Foul Spark Plugs

K

koolerthantim

New member
Hi All, i have an 84 MHR mille, i brought it new, its always been a fantastic bike, never let me down. its been in the garage for the last 10 yrs. i recently did it all up, re powder coated the triple tree, front shocks, wheels etc, it looks great. the problem i am having, is the front cylinder does not operate all the time, very intermitant. when this has happened, i have taken the plug out and it is all sooted up, i clean and put back in and ti trys to fire. i have been told it is the additives that is put into the fuel, also been told to go from a BP7HS spark plug to a BP5HS. can anyone please give some advise?? Tim Mille
 
Are you saying it's been parked for 10 years? It sounds like a carburetion problem to me. Did you pull the carbs and overhaul them before you started it?
 
Yes the carbies were stripped and cleaned, we even fitted new petrol shut off taps. Now instead of one shut off tap, and the fuel fed to the front carbie from the main tap on LHS we have another tap on the RHS. i am sure the fuel is getting to the carbie
 
The bike has been in a mechanics shop for a couple of weeks, the mechanic specialises in pre 90 Dukes, it has him stumped. he had the carbies completely apart. he is the guy that said i should be running hotter plugs, due to the petrol additives.
 
One thing is to check that the carbies have one of the aftermarket jet kits installed. I worked on a monster that had one and it was flowing enough fuel to run a Kenworth. This poor thing was drowning. I replaced the huge main jets and lowered the needles and it's almost back to normal.

Another thing to check is if it has the black plastic floats. These can become fuel soaked allowing the flooding.

Start lowering the needle in the front carb to see if it leans out a bit.
 
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