Saving Old Seagulls

A measurement of the height of the flywheel centre may prove instructive.

Thanks for all the replies everyone.

Crank measurements:

My top crank measurements come up slightly under? If they were the same the flywheel would sit even higher (!). However, I have seen differences between cranks before. I have a Century crank, which is approx 4mm shorter overall.

18.82 - 14.4
33.19 - 28.0
41.11 - 37.5
8.16 - 9.8
12.43 - 11.3
7.41 - 6.9

The lower measurements seem to be the same

6.31 - 6.4
34.76 - 34.1

Flywheel measurement

Slightly lower, between 45.1mm and 45.5mm

Oysters pics:

"These are my two SDs, plus a pic of one now sold. Quite a variation between the three" - yes quite a bit!

I forgot to mention my SD has no locating 'dimple'. If I move my base plate up a bit, it looks very similar to Oyster's first pic. I imagine I'll have to somehow set the timing manually?

I seed no evidence of the crank-case being machined / altered. My crank-case doesn't have "Seagull" cast into it, so I imagine it is an earlier version.
The washer seems a like a bit of an later bodge. The inner diameter doesn't match. Furthermore, it is uneven and wobbles when the base-plate is installed above.

I'm hoping that I just have a particularly 'high' sitting flywheel.

I meant the height of the one that has the washer - I'm wondering if the bashing around the rim may have flattened the dished top.

Looking at that crankcase casting, it does not seem quite "right" if you know what I mean. There are differences in the detail of the casting. Could you actually have a pre SD pair of crankcases there? This is a picture of a SD upper crankcase half, spot the differences? The lack of "Seagull" cast into the case is intriguing

Hmmm. I don't know. Here are some more pictures. The cases certainly seem to match; maybe they were left over pre SD?

Maybe pre SD the crank was slightly different- hence con-rod bolts scraping on the inner crank-case?

There's another question for the SD registration form.

My SD is only about 300 away from yours, it is also an L3.

There is no seagull on the crankcae on mine.

Perhaps the 3 after the L means something, could be a different factory perhaps.

Does yours have the Skeg stamp?

H-A

Hi, yes mine has a skeg stamp: "CIESS <- G 232", gearbox stamped 35, gearbox cover stamped 34.

I'm actually replacing this box with one from Oyster. The gear pinion was badly chipped

charlesp wrote:I meant the height of the one that has the washer - I'm wondering if the bashing around the rim may have flattened the dished top.

Sorry Charles, missed your post. Height of flywheel center is 60.1mm

My early (125) also has seagull on the case.

No washer just the..... BUSH......