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Discussion Starter #1
What do you look for when you do a performance mod? An increase in performance, I know, but how much? What, if anything, do you use to justify the cost of the mod? HP? Torque? Track times? Grin-factor?

Reason I ask: My bike is ~50 hp or maybe a bit LESS in stock form at the rear wheel. Would a 5 hp gain (a 10% increase in performance!!!) really be that noticeable? What about nearly 7 HP? (~13% increase in performance)

How much should one pay for an easily attainable 10-13% increase in HP? Yeah, yeah, it's a cruiser....and who races cruisers, right? :)

Btw, my bike isn't a HD (but a lot of you knew this already)..but this is a question for all. You can do performance mods to virtually any bike.
 

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I break stuff.
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Performance doesn't always mean horsepower. Suspension upgrades will make a bike more 'user-friendly' - feeling more stable at high speeds so you can better utilize the power that the engine makes. And upgrading the brakes will inspire more confidence as well.

Ignition management for a fuel-injected bike usually produces results that are noticed "seat-of-the-pants" ;)
 

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Scooter Degenerate
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Would a 5 hp gain (a 10% increase in performance!!!) really be that noticeable? What about nearly 7 HP? (~13% increase in performance)

Btw, my bike isn't a HD (but a lot of you knew this already)..but this is a question for all. You can do performance mods to virtually any bike.
Big question... without an easy answer.

A 10% gain at the rear wheel should prove noticeable but maybe not as much as your hoping for. Having said that, it depends upon where that new power is delivered in the power band. As an example, i goosed a Mini Cooper S from 163 stock horses to 201 ponies courtesy of a John Cooper Works conversion kit.

The performance difference was barely noticeable off idle but made a HUGE difference in mid range and top end performance. Cost... a neat $10K. Given i was considerably north of 20% in power increase, i would say it was a bargain.

Changing out the exhaust system is usually the most common route to go. In most cases... and without also reworking jetting, or engine mapping, and intake, what you most often end up with is more noise and very little extra go.

Having head work done on a bike like a Harley... porting and polishing.... and adding hotter cams can add a huge kick in the pants but you will also be changing out the ignition at the same time.

As a rule, the higher up the performance ladder you climb on a given motor, the less reliable it becomes.

I've always been amazed at people (myself included) who spend large sums hot rodding a given scoot when it would have simply been easier to buy a different bike. There are guys who are running 100+ hp Sportsters (not Buells) To kick that motor up to 100 ponies and still have it reliable is a considerable investment in time and money. Unless you are a serious wrench you could probably buy another Sporty for what you're going to pay for accomplishing that goal.

I have probably helped you not at all... sorry about that. I also agree that suspension upgrades can represent some of the most significant and cost effective performance enhancements that you can make.
 

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Discussion Starter #4
Thanks for the responses!

Yes, suspension can be a great performance mod, but I was meaning to include only specific lower cost, easy to do engine mods: exhaust, air, fuel.

However, I think my next upgrades actually will be suspension. :)
 
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