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Re: valve guide seals for early 750 twins
If you have guides allowing to fit them there should be no problem. There is only one type of 8mm guide seals for the whole 750s range.
I think the original guides of early models didn’t have the possibility to fit them as they didn’t have a smaller diameter in that area. At those times many motocycles didn’t have them at all and it worked quite well I personally wouldn’t change the guides just for that. Aftermarket guides are only of the type that allows to fit the seals. ,,,
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this table will help you. I used to own one.. beautiful bikes easy to work on too!
Valve clearance: Inlet 0.13 0.19 mm
Exhaust 0.18 0.24 mm
Valve head thickness: Inlet 0.5mm 0.25 mm
Exhaust 0.8mm 0.5mm
Valve stem bend 0.05 mm TIR
Valve stem diameter: Inlet 4.975 4.990 mm 4.96 mm
Exhaust 4.955 4.970 mm 4.94 mm
Valve guide inside diameter 5.000 5.01 2 mm 5.08 mm
Valve/valve guide clearance
(wobble method): Inlet 0.02 0.07 mm 0.18 mm
Exhaust 0.06 0.11 mm 0.21 mm
Valve seating surface:
Outside diameter: Inlet 30.8 31.0 mm
Exhaust 26.3 26.5 mm
Width 0.5 1.0 mm
Valve spring free length: Inner 35.5 mm 33.6 mm
Outer 40.5 mm 38.6 mm
Valve seat cutting angle 32 degrees, 45 degrees, 60 degrees
Check the mating surface where the head meets the cylinder. Bad oil stains on the cooling fins in this area would suggest a bad head gasket. Do a compression check. Chances are the rings are bad or frozen to the piston from a long period of storage. In any event, the head would need to come off for a repair. So go ahead and stick in new valve guide seals and have the valves re-seated.
Oil in the cylinders mean worn rings or worn valve stem seals. You can try a blow down test to see if it is rings - get an old spark plug and bust out the ceramic weld in a fitting to press with air and air up the cyl. if you here air in the crankcase you have worn rings. You just have to replace the valve guide seals no test there.
The old design of slave cylinder (fitted to 2001 and prior bikes) wears badly leading to the unit drawing air in and ultimately loss of clutch action.
A new seal usually cures things but the housing itself can wear too, so this might also need to be replaced.
Alternatively the later, improved slave cylinder can be fitted, but this necessitates fitting of the later (longer) clutch pushrod.
Or, try one of the many "LARGE" piston type slave cylinders that are available. These reduce the lever pressure by approx 30%.
Bleeding process is:
bleed valve closed
open bleed valve - clutch lever will come in to bar - hold it!
close bleed valve
repeat till there are no more bubbles and operation is restored.