One idea at a time in focus mode
Sourced notes on original reeds, Boyesen and carbon petals, and the manifolds sold with 34 mm blocks.
Before you start
Your own risk. Wrong jetting or timing can seize the engine. This is information, not advice.
How many steps: 3
Step 1 of 3
The stock reeds are already a fibre composite.
Hartrusion says the standard petals are a fibre composite, and that their behaviour changes after years of use, so a new set can feel better than a tired original set. He also says the sealing face of the cage is only milled, and that flattening it on 400 to 600 grit paper is a free job whose measurable effect he doubts. Reed-tip clearance is not in the Haynes extract used here. The mounting bolts are 7 Nm. The gap is To verify.
Step 2 of 3
A 34 mm manifold is a separate part from the reeds.
Boyesen petals for the original cage are the dual-stage type: a short upper petal and a larger one under it. That is Hartrusion’s description. He does not publish a power figure. Moto Tassinari VForce 3, as he describes it, is a split block with carbon petals. Fitting it means cutting the intake manifold, and the kit he looked at did not include a spigot. Italkit Double Prism, on the same page, is also split and is supplied with a manifold for a 34 mm carb. A separate Italkit W-Force listing supplies an eight-petal block and a 34 mm manifold, states that the original manifold is 28 mm, and says the carb connection is 40 mm, which that listing matches to a Keihin PWK 32–36 mm or a Mikuni TM(X) 32–35 mm. Polini Superval is an older multi-petal block. Hartrusion quotes the kit note that the idle jet should drop by about 20 percent and the main grow by 20 to 25 percent, and he does not judge whether the shape is actually better. Those percentages are the kit note, not a setup checked here, and they are not a starting point for standard petals.
Step 3 of 3
Cheap carbon reeds can break and wreck the engine.
Licence, MOT, insurance or a seizure.
Hartrusion’s warning is specific: carbon petals from a reputable maker are widely used, and cheap carbon sheet cut into petals is not the same part. If a petal breaks or sheds fibres, the debris can damage a main bearing, the connecting rod or the bore.
This guide is done. Your place stays on this device.
Hartrusion says the standard petals are a fibre composite, and that their behaviour changes after years of use, so a new set can feel better than a tired original set. He also says the sealing face of the cage is only milled, and that flattening it on 400 to 600 grit paper is a free job whose measurable effect he doubts.
Reed-tip clearance is not in the Haynes extract used here. The mounting bolts are 7 Nm. The gap is To verify.
Source: Hartrusion, tuning: reed valves
Boyesen petals for the original cage are the dual-stage type: a short upper petal and a larger one under it. That is Hartrusion’s description. He does not publish a power figure.
Moto Tassinari VForce 3, as he describes it, is a split block with carbon petals. Fitting it means cutting the intake manifold, and the kit he looked at did not include a spigot.
Italkit Double Prism, on the same page, is also split and is supplied with a manifold for a 34 mm carb. A separate Italkit W-Force listing supplies an eight-petal block and a 34 mm manifold, states that the original manifold is 28 mm, and says the carb connection is 40 mm, which that listing matches to a Keihin PWK 32–36 mm or a Mikuni TM(X) 32–35 mm.
Polini Superval is an older multi-petal block. Hartrusion quotes the kit note that the idle jet should drop by about 20 percent and the main grow by 20 to 25 percent, and he does not judge whether the shape is actually better. Those percentages are the kit note, not a setup checked here, and they are not a starting point for standard petals.
Source: Hartrusion reed-valve page, and an Italkit W-Force listing
Hartrusion’s warning is specific: carbon petals from a reputable maker are widely used, and cheap carbon sheet cut into petals is not the same part. If a petal breaks or sheds fibres, the debris can damage a main bearing, the connecting rod or the bore.
Legal and safety. A broken petal in the crankcase is an engine failure, not a tuning result. If you are unsure which petals you have, do not run the bike until someone who builds these engines has looked.
Source: Hartrusion, tuning: reed valves
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