I ran a Czech made JAWA 350 sidecar outfit for 3 years and 10,000 miles with a disintergrating right hand journal bearing. The engine ran to 75 MPH still with no vibes, started OK and ran smoothly.
In the end the engine ran but refused to move the bike so I had to replace it. It took just under an hour to put in a new journal bearing and seal in the drive. The original had only 3 out of 8 balls and no cages left!!
Probally explains why the bike is still made and sold to millitary and civilians all over the planet. At present there are an etimated 7 million in existance trundling around in the world. It is the world's most common 2 stroke bike.
I also ran mine on neat diesel for a month during the 2000 petrol crisis and it still ran the same as on gasoline. They'll also run on Methylated Sprits, Cooking Oil, whatever goes bang good when compressed to 11:1.
Out of the 15 bikes I own and others I've owned in the past, this one is the least hastle, mechanically, to run and work on.
My worst bike is a Suzuki, which just seems to self destruct as quick as I can fix it.
Now why can't all vehicles be designed by people who know that some guy may need to perform major surgery on the engine, etc. later in the vehicles service life, at home in the garage or drive??
On the lawnmower, try using anything other than an NGK plug and you should find it'll start easier. I run LODGE Sintox race plugs in every engine I use. Reasuringly expensive but reliable. They last about a decade before you need to think about changing them, instead of the 3 or 4 months of NGK plugs.
KLG plugs work well in chainsaws too.
Always drain out the gas tank on lawnmowers when not planning to use them for a month or two as unleaded gasoline loses potency very quickly and will leave like a fish paste residue in the fuel system.
All the stood up bike I'm asked to wave a magice spanner over have fuel residue prolems.