. US 95 is not the same as EU 95.

4. Not to a level that most of us will be bothered by!

The stock induction system as well as exhaust are very quiet, so what you will find is when installing any aftermarket air filter or silencers is that the noise levels will be significantly increased, even if they are the only changes. The cams will further increase noise levels (and performance!).

Hope that helps a little.

 

Hey Mr. P

I've just bought a 2015 Forty Eight and have put the Heavy Breather & Street Cannons on it so can speak from experience.

The noise increase is surprisingly minimal. It has the nice harley tone but isn't 'loud' - Here in Sydney, the police are quite tight on EPA noise tests and I have (touch wood) ridden past plenty in the past few months without so much as a head turn. If you wrap your headers black as well, the mods are quite stealth for what of a better word.

As for power, I never rode it before the mods so couldn't tell you the difference - It goes some when you give it the bean and can be chilled around the city, so works fine for me.
One thing is that it spits a bit in first when you start from cold, but I've put this down to it needing to be mapped properly.

Hope that helps you with your decisions.

 

95 should be fine, as 93 is usually what is readily available here in the states.

Your engine reliability will be about the same. Any well built engine will last a very long time, and depending on the parts you used it should long outlast the rest of the bike.

Street legality is a joke. No one cares. No one is going to pull you over and ask what you've got going on with the engine. Bikes never need an inspection to determine emissions so that is null and void as well. If you want to go fast, do it, and don't worry about the legality nonsense.

As far as screamin eagle parts go, don't do it. They're junk. For the money you are going to spend getting all those parts with the fancy eagle stamped on them, there are other brands that will do even better for less money. Hammer performance and NHRS are two perfect examples. I think here on this forum there is a thread where people post up their dyno numbers on their bikes. One guy put ALL screamin eagle parts in his bike and he was a good 20hp short of everyone else who used comparable parts from legit performance builders. It's ulitmitely your money, but you typically want to get more bang for your buck.

My bike is running all Hammer performance parts, and I'm pulling around 95hp. The bike flys. It beats most crotch rockets any day, and still cuises at about 40-45mpg.

Good luck to you though. Shopping for upgrades is exciting! And highly rewarding when you build it yourself

Kev

 

SE is not an answer, it is a question. The answer is NO.

 

Thanks for all the responses!

As I am new to bike modifications (and bikes in general), I looked at Screamin' Eagle because they are offered in the Harley catalog.

I suppose I should do some research on parts by other manufacturers as well.

 

Where are you located old chap? There may be someone close by who can help.

Bear in mind that you are on a US website, which cannot answer all the questions a Jonny foreigner bumps into. For example 'street legal' means it complies with US EPA emissions regulations, which don't apply over here.