How to remove snapped screw and/or back light

Got myself a new GRiSO, done 500 miles in past fortnight. 1st ride with mates today and the tail tidy snapped, looks home made. Took rear cowling off, kind of glad I did it now as the thread on front screw on right was very badly rusted, most of bike doesn't look like its seen rain. Anyway one of the 4 screws holding the tidy on from underneath snapped , any suggestions on how to get it out? I've started putting plusgas in the top of the thread hole. There is a bit sticking out, would it be better to cut a slot in it and try a flat head screwdriver or maybe file some flats on the sides and try mole grips. If that doesn't work maybe I can drill from above, in which case I need to get rear light off. Does it come off with mudguard when 4 bungee hooks and 2 allen screws are removed?
I am always a bit nervous working on bikes in case a screw or bolt snaps. This hasn't helped. Still will be ok when I have done enough maintenance on it to check and lube 'em.

a stud extractor may do the job. try heat first.

If you have the factory tail tidy, check out the installation manual to see what you may have to remove to get at the broken bolt.

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Thanks for the link to getting the cowling off. Doesn't tell you that in the manuals I've downloaded. I had already got it off but good to see it explained.
Now is there any manual for getting the back light off? workshop manual says take to a dealer.

I've done it, but can't remember (I'm old!). But IIRC, there is a cover for the wiring on the underside of the rear guard which is held on by cross-head (Philips?) screws. Undoing these plus the allen head bolt and nut holding the rear light for the rego plate, and you should then have access.

There are 4 cross head screws holding the back light on but they seem inaccessible. Looks like the whole under tray/mudguard and light would come off with taking the 4 bungee hooks and 2 central allen screws off.

Tried plusgas and a pipe wrench but no luck, only a small a bit of screw protruding which I reckon will just get more chewed off as it was stuck so tight

Or maybe I'll take back wheel off and drill from underneath. Only problem is I've only had the bike 2 weeks, don't have a service stand, so trying to get my head around how to lift rear to take wheel off. Thinking of strops to the joists, axle stands under the pucks (came with them but no stand) and a trolley jack to lift it. But where to place trolley jack?

You really need a way to hold the bike vertical while you jack it up but here's where you can put the jack with plank of wood to do work, and just need to adjust to get the balance right

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For the bolt removal I would use thread extractor and probably best you have a set for future anyway - best are the ones where you drill a pilot, hammer in the extractor, turn a/cwise to screww deeper and then remove. Trying to cut slots never works as the bolt will split easier than turn; and you'll be lucky to file flats on a stub end ....

Thanks Paul that’s useful info. I’m a bit wary of using a thread extractor after reading tales of them snapping off and being very hard to drill out, especially as the screw was stuck so tight. It was too long for the hole and reached the bottom of the tapped part before the head tightened down. I’m also a bit hesitant to drill in case I go off centre, thinking of borrowing a tap and putting a thread through the whole hole.

To be honest the extractor doesn't require a central or straight hole (I've done loads off center !); and as long as you don't go mad, it rarely breaks the extractor before the bolt breaks up (and leave you with another drill and extract attempt)......another extractor trick can also be to drill a bigger hole into the bolt all the way down. That usually makes it easier to extract (and allows you to use a bigger extractor which is less likely to break).  Drill and retap will require a centre dead/straight drill & is IMHO a much harder route to go.    I think removing shreaded bolts and sheared heads is a key skill for Guzzi owners; all part of the fun - see example on rear suspension axle with extractor off centre
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BTW can you send some pictures what bolt is buggered ?. Would make it easier to see the problem - we all like seeing other peoples problems

Haven't been able to post photos yet is there a "how to"

Just seen "can I post images" on FAQ, need to link to a publicly accessible web server. Could this be my own website?

If you have your own website I guess but easiest is chose a free picture site on cloud eg [You must be registered and logged in to see this link.] or you could use Onedrive or similar if you already use that . I think I went servimg because they suggested it here & took 10 seconds to set up. To post picture you can just klick host an image; select it on your laptop; send it to server; paste it into the thread....

Testing:

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found I had a flickr account, last used 2007

paulbrice wrote:

You really need a way to hold the bike vertical while you jack it up but here's where you can put the jack with plank of wood to do work, and just need to adjust to get the balance right.

I suggest that you invest in a front wheel stand, and tie the front end so it can't come out or topple. Then jacking up the rear becomes much easier and safer.

[You must be registered and logged in to see this image.]Untitled by a.p.griffiths, on Flickr

screw is bottom left

[You must be registered and logged in to see this image.]Untitled by a.p.griffiths, on Flickr

I have a front stand that lifts under head stem. Think I will try to hold upright with strops to joists and use jack under sump and suspension combined with axle stands under pucks.

That tyre needs more air.

ghezzi wrote:

That tyre needs more air.

I usually get "that drive needs weeding"

I think the mountain bike right front fork seal needs checking & one of the rear spokes looks a little loose - did you manage to take some pictures of the GRiSO ??

But seriously folks........If you don't want to pull the wheel off you could use 90 degrees electric drill bit and a 3 mm (it's a 5mm diameter bolt) drill followed by extractor as all that would fit in the gap. I just unscrewed mine using allen key so it doesn't seem to hold much tension (I fitted shorter tail tidy about 3 months ago). Personally wouldn't remove cowl/brake etc and drill from above as both the extractor and even a thread cutter would all require you going from underneath anyway.