Suzuki RM80 RM85 Phathead cylinder head kit 1991-2025+

Suzuki RM85 Phathead cylinder head kit 1991-2025+

the inserts are cut for the 85 bore which is .5mm larger than the 80.  Compression is nearly identical, slightly less with the 80cc motor.

Chamber selection:

S01 - 6.9cc Stock
S02 - 6.4cc (95+ octane)
S03 - 5.9cc (100+ octane)
S04 - 5.6cc (105+ octane)

 103cc 52/53mm big bore chamber 100+ octane - for use with big bore piston 

Phathead Kits include a head shell with one combustion chamber, two sets of o-rings, cylinder head nuts, copper washers, some stickers for your bike and tool box and installation instructions..

Phathead cylinder heads are made of 6061 T6 billet aluminum.  The material is stronger and transfers heat better than cast aluminum.  The two piece design allows an increase in coolant flow as well as surface area which improves cooling for better consistency and performance.   

The O-ring design eliminates the need to use a gasket.  You can swap chambers without the cost of replacing gaskets. 

One of the main benefits of the product is the replaceable combustion chamber which are available in a range of compression options.

Suggestions : Swap chambers to adjust performance for a variety of riding conditions and track types or keep a spare in case of engine failure.