AJS & Matchless Owners Club

Could someone explain what IT BOGS MEANS

It means it feels like driving in deep mud.

Engine performance is a combination of correct AFR ( Carb setting ) and timing , if either are incorrect the engine will not operate at optimum performance . The manufacture will have determined the best compromise and should be used as the starting point
On a unknown engine, the first check would be to confirm that you have reasonable compression ( resistance to kicking over is a good check )
Then check that the carb is set to manufacturers settings and any filters are clean in the fuel system , before checking static timing at TDC compression
Auto advance mechanisms are prone to sticking if worn and chain is too tight !

The following diagram shows the theoretical effect of incorrect timing and mixture
When tuning an engine the process at every throttle / load setting would be to set the mixture , then find MBT ignition setting and repeat the process getting closer to optimum AFR and timing at each point . The compromise in later years was to worry about emissions , but luckily we don't have to worry about that

willowbedone wrote: ↑Wed Aug 24, 2022 9:37 pm Could someone explain what IT BOGS MEANS

Some bikes suffer with an issue where it will fly up to a given rpm/speed then it feels like you have driven into a bog where the bike just fails to carry on with the power but its all of a sudden and not where you would expect it. Just a bit like when you run out of fuel.

your symptom Jackstringer sounds like sticky auto advance or bob weights , where the timing changes rapidly

g80csp11 wrote: ↑Thu Aug 25, 2022 2:33 pm your symptom Jackstringer sounds like sticky auto advance or bob weights , where the timing changes rapidly

I have a G3 that sings and spends most of it's time getting annoyed by modern cars that cant seem to reach the speed limit. I was just explaining how bogging feels, I have only had that issue with bikes with 2 stage carbs and one isnt feeling too well.