Does it flood out at all, if so maybe primer leaking through. The main jets maybe a little to large which will cause this problem for sure.
oxygen sensor
a diesel engine uses compression and has no need of spark plugs
old gas or fuel mixture needs adjusting
NGK number CR9E If your engine fouls plugs on a regular basis, the next step hotter plug, CR8E may help the plugs last longer.
NO, fuel is ignited by compression.
The stock compression ratio for a Suzuki QUV 620 is 10:3:1. Special spark plugs can increase that compression and the horsepower.
If your plugs are fouled, it means that they have a lot of carbon built up on the electrode. As gas burns in the cylinder, it leaves carbon that over time, builds up on the plugs. It's normal and nothing a good tuneup won't fix.
NGK BKR6E-11 are for the 4cyl mx6, they turn out to be the plugs for the ZE as well. These are colder than the DE plugs (NGK BKR5E), which is good in a higher compression engine. also, they are the correct length, where sometimes DE plugs can actually make contact with the piston (as it is taller and flat for high compression)
No, spark plugs do not cause ignition in diesels. The fuel compression causes ignition
diesel engines don't have spark plugs. they have very high compression cylinders that don't need the application of spark to fire, just compression of fuel and air.
Check fuel, try new spark plugs, check carbs.
you mixture on the carbs is way to lean you need to adjust them