Hello All,
Hope you're all ok in these troubling times.
Well, Engine now stripped and forensic investigation (to date) completed.
Confirmed - A previous owner had had a full bottom end and barrels Rebuild done by SRM, new high capacity pump, SRM piston type PRV, end feed crank, s'trap cleaned and hex plugs fitted, dynamic crank balancing, SRM roller+ball timing side bearing conversion, billet rods, barrels blasted and stove enamelled, bores taken out to +.060, new SRM cam and followers etc, - lovely job.
Recap on earlier issue and actions - Engine smoking very badly so top end stripdown - Bores found badly scored so honed true and new pistons + rings fitted. Head cleaned and checked, valves re-seated, new SRM tappets.
Top end rebuilt. (Honing took bores to just beyond limit for +.060s and rings, my decision to try it).
Static test run confirmed still smoking, possible problem with oil scavenge/return side.
Latest Findings - Big end shells badly worn and scored with excessive clearence. Some debris in the sludge trap.
Detailed checks on:- Cam, cam bushes, followers, rods, bottom end bearings, crank bearing journals oil pump, PRV, - Show all are ok.
Crank big end journals showing some surface scoring.
Conclusion - Superb bottom end and barrels rebuild by SRM ruined, most likely by subsequent use of detergent 20w 50 or similar oil (guy I bought it from said that he was using modern 20/50 in it), and running it without first cleaning out the oil tank, that's the kicker.
Thank heavens previous owner didn't use it much and that I thoroughly cleaned out the oil tank when I got the bike, plus its fitted with a cartridge oil filter, which limited the damage.
Now to thoroughly clean out or replace the oil lines and all of the oil galleries. Replace valve guides, replace all oil seals, get the bores sorted properly, clean out the oil tank (again), re-check everthing and then rebuild.
Will take time to get all of this done, so next instalment will be a while away. Great how all of the old A10 experience has come back, helped a lot by your suggestions and ideas.
Thanks and stay safe guys,
Dan.