Righto,
Acquired '87 R80 RT 'project' quite some time ago. Ebay. Complete rolling chassis all sorted with new bearings, wiring and stainless screws everywhere. All powder-coated and looking lovely, not so keen on the cast wheels but hey maybe I can deal with them some other time. Tank and mudguards all present. Came with spare tank and boxes of bits. The engine was not fitted but had been thoroughly cleaned with the heads, barrels, pistons and valve gear all separately bagged and marked as L/R side. These items had also been thoroughly cleaned.
Straightforward then?
Not quite. Eventually make a start, order up gaskets, seals and O rings amongst other stuff. Fit new main seal and clutch. Mount engine and proceed to assemble top end. All goes well and pretty easy really. Torque it all up and (minus plugs) back off rocker arms and bring cylinder to TDC on compression stroke. Check timing marks and all correct. OT shows in the window. Set the clearance at 0.1 and 0.2mm. So, I start turning the engine and the exhaust valve begins to open and then stops! Spring is fully compressed even though valve is not fully open. Bring it back to TDC and check everything. All correct. Start again and the same thing happens. After many repetitions and checking timing etc the engine will only turn over with valve clearances at around 4mm. I know. With the correct valve clearance any attempt to turn the engine through its cycle results in full spring compression before the cycle is complete. This happens on all valves.
Some of the best brains in S London have stood in my garage perplexed. Top end has been disassembled and everything measured. All comes up to spec, pushrod length, overall valve height, spring height. The cam is correct and seems unmolested.
Any ideas as November 5th isn't too far off?
Acquired '87 R80 RT 'project' quite some time ago. Ebay. Complete rolling chassis all sorted with new bearings, wiring and stainless screws everywhere. All powder-coated and looking lovely, not so keen on the cast wheels but hey maybe I can deal with them some other time. Tank and mudguards all present. Came with spare tank and boxes of bits. The engine was not fitted but had been thoroughly cleaned with the heads, barrels, pistons and valve gear all separately bagged and marked as L/R side. These items had also been thoroughly cleaned.
Straightforward then?
Not quite. Eventually make a start, order up gaskets, seals and O rings amongst other stuff. Fit new main seal and clutch. Mount engine and proceed to assemble top end. All goes well and pretty easy really. Torque it all up and (minus plugs) back off rocker arms and bring cylinder to TDC on compression stroke. Check timing marks and all correct. OT shows in the window. Set the clearance at 0.1 and 0.2mm. So, I start turning the engine and the exhaust valve begins to open and then stops! Spring is fully compressed even though valve is not fully open. Bring it back to TDC and check everything. All correct. Start again and the same thing happens. After many repetitions and checking timing etc the engine will only turn over with valve clearances at around 4mm. I know. With the correct valve clearance any attempt to turn the engine through its cycle results in full spring compression before the cycle is complete. This happens on all valves.
Some of the best brains in S London have stood in my garage perplexed. Top end has been disassembled and everything measured. All comes up to spec, pushrod length, overall valve height, spring height. The cam is correct and seems unmolested.
Any ideas as November 5th isn't too far off?