SIP GS piston gudgen pin failure

[ArmandTanzarian]

My rally developed a bad vibration on the over run I thought it might be the crank but it turned out that the case hardening on the gudgen pin had failed and worn a neat trench around it. Lucky I checked it as I'm about to ride 1500 miles! I'll post a picture when get home this evening.

[ArmandTanzarian]

So much for high quality German parts!



I think I caught that just in time!

[Yanker]

Well caught! Looking at the 'GS' offerings my mind leads me to think that the production may be in fact in Italy (Meteor)?

[Muttley McLadd]

It's only half of it. Can't you just turn it round?

[gaz_powell]

Probabaly further away than Italy ......and are Meteor made in Italy or packaged in Italy

I bought a FA Italia bagged Vespa flywheel side bearing - opened it up and it NRB !!

Theres a glut of P2 piston on the market from India at the moment - so they are been produced out there.

MEC are the same i believe made

Got a GS piston ready to go in my top end ....... also got a genuine Piaggio ........ i know whats going in now - files out tonight to match it barrel.

I`m sceptical about most things now ....... BGM been one of them - Germany Technology .........

Gaz

[Speed Demon]

I'd be really surprised if that hasn't taken out your con rod too. Looks like a lubrication (or lack of) issue.

[Muppet]

I'd be really surprised if that hasn't taken out your con rod too. Looks like a lubrication (or lack of) issue.

+1

[gaz_powell]

interesting afternoon in the garage

decided to do a back to back test of the sip road against the performer on my bike - had a good blast to IOW using the performer (which has been on years) so I knew what I was looking for - no issues with bike had a good fast ride there and back over 700 miles.

Top end is a mildly tuned autisa with meteor piston on 66.7 bore done with 4 thou + clearance (done around 4-5k miles)

before straight swapping of the pipe I thought I would have a look at the top end.....................

top ring gummed up and gudgeon pin the same at the one pictured but not as deep - con rod is fine

I use 2/3% Exol Semi

crown was good but evident it was running a bit rich

stripped it, cleaned up, new rings, new gudgeon pin, new small end and rebuilt with sip road

I think the gumming up maybe excess bore clearance as at the last rebore it was suggested to take it out to next o/s but I didn't want to loose a bore. The barrel liner is soft - will see how it goes.

will have a look at the jetting with the SIP Road

But the gudgeon pin .....need to have a think about that

Gaz

edit - its thrashed every where and has never had a sniff of a seizure

[ArmandTanzarian]

After swapping out the gudgen pin I went on a 7 day, 1600 mile trip around the UK and Ireland. I stripped it down today and the pin is as good as new. I'm guessing that it was a manufacturing fault with the hardening.

Like yours, mine was running a little rich but not excessively so. The rings, as mentioned in my other posts were gummed up. The barrel was rebored and an oversize piston fitted about 3000 miles ago and so that should all be within tolerance. I think it might be time to try another oil.

[gaz_powell]

be interesting to know who makes the GS pistons, mine was meteor and it was suggested that they maybe the same

ive been running exol on my GP and SX - GP was stripped beginning of year after a year on exol and no issues
SX due for new rings and reeds at end of year so we`ll see

Gaz