Rebuilding motorcycle after timing chain skip 62K Km

Getting warmer, spring is coming. I think there is a way to separate the cylinder block from crankcase by removing gudgeon pins ang lift the block with the pistons inside while leaving conrods connected. I don’t have to crack the crankcase open but just level the cylinders and lift the blocks until the pins become visible through scallops. I need new circlips and a tool to remove them. Anybody disconnected the pistons to tell how stiff the circlips are? I need to work in a tight space at 90 degrees with the pistons half exposed.
 

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Got courageous and pulled the cylinder block. The pistons and rings are filthy. The chain seems stiff. There is no access on the bottom on the crankcase to remove condos, only thin slots to drain the oil. It is not possible to work on condos or crankshaft without splitting the crankcase in half (after you remove the sump).
 

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Dipstick tube o-rings are broken. Seems like assembly error - I am not aware of any dismantling operation until now. one chain guide bent and offset (maybe this cause the annoying rattle when hot?!?!).
Piston rings are soft at this diameters, I will try to insert the piston from the bottom; the chamfers of the scallops seem ok. I need to study how to lower the barrels on the pistons after I clean them thoroughly. Before starting this I need new circlips and thorough cleaning of everything.
 

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Nashvegas said:
Great pictures! I don’t know if I will ever get bold enough to break an engine down this far, but it is very interesting. Thanks!
Click to expand...
I would also advise against it unless one needs to rebuild it completely, for example as regular maintenance for all bearings and piston rings and cleaning everything up. The engine is built in layers like an onion and it doesn’t make sense to tear it apart for no good reason. It could have lived for two years more if I didn’t bend the valves.
  • 62000 kilometers, Penner tune, ridden aggressively. Carbon deposits on pistons and valves. I reckon could have waited for 100000-120000 then it may start losing breath.
  • Secondary air injection, reed valves, filthy. Asphalt-like deposits on it.
  • Shaft quite clean, splines in good condition, never lubed.
  • Clutch started screeching at about 52000 kilometers, then seized occasionally. Replaced. Marks on hub left alone, to attempt to grind them.
  • Exhaust - catalytic converter box - rusty, shield clamps rotten almost falling. Poor quality thread on welded nuts. Two seized bolts, had to drill them out.
  • Exhaust manifold spot welded nuts- poor quality thread. One nut fell off, so welded all six, drilled one and installed a sleeve.
  • I will replace timing chain and sprockets.
  • Still anxious about the valve lapping. I don’t want to open it again soon.
  • Good to do everything in one go and save for parts years before. If you pay somebody, save longer. By the book, cannot clean pistons without removing the barrels. Which requires splitting crankcase in half to remove a splitter just to see the crankshaft to dismantle the conrods. Before that you need to remove the sump, of course. And the head, of course.
In conclusion the tank works well and may need a deep bath and some preventative maintenance every 100000-120000 kilometers. Can do more but then you may need to clean more later or replace some bearings.
 
New pictures, fantastic adventure. One piston seems to have rings stuck. Its cylinder has strange marks. Got new pistons and rings. Waiting for a new cylinder block. Fixed the cracked front frame lug with 3M DP420 (used to glue mountain bike frames). Medical grade process (wash, degrease, grind, degas, degrease, glue). In process of designing a reinforcing filler. Bridge arch like I guess.
Info: R3GT cylinder block is supplied by Gilardoni, also a Moto Guzzi supplier located in the same area in Italy. Gilardoni don’t work with individuals, but aftermarket replating and honing can be done with others in Europe. Reworking with all shipments is almost twice the amount of a new block so…
 

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