Modern Vespa

Did a oil change on my gts 300 2011 , the sump plug was really tight to get off, now when I tried to put it back on it goes tight but then it goes loose again, so I've tightened it as tight as I can , it's not leaking will it be ok , is there a way of fixing it? Cheers

It will come loose again at a very in opportune moment. It could be catestrophic as it will dump oil all over the rear tire. It sounds like the threads are stripped. You'll need to fix it. You might be able to get an oversized self tapping plug or you might want to install an insert to repair the threads and bring it back to stock size (that would be my choice).

Bought a helicoil set when I had to do mine. Came with drill bit and tap in it as well. Not sure if it was M10 or 12 though. Worked great.

What caschnd1 says is spot on It will go again for sure and if you are riding at the time It doesn't need thinking about, don't ride it till its repaired, hot oil, rubber and tarmac don't mix, it needs re threading, Heli coiling or an oversize plug by a competent repairer, reason being you need a guarantee on the repair.

Does anyone know who could do this for me in the West Midlands Shropshire area?

A friend of mine caught his sump plug on a Kawasaki 1300 on the ramps coming off the IOM ferry. He was about half a mile from the ferry terminal when his rear end became "loose" .

So on day 1 of his holiday he had to get his sump helicoiled and a new rear tyre as the old one was ruined.

All this on a bike with 180 bhp at the rear wheel, it could have been much much worse.

What was wrong with his rear tire?

you are so not going to want to hear this... but you're kinda hosed.

sounds like the threads are stripped and it's just-t-t holding on. so here's a few ideas from proper fixes to ghetto fabulous:

>try another drain plug and hope that the new sharp threads will catch it'll snug up.
>secure a tap and clean up the threads
>clean everything really, really well, and then seal the thing on there with a two part epoxy like JB weld or devcon.
>remove the engine, have it welded and re-tap the threads
>tap it out to a more common 28X1.5 size

so, here's all the complicated things and stuffs:
>the size is 28X1.0 which is its own entity. there are taps out there floating around, but it'll be at a specialist shop or thru a guy that knows a guy that knows another guy. start making some calls and be prepared for everybody to tell you that you're screwed and you'll need to replace your motor.

>tapping out to 28X1.5 is not a big deal there's plenty of meat and there's tons of plugs available. however, the filter screen sits behind the plug and nests in the cut out center. so you'll either need to machine the new plug so that the filter screen has somewhere to sit, maybe trim the tang off the end of the screen or just run without a screen.

>pulling the motor and having it re-welded and machined for a fresh plug will be incredibly expensive. like, go get a new used motor expensive.

>slathering that thing up like Betty Crocker is a last resort. but it's been a proven repair for many a bike. you just need a vacuum pump to change the oil thru the dipstick hole.

try a new plug first and hope for the best.

The oil had completely soaked in between all the treads. He was over for the TT and regularly takes his bike over the circuit at a gps speeds of 180/190 mph. Everything has to be perfect, so he didn't want to compromise or risk any issue with unseen contamination.

Ironically the bike had new tyre and pads for the TT. On his new H2R he can go through a tyre in two or three days at the TT 🤦‍♂️

Ps I was wrong with the cc in my first post its a ZZR1400 not 1300 duh !

Thanks for all your comments, I've had it re tapped, just got it back, just in time as I'm going to France and Spain on Friday 🛵