Hello all,
ive got a new to me 2018 Montesa 4rt with a backfiring problem.
it tends to only backfire (or after fire) when I’m holding revs at a higher rpm than idle.
It tends to continuously foul plugs as well. I’ve gone through 3 plugs so far and after every warm up, it’ll foul a plug. The plug also slightly smells of gas.
It starts 2nd kick when cold, but starts 1st kick when warm.
things I’ve checked so far:
1. Cleaned air filter and removed excess oil
2. new spark plug (cr 6)
3. Valve clearances set per manual
4. resealed and tightened exhaust connections
5. new fuel (93 octane non ethanol)
Other things I’ve thought but haven’t tried:
new coil
different gas with 10% ethanol
hotter plug (it’s 30 degrees f recently)
could anyone guide me in the right direction? Not sure if the idling sounds right either…