Scooterotica

If you use Allen head bolts instead of studs for the chaincase how long do they need to be?

Some think it not a good idea to use bolts instead of studs because thread wear in the chaincase. I suppose it depends on how often the chaincase side is removed

Yes I read that but I also saw that some late Italian models used bolts, I did a measure of studs and holes and I reckon 25mm for the M6 and 35mm for the M8, M6x 30mm for the exhaust tail pipe

the hard steel will wear the softer alloy threads.
The steel can cause galvanic corrosion - again damaging the casing threads. Be very careful using stainless steel- Search steel bolts in aluminium casings.
Lastly - as the threads wear they become loose and easier to cross thread.

Where I do have to use steel bolts/screws - I use low strength thread lock to try and create a barrier between the steel and alloy - like loctite 222- it’s not perfect but seems to work.

The standard studs are high tensile steel so most of your post is not really relevant.
I’ve used black anodised steel bolts so the effects of galvanic corrosion should be minimal,
Thanks for your input though

back in the 70's my pal re-tapped his chaincase to a coarser Whitworth thread and used bolts without any problem.