Honda-SOHC

Hi Guys,
I mentioned when congratulating Nurse Julie on her Engine Rebuild thread, and on my "Splitting the crankcase problem" thread, that I was was going to investigate a mechanical "Screech" sound that lasted for several seconds after resarting the bike while it was warmed up after my second ride.

My hunch from my experience, was that it sounded like the main bearings were tight and could seize up if not rectified.

Recent History
The PO had carried out a full engine rebuild with the majority of work done by an engine specialist (THIS WAS NOT TRIG AND JULIE I must emphasise), just leaving the PO to do final assembly. This work was done in 2015 and the engine has run 3000miles since. Advice on which shell sizes to use on which journals was made by the specialist.

Having experienced the noise I consulted the PO who thought it might be the timing chain adjustment, but this "Screech" sound was far too solid and friction sounding to ignore. I decided NOT to run the engine again and do a full strip and inspection.

Having just split the casings and inspected the journals and shells it looks as though the centre bearing has been the main offender with journals 2 and 4 not far behind. See photos. In the order of 1 to 5.

It was noticeable that 2,3 and 4 had little oil film on the crank or the shell (oil squeezed out due to lack of clearance)and you will see the highly polished face on these journals and shells. Compare these with 1 and 5 which are relatively unpolished and wet with oil, showing  that a good hydrodynamic film of oil was  present to "float the bearings" 1 and 5 rather than grip them.

I think this has only shown up because of the heat sinking and oil draining from the heads and barrels after a ride causing the extra heat transfer and differential expansion on these components at the time, and the fact I started the engine again shortly after.

Journals 2,3 and 4 will now come under closer scrutiny with Plastigauge measurement to see the actual clearance measurement.

To be continued as time allows.

Dennis

PS my next post will show the Shells 1 to 5
 

Hi guys, I am looking and wondering if there is a reference list to cover all the "O" rings and seals needed for the Engine Trans unit. I am trying not to make assumptions about what is included/ excluded in gasket sets etc, although there is a sealed bag full of "O" rings.

From all the rebuilds you have carried out between you, there is lot of experience of  Which things are included AND Which things need to be ordered seperately. There are odd things like the starter motor O ring etc I wanted to include

The bike I purchase recently has a few minor oil leaks to deal with, so I have decide to do a full strip and inspection so I know the full internal condition.

To have this info available woud be most helpful prior to ordering, also knowing best where they can be obtained and  which brands are reliable and those to avoid.

Cheers 

Dennis