Yes. Not 11 years, only 10 years, you can smear the gasket residue with a thinner, It will softened the gasket residue. You need to work slowly and patiently to avoid two types of damage:
I had an entire new crankcase cover to put on I was trying to take what stuck to the engine side off which was a bit tricky but like you I ended up using a razor blade and carb cleaner to soften up the tougher parts. My plastic scraper just wasn’t working. It’s all buttoned up with oil and coolant back in it but it’s snowing right now so I’ll wait until tomorrow to fire it up and check for leaks. I always forget how much of a pain it is to get the valve cover gasket back on it really makes me not look forward to the next valve job. I’m really looking into the crf300l rally as a next bike to commute on so I’ll be stuck with exactly the same engine to maintain but jokes on me because these are probably the easiest to work on out there. Doesn’t get simpler than a Honda single right?Yesterday I removed the GASKET from the left crankcase cover, it went really hard and slowly. An hour and a half of work maybe more. I edited the video and downloaded it to YouTube:
Ease of maintenance in old motorcycle is less related to the brand.Doesn’t get simpler than a Honda single right?