iainw
Cruisin' Guzzisti
I've skim read most of this and I think we're looking at three possible causes, fueling mixture, ignition or a cylinder head problem. I'll offer my thoughts on the mixture.
The picture of the spark plugs doesn't show what you should be looking for, you need to look inside them. You also want both plugs to look the same and have a coffee colour (not black coffee!), in theory you have two separate engines connected at the crank. They need to be doing equal amounts of work and if the carbs are set the same and one side is leaner than the other then the jets may be dirty. Needles and jets need to be in good condition, if a previous owner has mixed and matched used carb parts it'll never run right.
Tick over should be set in the usual way and use the lolly stick method to check both slides start to lift at exactly the same time.
To do a proper plug check you need to check the mixture at 4 different throttle openings. 1/4, 1/2, 3/4 and full. If you just go out for a ride and then pull the plugs the mixture you'll be looking at is from the throttle opening from last 30 secs or so of the ride, which is not a true picture of how it's running.
Mark your twist grip with a thin bit of white tape and put another piece on the switch gear next to it. Open the throttle to the stop and put another bit on the switchgear where it is now. With this full range being visible on the switch gear put 3 more markers at 1/4 1/2 and 3/4 throttle.
Get a long straight road, preferably on a slight rise, have the engine fully warmed up and run from a slowish speed in 4th gear for 30 seconds or so at the 1/4 throttle mark. Pull the clutch and kill the engine and bring it to a stop so that the engine hasn't run at any other throttle position. Pull the plugs and check their colour. Write notes from what you see.
Do the same again for 1/2, 3/4 and full throttle and you'll know whether the needles will need to be raised or dropped, if they end up on the bottom notch, fully raised and it's still lean, go up a size on the jets. Take care on the full throttle run, it can be a bit scarey, you may need to use top gear.
It's an awful lot of trial and error but the results are worthwhile and you'll know a lot more about your carbs.
All of this is of little cost but takes time and once your satisfied that the carbs are doing their job correctly then start looking to the other areas for a solution. BTW the plug condition can also indicate pre-ignition.
The picture of the spark plugs doesn't show what you should be looking for, you need to look inside them. You also want both plugs to look the same and have a coffee colour (not black coffee!), in theory you have two separate engines connected at the crank. They need to be doing equal amounts of work and if the carbs are set the same and one side is leaner than the other then the jets may be dirty. Needles and jets need to be in good condition, if a previous owner has mixed and matched used carb parts it'll never run right.
Tick over should be set in the usual way and use the lolly stick method to check both slides start to lift at exactly the same time.
To do a proper plug check you need to check the mixture at 4 different throttle openings. 1/4, 1/2, 3/4 and full. If you just go out for a ride and then pull the plugs the mixture you'll be looking at is from the throttle opening from last 30 secs or so of the ride, which is not a true picture of how it's running.
Mark your twist grip with a thin bit of white tape and put another piece on the switch gear next to it. Open the throttle to the stop and put another bit on the switchgear where it is now. With this full range being visible on the switch gear put 3 more markers at 1/4 1/2 and 3/4 throttle.
Get a long straight road, preferably on a slight rise, have the engine fully warmed up and run from a slowish speed in 4th gear for 30 seconds or so at the 1/4 throttle mark. Pull the clutch and kill the engine and bring it to a stop so that the engine hasn't run at any other throttle position. Pull the plugs and check their colour. Write notes from what you see.
Do the same again for 1/2, 3/4 and full throttle and you'll know whether the needles will need to be raised or dropped, if they end up on the bottom notch, fully raised and it's still lean, go up a size on the jets. Take care on the full throttle run, it can be a bit scarey, you may need to use top gear.
It's an awful lot of trial and error but the results are worthwhile and you'll know a lot more about your carbs.
All of this is of little cost but takes time and once your satisfied that the carbs are doing their job correctly then start looking to the other areas for a solution. BTW the plug condition can also indicate pre-ignition.