Day 36 - Bad News

So....here's the latest....

The oil light flickering on idle thing is what I was last investigating so I hooked up an Oil pressure gauge in place of the oil pressure sensor and turns out the oil pressure is in fact really low. 

To this end, I've ordered a replacement Oil Pump, Oil pressure relief valve seals and oil strainer pickup seals and I've replaced the oil pump with one thats not so badly pitted and the clearances are all within spec.

I started up the engine and checked the oil pressure - same problem. It's still low. Really low, and today I replaced the oil pressure sensor with a replacement one, and still...the oil pressure light flickers at idle.

This leads me to one conclusion. This low oil pressure is due to either the main bearings or the crank pin bearings having way too large of a clearance therefore making the oil pressure low.

Today I also discovered another problem. When I start the bike now, there's a whole load of nasty blue smoke that pours out of the exhaust. This blue smoke goes away after a couple of minutes but this tells me that the valve stem oil seals also need replacing as I never did these and just left the old ones in.

So at this I'm not really up for doing another engine rebuild, and if I was to do this all over again I would have realised that you can't just take 2 halves of 2 different engines and put them together as there is going to be very small clearance differences between the 2 halves thus the bearings will wear unevenly between the 2 halves and I believe this is what is causing my low oil pressure problems. 

It seems inevitable that this rebuilt engine will die....eventually. I'll keep riding it until that happens / and then when it does it just seems more cost effective to get a replacement engine, one that has not has so much damage done to it and I can swap it out without too much agro.

I've learnt a few lessons from this project anyway...

1) Assume nothing!

2) If I've gone all the way to tear down the engine, then replace all the replaceables and don't leave the old things in! This includes main bearings / crank pin bearings and valve stem oil seals.

3) Check everything! I never checked the oil pump and only upon having this problem did I realise that I had to take the oil pump out again and saw how badly damaged it was - although replacing it didn't fix my problem.

4) Sometimes it's just more cost effective to get a replacement than to rebuild. Looking at the cost of new bearings from Honda + the time and extra work it is to tear down the engine it's often cheaper just to get another engine from another bike and replace it and be done with it.

So thats that. It was a good project. I'll ride the engine until it dies / explodes and then a replacement will be on the way.