Yamaha Blaster PWK35 Jetting Calculator

Jetting a 35 mm Keihin PWK on a Yamaha Blaster depends on more than the carburetor size. The exhaust pipe, airbox, filter, reeds, porting, temperature and elevation all affect the starting point. Use the Yamaha Blaster PWK35 jetting calculator below to estimate a main jet range, pilot jet range and needle for your setup.

This calculator is for a genuine Keihin PWK35 or PWK35 Air Striker on a Blaster with a 66–68 mm bore and stock 57 mm stroke. It is not intended for a 240 big bore, stroker, Keihin PJ, OKO or generic PWK-style carburetor.

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How to Use the Yamaha Blaster PWK35 Jetting Calculator

Select the parts and conditions that match your machine:

1. Choose your exhaust pipe.
2. Select the airbox and filter arrangement.
3. Select your reeds and level of cylinder porting.
4. Identify the needle and slide currently installed in the carburetor.
5. Select the riding temperature and approximate elevation.

The calculator shows a main jet range and an “install first” main jet at the rich end of that range. It also suggests a pilot range, needle and initial clip position. These are estimated starting settings. Confirm each circuit on your engine under actual riding conditions.

Understanding Your PWK35 Jetting Results

Main Jet

The main jet has its strongest effect at large throttle openings. The calculator adjusts its starting range for your selected setup, temperature and elevation. Begin with the suggested rich-end main jet, then evaluate the engine under load before changing sizes. Do not assume that a jet is correct solely because the engine revs cleanly without a load.

Pilot Jet and Air Screw

The pilot circuit controls idle and initial throttle response. Start with a pilot in the calculator’s suggested range and set the air screw to approximately 1½ turns out. With the engine fully warm, adjust for the best idle and cleanest response. If the air screw has little effect, check the float level, pilot passage, idle adjustment and engine condition before assuming a different main jet will solve the problem.

Needle and Clip

The needle is especially important through part throttle. The calculator suggests CEL below 1,000 feet and DGH at 1,000 feet and above, starting with the middle clip. This is a preliminary choice based on limited Blaster setups; the correct needle and clip must be verified while riding. Selecting the needle already installed lets the calculator flag a difference between your carburetor and its suggested starting needle.

Moving a needle clip down raises the needle and richens much of the part-throttle range. Moving the clip up lowers the needle and leans that range. A clip change cannot always correct a needle with the wrong diameter or taper.

Slide Cutaway

The #6 slide is the calculator’s initial reference for a PWK35. A #5 or unknown slide can change off-idle and low-throttle behavior, so the calculator flags it for inspection. It does not automatically change the slide with elevation. Tune the pilot, air screw and needle first, then investigate the slide if the transition still cannot be corrected.

Check the Engine Before Changing Jets

Jetting changes cannot repair an air leak or fuel-delivery problem. Before tuning, check the intake connections, fuel flow, carburetor passages, air filter and float height. A leak-down test is especially valuable on a two-stroke that has a hanging idle, runs hot or responds unpredictably to carburetor adjustments.

Keihin lists 16 mm as its float-height reference for PWK 35–39 mm carburetors. Verify the measurement procedure and the specific carburetor before making an adjustment.

Read our Yamaha Blaster air leak troubleshooting guide if the engine shows symptoms that do not respond normally to jetting changes.

PWK35 Versus PWK28 on a Yamaha Blaster

A PWK35 is a large carburetor for a standard-bore Blaster. A particular engine, pipe and riding style may benefit from its airflow, but a smaller carburetor can provide a stronger low-speed response on some builds. Carburetor size does not determine the correct jet numbers by itself.

If your machine has a genuine 28 mm Keihin PWK, use our separate Yamaha Blaster PWK28 jetting calculator. Do not transfer PWK28 jet numbers directly to a PWK35.

Yamaha Blaster PWK35 Jetting FAQ

What main jet should I start with on a Yamaha Blaster PWK35?

Enter your exact combination in the calculator and begin with its suggested rich-end main jet. There is no single main jet that fits every PWK35 Blaster. Confirm the setting with the engine warm and under riding load.

What pilot jet should I use?

The calculator supplies a starting pilot range. Choose the final pilot by the engine’s idle, off-idle response and air-screw adjustment, after checking float level and fuel delivery.

Does the PWK35 needle change with elevation?

The calculator suggests CEL below 1,000 feet and DGH at higher elevations. Treat that as a starting comparison, then confirm the needle and clip at part throttle on your own engine.

Should I change the slide when riding at higher elevation?

Not automatically. The slide cutaway affects the low-throttle transition. The calculator uses a #6 slide as its reference and flags other slides for closer evaluation.

Can I use this calculator for a 240 big bore or stroker?

No. It is limited to 66–68 mm bore and 57 mm stroke builds. A big bore or stroker needs its own jetting starting points.

Are the calculated jets final settings?

No. All results are estimates. Fuel, premix, needle, slide, engine condition and weather can affect the result. Start rich and confirm the pilot, needle and main circuits on your machine before riding hard.

For genuine Keihin jets and Yamaha Blaster parts, visit The Blaster Store.

Working on a Yamaha Blaster? Join The Blaster Cult to compare setups, share your build, and get input from other Blaster owners. Join The Blaster Cult