UMA BYPASS (GRENADE) 90 YAMAHA with BREATHER TUBE

The UMA Racing Bypass (Grenade Design) is a functional engine accessory designed to regulate internal crankcase pressure. While many riders choose it for its distinct “Grenade” aesthetic and vibrant anodized colors, its primary purpose is to help high-performance or modified engines breathe more efficiently.

It is typically installed by replacing the stock oil filler cap or a specific crankcase plug, connecting it to a breather hose to vent excess pressure.

Key Features

• Pressure Relief: Its main job is to relieve “blow-by” pressure in the crankcase. By allowing this pressure to escape, it reduces the workload on engine seals and helps prevent oil leaks.

• CNC Aluminum Construction: Machined from high-quality alloy using CNC technology, making it durable and resistant to the high heat of the engine bay.

• “Grenade” Design: Features a unique, ribbed outer shell that resembles a small grenade. This textured design isn’t just for looks—it also provides extra surface area to help dissipate a small amount of heat.

• Dual Angle Options: Usually available in 45° or 90° tube angles, allowing you to route the breather hose cleanly regardless of your bike’s frame layout.

Why Install a Bypass Valve?

1. Modified Engines: If you have a big-bore kit or high-compression piston, your engine generates more internal pressure than the stock breather system can handle. This bypass provides an “emergency exit” for that air.

2. Engine Longevity: By controlling internal pressure, the engine can rotate more freely, which slightly reduces internal friction and helps the engine run cooler.

3. Visual Customization: It is one of the most popular “engine dress-up” parts because it replaces a boring plastic oil cap with a high-end racing component.

Installation Pro-Tip

To get the best performance, pair the Grenade Bypass with a UMA Racing Venthose (Breather Hose). These hoses are made of reinforced, heat-resistant material that won’t collapse under vacuum or melt when touching the engine block.

Note: Ensure the hose is routed away from your rear tire. Since the bypass vents engine vapors, a small amount of oil mist can sometimes escape; you don’t want that mist getting on your tire’s contact patch.

FAQs

What does a bypass do?
It helps vent crankcase pressure and blow-by gases from the engine.

Will this increase horsepower?
Not directly, but it can improve engine efficiency and responsiveness on modified setups.

Is it universal fit?
Yes, commonly used on many motorcycles with custom hose installation.