Head. 2 Valve. SIII tuned. HIGH COMP YX150/160 RED TAG SPEC

Head. YX 150/160/170/180 2 Valve Type RED TAG

In stock ready to dispatch

Small hemi high comp combustion chamber

Video info on this cylinder head.

Testing the kit on our static dyno produced up to 20Bhp on the YX150cc & 22Bhp on the YX160cc; up from the stock 16/18Bhp. This includes a good torque gain using the right ignition and carb set up.

Stock valve sizes

Honda port inlet and exhaust

Can be used the Z155 with the right manifold. 

Works with 60mm 63mm 65mm 67mm 2 valve piston kits 

Fitting:

The kit should be fitted by a professional person.

We recommend you don’t rely on the timing marks and set valve timing via LCA, they way it prevents valve damage and will give you the best performance. Reason is some engines have the crank sprocket pressed on not 100% correct.

You need a minimum of 2mm piston to valve clearance 12 degrees before and after TDC on both valves, any less you will have piston to valve contact at higher revs resulting in a valve dropping.

Valve clearances Inlet 3 thou Exhaust 5 thou

Head torque 15 ft-lb’s” Oil nuts and threads”

Cam timing don’t rely on OE marks as they can be wrong, dial cam in 105 degrees LCA both inlet and exhaust.

We recommend you change the cam chain 2 rubber components relevant to the cam chain tension, and only run mineral oil to prevent the rubbers going hard and breaking up.

Valve float caused by the above cam chain tension will result in exhaust valve making contact with piston.

Check piston to valve clearance at 12 Degrees before & after TDC you need a minimum of 2mm

Re check head torque after first heat cycle

Failure to do above can result in valves clipping piston and eventually bending or dropping valves.