Replacing the Fuel Line on a 1987 Yamaha PW50

Shop parts for a 1987 Yamaha PW50 Dirt Bike.

Rubber fuel hose is among the cheapest parts on a 1987 Yamaha PW50 and one of the few that can end a ride outright. It hardens, cracks, and weeps fuel where you cannot see it, eventually either starving the engine or putting gasoline somewhere it should never be. Swapping it needs no specialty tools and no shop time.

Red Flags During a Pre-Ride Look

Catching a bad line early is mostly about paying attention during routine checks. On a 1987 Yamaha PW50, these signals should send you looking at the hose.

  • Wet spots on the frame or cases. Fuel evaporates fast, so look for residue rather than liquid.
  • Fuel odor that will not clear. A leak too small to see is still large enough to smell.
  • Hairline splits near the clamps. The clamped section takes the most stress and cracks first.
  • Hose that holds its bend. If the line refuses to straighten, the rubber has hardened.
  • Symptoms resembling a fueling fault. Bogging on hills or running lean with a full tank.

What Actually Kills a Fuel Line

Two things degrade a fuel line: time, and what sits inside it. Rubber loses flexibility as it ages, and a hose that spent eight years on a 1987 Yamaha PW50 has been hardening the whole time, ridden or parked. Hardened rubber cannot absorb vibration, so it cracks where it stretches over a fitting. Ethanol-blended gasoline is the other half — fuel sitting unused for months attracts moisture and breaks down, which is rough on hose material and leaves varnish behind. Add a dry climate baking out what flexibility remains, and a line that looked fine last season can be brittle by spring.

Confirming the Fuel System on Your 1987 Yamaha PW50

Fuel delivery on the 1987 Yamaha PW50 is carbureted, so the plumbing is about as simple as it gets on a two-stroke dirt bike — tank, petcock, hose, carburetor. That petcock is the most useful thing about this job. Turn it off and the fuel stops, which means no siphoning and no fighting gravity while you work.

Parts, Tools, and a Safe Workspace

This is a low-cost job, and most of the preparation is about containing fuel rather than turning wrenches.

  • Replacement fuel line in the correct inside diameter and length for your 1987 Yamaha PW50. Match the original rather than guessing — oversized line will not seal on the barb.
  • New clamps. Spring clamps lose tension with age, and a small clamp kit costs very little.
  • Nitrile or rubber gloves. Gasoline absorbs through skin.
  • A fuel-safe drain container and a funnel if you plan to reuse the fuel.
  • Pliers and a small flat screwdriver for spring and screw clamps respectively.
  • Shop rags and eye protection.

Take the fuel handling seriously. Vapor sinks and spreads, so ventilation matters more than most people assume — work outside or with the door up, and kill any appliance with a standing pilot flame. Keep the drain container closed between pours and wait for the engine to cool.

Getting the Old Line Out of the Way

Petcock off, first thing. That valve is why a carbureted bike like the PW50 is forgiving here: shut it and the fuel stops moving.

Capture the fuel sitting downstream. Fit a clear hose to the float bowl drain nipple, run it to your container, and open the drain screw a couple of turns. The bowl empties in under a minute. Close the screw afterward, because a bowl that will not hold fuel is frustrating to diagnose later.

Clamps come next. Squeeze the ears of a spring clamp with pliers and slide it clear, or back off a screw clamp until it moves freely. Then persuade the hose off the barb with a twisting motion rather than a hard yank — old rubber bonds to metal, and a straight pull can bend a carburetor inlet or petcock spigot. When the line is truly seized, slice it lengthwise and peel it away.

Routing and Securing the New Line

Use the removed hose as your measuring stick and cut the new one to match. On a 1987 Yamaha PW50 the correct length stays clear of moving and hot components while still absorbing engine movement without pulling on either fitting. Square off both ends with a sharp blade.

Start at the petcock. Work the hose on until the barb is fully buried — a partial seat is the most common cause of a post-repair leak. Warming a stiff hose helps it slide; lubricating the fitting does not. Leave grease and oil out entirely, since either prevents the rubber gripping properly and can end up inside the carburetor.

Then connect the carburetor side and dry-fit before clamping. Mount the tank if it was removed and verify the hose is not trapped, stretched, or resting on the head. Once the routing looks right, place a clamp at each end over the fitting itself and bring it to snug. New spring clamps are hard to overdo; screw clamps need restraint.

Final Checks and the First Start

With the new line in place, open the petcock and stop. Let the 1987 Yamaha PW50 sit five minutes over a clean surface and use that time to examine both joints under a flashlight. A properly seated hose stays completely dry; anything else needs attention before the wheels turn.

The running test comes second. Fire the engine, let it warm, and look again — expansion and vibration find seals that hold fine cold and still. When you find a weep, resist the urge to overtighten. Disconnect, verify the hose is pushed fully over the barb, and reassemble; that is nearly always the actual problem.

Wrap up by disposing of the drained fuel appropriately and taking another look at the connections after your next ride. On carbureted bikes an inline filter, if fitted, is a serviceable part worth replacing at the same time. For deeper background on keeping fuel lines healthy between seasons, our complete overview of dirt bike fuel line service is a useful companion read.

Related Shopping Categories

Shop Fuel Lines for a 1987 Yamaha PW50 Dirt Bike.

Shop Fuel Line Clamps for a 1987 Yamaha PW50 Dirt Bike.

Shop Petcocks for a 1987 Yamaha PW50 Dirt Bike.

Shop Fuel Filters for a 1987 Yamaha PW50 Dirt Bike.

Shop Fuel Stabilizer for a 1987 Yamaha PW50 Dirt Bike.

Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your dirt bike's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.