Power loss, clattering and seizure - EXPENSIVE OUTCOME!

[baileymc]

Okay. Following much anguish, NLM have put me out of my misery by providing a report on the engine within 24 hours of it being deposited in their workshop. They'd never seen a crank and big-end so chewed up. apparently, it's worthy of putting on a plaque!

One big end was oval and the crank journal was much reduced and blue. The white metal bearings had gone completely, and the piston had lost much of its skirt while crashing around. The piston had also been hitting the head, but they think I've got away with it. I expect a diagnosis on the valves and guides quite soon. Amazingly, the other con-rod and piston were okay.

Outcome is a new crank, con-rod and piston inc new shells. The bores were okay (slightly oval) but as I need new parts I've decided to go down the 375cc route with a rebore and new pistons. I can also get various other improvements such as roller bearings and gas flowing made to the engine at the same time.

An expensive lesson learned i.e don't expect too much from a cheap ebay purchase without a full service and MOT history. It'll cost you more in the long run.

The cause would appear to be normal wear and tear (the oil pump is fine), but lack of use by previous ownership may have played a big part through moisture retention in the sump corroding bearing surfaces.

Keep your bikes on the road to keep your money in your wallet is my advice! See you at Cadwell in the autumn with my 3 3/4

Martin

[robinh44]

Martin

Thanks for the update, ouch!!. Glad you at least get the 375 big bore as a bonus for all the expense. Makes me worry about my Kanguro laid up for the last year under cover in my back garden whilst I rebuilt everything but the engine. Did a test run recently and it sounded ok. I will check the oil colour when I drain it off.

Regards

Robin

[baileymc]

Thanks Robin. My 3 1/2 had been sat in a damp shed for several years, only doing a handful of miles a year. Damp is always a worry for external surfaces never mind internal ones so I guess that it really pays to use your Morini regularly. Mine also had the indignity of half a tank of petrol in the sump as the previous owner left the manual taps open: fuel gradually filtered down through the cyninders diluting the oil. Heaven only knows what that did to the oil and bearing surfaces when he was riding it to shops!

Like many classic enthusiasts, I'm in my 40s and prefer the bikes that I couldn't afford in my teens. Back then you had a bike that was a few of years old, was used every day of the week, and hadn't suffered the ravages of time through storage. They were more robust and reliable through use. 25 years on, many are much more susceptable to mechanical damage.

My recent experience just goes to show what can go wrong if you just strip down the top end or clutch and hope that the bottom will be fine 'cos it's bathed in oil and there's only 20,000 miles on the clock. If your bike hasn't been used regularly for a number of years I'd recommend stripping the engine right down if you have it out of the frame for other work.

I'm sure yours will be fine.

Cheers

Martin

[Ballacraine]

Well, as has been said already, at least you are getting an upgrade out of your repair.

My bikes may not be used that frequently, but every time they are taken out, they get a 60 mile plus run. I think this is the most important factor.
The oil gets changed once a year and I never see water contamination.

Unlike the horrific state the emulsified oil was in in my Cali when I bought it with less than 3,000miles on it. It was only ever used on short trips by the late previous owner.
I'm just hoping I caught it before any permanent damage was done.
Big block Guzzis are robust old lumps, so I am hoping all will be well.

Nige.

[baileymc]

I couldn't agree more. Speaking from experience (!), infrequent short journeys and poor attention to oil and filters is asking for disaster.

All the best, Martin.