Modern Vespa

I have noticed quite a bark under heavy throttle coming from the engine and it appears to be the exhaust gasket leaking. Is this a common occurrence (mine is a 2020 with about 12000km)?

What is the easiest way to access the head stud nuts (other than dropping the engine out)?

ahh ....

do you mean the bushing / gasket where the exhaust meets the header? that does fail and is easy to replace without touching the head studs.

or do you mean the copper gasket where the header meets the head. I've never heard of that failing ...

Good question, thanks!

I think I should be starting with a new joint gasket and see if that fixes the issue. I checked the exhaust stud nuts and they were tight so I agree it seems less likely to blow from there.

12,000 km is a good distance for that graphite collar to last. Buy two - you will always need a spare.

So I purchased a new exhaust gasket (the graphite sleeve) and installed that. That has made no difference so I will need to move further up in my leak hunt. The old gasket was in pretty decent shape when I extracted it (but of course extraction destroyed it).

Is there any sensible way to position the engine/chassis to make accessing the header stud nuts more accessible?

No. swivel join is needed for one of the nuts. Other should fine.

Robot/scooterwest has a video on installing an akra on an hpe. Watch that

Great suggestion regarding the video, thank you. I have swivel/wobble bits (to be clear, I am referring to my tools here).

I think we all have some swivel/wobble bits, and also some in the toolbox. 🤔🤣

You can actually lay it down almost all the way on its left side without harm, as long as the engine isn't running. You just need to keep the oil sump lower than the valve cover breather pipe - or be prepared to clean the air filter when done.

I finally got around to buying a new exhaust gasket and dropping the header off the bike. The old gasket was great, not so great was the big crack in the header pipe. At least I know I was looking in the right place.

What is the consensus?
-get the pipe welded (crack goes >50% of the circumference)?
-just buy a new part?

you appear to have an aftermarket sports exhaust. it's not unusual for the header to crack when using these (happened to me). I suggest replacing with a stainless steel header - can get from the usual places like SIP, Falan, Scooter Center (can't find on scooterwest). also on ebay and aliexpress

https://www.sip-scootershop.com/en/product/exhaust-manifold-sip-842683-1a007653-for-vespa-gts-gts-super-gtv-gt-60-ie-125-300ccm_842683VA

https://www.scooter-center.com/en/exhaust-manifold-bgm-pro-stainless-steel-to-be-used-with-lambda-sensor-vespa-gt-250-zapm45102-vespa-gts-250-zapm45100-zapm45101-vespa-gts-300-zapm45200-zapm45202-zapma3300-vespa-gts-hpe-300-zapma3600-vespa-gts-super-300-zapm45200-bgm0052

https://falanparts.com/products/exhaust-manifold-101-octane-stainless-steel-vespa-gts-gtv-gt-125-300cc

Depending on the material, a good TIG weld is harder than anything else. If it were my bike, and with the current wait times for parts, I would just weld and be done with it.

Thanks for the advice gentlemen. After some online price and availability checking I took my pipe to a local exhaust repair shop and got lucky on a Saturday morning, found a craftsman who did a while-I-waited repair and then declined payment! I gave him some cash for his trouble.

I didn't know Racing Planet makes this part. Now it's back on the menu. Learn something new every day.

now that you have it repaired go ahead and get the SS one a coming. cause it will crack again.

Duly noted.

guess this is kind of a common problem, as i did the same fix to mine.....have not cracked again....sweet cheep fix:)