Plastic engine case really necessary?

Been trying to change the throttle cable on my aprilia sr 125 2t.
I've gone to take the plastic that covers the engine casing off and noticed 3 of the bolts are rusted in.
Not budging!
So my question is, is the plastic cover needed?
Or can I just snap the bolt heads off remove the cover and just ride with the engine casing on show?
Seems too much work drilling and re-tapping bolts just to put a bit of flimsy plastic back on.

 

If they have them from factory, There's usually a reason for it. I believe the plastics have something to do with helping to circulate air to help cool the engine. If it's a water cooled engine it would be fine, Air cooled - I wouldn't leave them off.

 

Aircooled shroud directs air from the forced air blower around and over the head and through a couple vent slots in the other side.

without a shroud the blower fan is useless its not going to have a cooling affect on the motor, the faster the motor turns the more faster the fan blades run and the more air is pumped into the shroud, removing this shroud means the motor has to cool itself without added help and its impossible in that enclosed engine bay even with open bottom, the belly pan will direct air away and not force it into the bay area.

 

So by the looks of things this is going to turn into a bigger job than expected.
How hard is it to remove bolts that are rusted in without damaging the thread to the point where I can't replace the bolts?
I wish one of you geniuses lived local so I could just put my money in you're pocket rather than some mechanic who makes a small problem seem like the end of the world. Lol

 

treat them a few times with penerating lube like wd40. do not try and crack them on the first lube, so treat em, wait a good half hour or so, treat em again , wait another half hour or so, treat em a third time.

if its a bolt you could try to tighten it before trying to crack it loose, BUT there is the chance it could bust off. an impact gun may be a better choice if one can get hands on a device.

mech did my exhaust today impacted the exhaust bolts off and removed a stub instead of the nut lol some are just stubborn as hell until they get some meat on them. impact gun gives them a jolt like hammer as it cracks them undone , a spanner/wrench is just forcing them undone

 

The mechanic told me that 2 screws that hold the engine shroud on will snap if you were to put force on them.
He said because of this the engine case bolts could be the same and it could result in hours and hours of work.
I think he is just trying to make the job last longer to be honest.
I spoke to a friend who does metal work and he said he can sort it out for me so I'll leave it to him.

 

The plastic transmission cover in not essential remove it and fit a typhoon air scoop. Alot of people (including me) remove the plastic cover and then polish the casing and fit the typhoon scoop. Your bike will not overheat if it's removed now if you remove the cylinder shroud that would be a whole diffrent story. The aluminum casing under the plastic cover has "Piaggio" molded into it i doubt Aprilia wanted that on show (it's covered on runners too) i know the cover is also there to aid transmission cooling but the typhoon scoop does the same job and looks alot better in my opinion.

 

Thanks for the advice man.
I'm going to check out the Typhoon scoop you're talking about 100%