Editorial - Modifying Your ATV

Suspension before Engine

Today's factory ATVs are fast and agile right off the dealer floor. Most sport quads, and even some utility models, have enough speed and power to satisfy the average rider for quite a few riding seasons. However, throttle response can lag on new units because of restrictive exhaust systems, so many riders still find themselves reaching for an aftermarket exhaust and making air filter mods to boost bottom end power.

For some, these mods aren't enough. Many more quad owners still find themselves itching to unbolt their cylinder head, open up those ports and drop in cams and a piston. This is the point where some riders need to step back and ask themselves if those internal engines mods are a necessity. Unless you're competing in the pro or pro-am ranks, they aren't necessary.

Many new quad owners look to open up their top end and drop in engine performance parts as one of their first modifications before adjusting or upgrading their suspension.

I fully support the idea of bolting on an exhaust system, removing the airbox lid and re-jetting or adjusting the fuel map to improve throttle response and give a quad's bottom end a boost. My first quad, a Suzuki LT185, got a Cobra DG full exhaust before anything else. Such mods don't reduce the dependability of today's stock four-stroke engines, unless you don't know what the phrase air filter maintenance means, and these mods in most situations don't create an engine with more power than the rider knows how to handle safely.

Opening up the top end is a different story. Even if an expert engine builder handles your internals, the work immediately reduces the engine's lifespan. Aftermarket cams and pistons are designed for performance, not lifespan. And that increased performance can put a greater strain on internal parts your less likely to upgrade, such as the cam chain, valves and valve springs, timing guides, cranks and gears. These parts can fail under the added torque, heat and strain of an improperly over-juiced engine. 

Often, new quad riders don't take the time to get comfortable with, and find the limits of, their stock suspension.

The factory shocks on today's modern sport quads are very high-tech compared to models from 1980s and 1990s. Rebound, pre-load, and high and low speed compression adjustments come stock on today's high-performance ATV models. Suspension tuning can be tricky at times, but trial and error and a good notebook are much more manageable than cracking open the top end numerous times after improper tuning leads to a failure. And learning the fine art of tuning shocks is an invaluable asset that can improve any quad's handling.

Suspension mods, like the Fox/ATV Four Play front end on the TPR project YFZ450R, will do more to change the feel and performance of your quad's ride than some internal engine work.

And, if you find your shocks bottom frequently and can't handle the obstacles you're throwing at it, then upgrade them! You may not be tapping into the full potential of your stock engine if the suspension is holding your quad back. A new set of quality, tuned shocks can lower lap times and lengthen a day on the trails.

The logic is simple: It's harder for the engines in today's sport quads to out-perform their suspension and create a dangerous situation. But a 480cc big-bore kit in a stock-suspended Yamaha YFZ450 can put a novice rider in a sketchy situation, whether the situation is shooting hills in the dunes, skying on a motocross track or climbing gnarly, tree-root lined hills in the woods.

Following this idium, suspension before engine, allows you to safely find the limits of your quad's chassis. Once you do that, then you can decide if the suspension you're running can handle the kind of speeds you're capable of riding at.