Category:Performance Tuning

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Revision as of 21:31, 18 December 2006 by Dan (talk | contribs) (→‎Piston Kits)
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Better, Faster, Stronger

You'll get noticeable power improvement on most mopeds by the following mods:

Bigger Carburetor

Installing a bigger carburetor will increase the amount of fuel leading to more power. The hard part is getting the air to gas ratio correct so that you don't cause a seizure or foul plugs. Controlling the gas flow can be done by changing the size of the jet. Controlling the air flow can be through the use of special air filters or by drilling holes in your air box.

High-Compression Head

Cylinder heads can be obtained that increase the compression in the combustion chamber leading to faster strokes leading to increased speeds.

Performance Crank

Supposedly installing a performance crank increases your speed, but I never understood how. Everybody I've talked to that knows about them says that they do indeed increase your speed.

Performance Exhaust

For most mopeds, this will be the best performance improvement, and the easiest for the average person to do in an afternoon.

Many mopeds of 1970-1985 vintage had exhausts tuned to deliver the most power at approx 25mph. As the engine goes faster, it's cycle rate moves out of the power band of the exhaust, and the exhaust begins to restrict the amount of fuel available for combustion, which self-limits the top speed.

However, if you replace the stock muffler with one with a power band that is higher, your top-end speed will increase, but at a cost of the low end power. For most moped riders under 200lbs, this really isn't an issue.

For example, on a Honda Hobbit, you can get up to an 8mph improvement, just by swapping out the stock muffler with a Proma Circuit exhaust.

Of course, every model of bike is different, and you'll need to use the forum search function on the 'Performance Tuning' forum to find what people recommend for your model.

Piston Kits

These kits replace your cylinder and piston with a larger bore. Generally, you will also need to re-jet your carburetor to allow a greater volume of fuel/air mix to enter your engine.

They can be done in weekend, and generally give good performance.

However, most kits recommend a 300 to 800 mile break-in period after installation, to allow the rings on the piston to use the fine scratches (call the honing) in the cylinder to gently polish into a smooth, well seated finish.

Overrevving the engine, and showing off your new kit to your friends by throttling all the way up is a sure way to destroy your new kit if it's not properly broken in.

Note that some kits can increase your engine combustion area above 50CC, which may change your moped to a motorcycle due to your state's laws. Make sure to check with your DMV before you spend the money on a kit!

Cylinder Porting

Cylinder porting is one of two arts - the white art of Port Matching, and the black art of Port Reshaping.

See Smitty's full article, as transcribed from the forums, for a guide to cylinder porting from the guy who does it for a living.

Gearing

By changing the front and/or rear sprocket you can redistribute speed to top or low end depending on your needs. Usually increasing top end with this method decreases low end, and vice versa.

Real Fast, But Not For Long

Nitrous Injection

Makes you go real fast for up to 5 seconds.

The problem? You run really lean for those five seconds, and every time you use the nitrous, you have a good chance of causing your engine sieze from lack of lubrication.

JATO Rocket

A Jet Assisted Take Off unit will make you go really really really fast for up to 7 seconds...

... straight into a tree. And fry everybody behind you.

Subcategories

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Pages in category "Performance Tuning"

The following 103 pages are in this category, out of 103 total.