Valve Kit 42mm Intake & 40mm Exhaust
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Valve Kit 42mm Intake & 40mm Exhaust

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Code: KIT4240

Price: $347.10

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Description
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Complete cylinder head overhaul kit with unleaded compatible valves and seats. Everything you need to overhaul the cylinder heads on Airhead models with 42mm intake valves and 40mm exhaust valves such as:

R90/6

R90S

R100/7

Also suitable for upsizing models with 38mm exhaust valves such as R75 and R80 when installing R100 Cylinder kit. 


After decades of overhauling BMW motorcycle heads, we found the best combination of products that provided top performance and longest life, fully compatible with unleaded fuels. 

Kit includes: 

Four long life high manganese valve guides

Four top quality OEM valve springs.

Two 42mm Intake Valves

Two 40mm Exhaust Valves

Two 1.709” OD custom unleaded valve seats. 

Additional information: 

Valve guides:

When you install a new valve guide, the internal diameter is often smaller where it is fit inside the head and larger where it sticks out of the head. Original BMW valve guides are pre-sized internally which means they cannot be honed to proper clearance after installation. Our guides are CNC made in the USA to be slightly undersized on the I.D. so they can be honed properly after installation for a true .002" precision clearance which is simply not possible with original BMW guides. Made of the latest high manganese bronze alloy which provides extraordinary wear resistance and best heat dissipation, these guides have consistently shown to have far longer life than original BMW guides. 

Valve Seats:

Our valve seats are USA made to be compatible with all unleaded fuels. It’s hard to count how many of these we’ve installed over the years, but these proven seats have certainly withstood the test of time, with hundreds of them in service all over the country and beyond. They eliminate unleaded fuel valve/seat recession problems that plagued so many BMW motorcycles up through the 1985 model year.  

Valves:

Our European made top quality original equipment style valves are superior to the aftermarket one piece stainless valves for durability and long life. The stem is through-hardened at the tip to prevent wear in the keeper slots and to provide an ideal surface where the rocker strikes the valve, then it is hard-chromed to prevent galling in the guide which extends guide life while allowing close tolerances. The lower part of the exhaust valve consists of the latest unleaded compatible alloy to withstand a long hard life on the exhaust side of the combustion chamber, and the sealing face is Stellite plated for exceptional durability where the valve meets the seat. 

Springs:

We use original equipment valve springs which provide the correct amount of seat pressure for normal use. Higher than standard rate springs are not recommended for typical street/touring use as the higher seat pressures can lead to unnecessary increased stress on valve train components.

This kit is designed to be professionally installed. Cylinder head work requires special equipment and know-how, not recommended for the do-it-yourselfer.

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