Time for another oil change

As usual, click on any hand-drawn and crayon-coloured image to zoom in.





There's not been much happening over the last few weeks. Surprising really, given that it's Summer but there you go.


I rode over to Mark's this afternoon though to do an oil change - it's been just over 500 miles since the rebuild so we put some new mineral 20w/50 oil in the Mario Mobile and Luigi put some Morris Golden Film in his before we popped out for a 40 miles jaunt in the sunshine.

New head gasket

As usual, click any image to zoom in.

It’s been sunny for weeks and today it decides to rain. At least we were able to work in Mark’s garage while we replaced the head gasket on his C15 to try to cure the oil leak.

It seems a little better now in that the top of the crankcase and the vertical part of the exhaust pipe are now dry, but there is still a leak from somewhere putting a light film of clean oil on the front of the gearchange rubber, the bottom half of the crankcase (below the gearchange lever) and the vertical downpipe of the frame on that side.

RTS engine quote

The bill for my engine rebuild will be £850-900 ish. That includes new alpha big end, main bearings, rebore, new piston and rings, valves and springs etc, plus cams and larger inlet valve.  I'd hoped it would be around £750:00 but I suppose the cam and inlet valve modification are worth the extra.  I see no point in doing so much work on the engine, knowing that the head needed sorting out, and not completing the job properly for the sake of £150:00. 

At least the bike will be up to spec apart from the front forks and indicators. We can then fit the indicators and put some oil in the forks and see if any oil leaks and, depending on how fast any leak might be, that will help me decide whether to just keep topping the forks up, or consider having the forks repaired!

Engine rebuild

As usual, click any image to zoom in.

After a few people taking a look at my bike and saying it sounded OK to ride, I could still hear a knock so we took the engine out and the head off. Lo - the conrod was waggling about when you tried lifting it.

Not fancying trying to repair it ourselves, we found Roger Taylor of RTS Racing while searching on ebay for some spare parts. We dropped the engine off with him today in Gloucester and he reckons that even though he's really busy at the moment, he can turn it round in 2 or 3 weeks.

On another note, Roger explained that the oil return on my other engine sounds fine because the return flow rate is higher than the inbound flow - this is why the initial return rate after starting the bike is excellent but then settles down to a slower rate, even with the odd bubble.

BSA C15 lubrication

As usual, click any image to zoom in.

If I start my bike up then the oil return is healthy for a few seconds but then reduces to the odd spurt, blowing big oil bubbles. If you turn the engine off, wait a minute and try again, then the same behaviour occurs. This would seem to point to the oil pump being OK, especially given that it is not wet sumping.

At first we thought it might be a problem with the return flow of oil but we're now beginning to suspect that it might be that the oil isn't flowing into the system quickly enough. Hopefully it is not the feed non-return valve as that means splitting the crank cases and replacing it.

There is a good description of the lubrication system on the Classic Bikes web site:

Oil change

As usual, click any image to zoom in.

We changed the oil in Mark's C15 today.

We ran the bike until it was warmed up then drained the oil tank and cleaned both the oil filters before filling back up with 20w50 mineral oil.

To stop an oil leak we've tried replacing the metal washers on the sump plate with some fibre washers.