Unrestored 102 SD (Naval?)

[charlesp]

Almost everything was contracted out, as far as I can ascertain they only assembled the motors.

[Charles uk]

That would explain why they had to redesign most of the components, they didn't have the patterns or the tooling or the machinery to do the machining, all this development would have to be paid for, hence turn all our spares into motors & sell them.

Would all owners of Cs & Ds care to post their engine numbers & their basic motor details in the same format that I used, so we can all understand.

[Collector Inspector]

"Bailey"

Real cool name!

B

[Oyster 49]

So has the strip down commenced?

[Beagle2]

Wow what a lot of reply. Intersting points.

I've started the strip down. All coming apart quite well so far. I've left the powerhead alone as I want to order a flywheel remover from SOS. I've stripped the carb. Looks in good order with solid threads. Although I think the red washers need replacing. Are they available? Or do people make their own?

Unfortunately I've got to go abroad with work for a few weeks, so I won't be able to post any pics till I return.

Many thanks

[Beagle2]

I’ve started stripping down the powerhead. Most things have come apart easily, nothing seems corroded.

Overview

The carb has come apart nicely and was very clean inside. Just needs a washer set and a brass trumpet to finish.

However there seems to be some issues with the crank/rod/ piston…

There are 3 main problems

1) Something doesn’t seem right with the big-end bolts. One is worn at an angle and there appear to be gouges where the bolts have hit the crank case. (see pics)

Crankcase Issue 1

Crankcase Issue 2

Worn bolt

I have reassembled it and it is very fiddly to make the crank rotate freely without the bolts hitting into the crankcase. It’s almost like the both need to have angled edges/ a lower profile.

Crankcase Issue 3

I didn’t try to rotate the engine before strip down as it appeared to be seized.

The piston is marked "STDG" (standard?) on the top and Heptolite on the inner. It also has gudgen circlips. The rod is marked “Seagull 1”. Is this correct?

[Beagle2]

2) The end float in the crank is about 0.7mm. This seems a lot to me, but according to previous posts is nothing to worry about?


3) There are some signs of corrosion on one end of the crank. Should I worry?

Crank marks

Forgot to post pics of piston:

Rod

Piston

[Oyster 49]

I'm wondering if you have a incorrect crank or conrod there? Something does not look right, I'll get another crank and crankcase pair out tomorrow to compare it to. The gudgeon pin should have an aluminium cap on each end I think.

Charles UK will probably be able to help also, also loads of SD pictures on this forum, just search for them.

[Keith.P]

looks like a century conrod?

[Beagle2]

Thanks guys

Re. the Rod, that's what I suspected. It looks too new.

The piston didn't aluminum end caps, just circlips either side of the gudgeon pin.

A bit worrying !

Currently looking through prev posts for a picture of a 102 SD con ron. Can anyone point me to a thread?

[Beagle2]

download/file.php?id=686&mode=view

This is the best pic I could find. The piston might be the same but the rod looks different.

What parts powerhead parts are interchangable between the short water jacket and the long water jackets?

I ask as I have a sound AD powerhead at home (somewhere).

[Jan]

At this moment I'm working on a SD with broken crankshaft.

There is a 3 - 4mm gap between the conrod cap screw and crankcase.

Piston and gudgeon pin with aluminium end caps, no circlip grooves in piston

Jan

P.S. I found a good SD cylinder and piston if you can't find one in the UK.

[Oyster 49]

I have a rusty SD crank which is spare, but the con rod seems ok. You are welcome to it if you need one. I'll dig it out to check the condition.

[Oyster 49]

Just double checked, the con rod is actually broken.

I do have a AD crank with a good con rod, if that is any help.

[Beagle2]

That would be great if it's compatable Oyster. Pm me prices and postage etc.

I'm still slightly confused why there is a Century rod in an SD. And I'm not sure if my crank is original. It looks similar to Jan's but has smaller, neater welds on the counterweights.

I imagine previous owner used whatever rod was available, unless there is some sort of performance improvement. Assuming the crank is original the piston datum would be raised. Is there any (believed) change in performance from doing this?