Intake port sleeves (2) for converting 32mm 850 RH4 heads to 30mm RH10 ports for improved perfomance. Also works for Combat heads.


850 street bike 30mm RH10 heads are prefered because the 30mm ports have a higher flow velocity.  Easily convert your 32mm ports to 30mm by simply sliding and gluing in these aluminum sleeves with loctite – you don’t even have to take off the head (just the manifolds).  The end of the sleeve is flaired so flow is not interupted.  Re-use your original manifolds.  Expect an immediate improvement in throttle response (see installed sleeve in stock RH4 head).