XS650 Cylinder Head Washers / Torque Specs.

Ques:

  I am rebuilding the head on my 80 G model. I saw in Mikes XS catalog that four of the rubber washers are required for rebuilding the head, mine had all 8 studs with washers on them. Did someone pull a fast one when working on this or are there really supposed to be 8 metal washers? CC.

Ans.

  Stock the XS motor has 4 combination rubber and steel washers on the four outside end studs, and 4 solid steel washers on the inside 4 studs. On rebuilds I put one thick copper washer from a GS1100 Suzuki head on each of those 4 studs. MikesXS does sell them if you want to replace them as an original OEM, I think they are about $2.50 each. They usually shred when you remove or retorque them. All the stock XS heads I have removed are always loose on the outside ends because of those 4 dumb rubber/steel washers. That's why most of the stock XS motors usually seep oil or blow the head gasket on the fin area on the 2 outside end cylinders. The 4 ends of the 8 head studs are always loose compared to the inside 4 studs. Not good.

  I would go ahead and leave the metal washers you found under the studs since they were not seeping oil anyway and were thick enough to not have the threaded end of the stud go through the top of the dome nut. GS1150 and GSXR race and stock Suzuki's have all twelve 10mm head studs with copper washers fitted as OEM. All the KZ900 and KZ1000 Kaws have the end four outside studs with a thin copper washer under the dome nuts, these will work fine if you use a pair of each to get the right thickness. The Suzuki GS750 an GS1000 2 valve motors also have 10mm ID thick copper washers on the 4 end cylinder dome nuts too, because on the above motors all the top end oil goes up around the 4 outside end studs. Lots of modern late model motors have external oil lines routing the oil to the head now so that the engine oil does not get heated in the cylinders along side the pistons on the way to the top end. The XS has an external tubing oil line to the head up front in the breeze for the top end oil that has been unchanged since 1970.

  Most all other Japanese motors torque the 10mm X 1.25 cylinder/head stud nuts near 32-34lbs. I do the same to the XS motor studs (lubricated), the chart below shows the torque for the 6mm and the 8mm bolts that I leave at the recommended specs. 25ft lbs for the 8 studs that hold the entire XS cylinder, head, and cam cover assembly together is really a little light for the application. Heavy duty 10mm X 1.25 race studs that have rolled threads and are a full 10mm diameter across the stud length get torqued to 40 ft lbs.

Bob B.

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