Plug colours different

[dpb]

Hello, did 200 miles yesterday. This morning plugs 3 & 4, are sooty, 1&2 are dark toast, no soot. I'll have a go at tuning again.  Any other thoughts? 

Cheers 

Dave

[keith1948]

Hello Dave

I recently replaced floats and O rings in my Strombergs. To do this the jet assembly has to be unscrewed. I reset the float heights on the new stay up floats. To get the carbs approximately set up I screwed in the jet assemblies the same on each carb (3 turns from memory) and then marked them with a marker pen as a datum point. First journey plugs were sooty so I screwed up the jets one flat. Second journey less sooty so screwed up another flat. Eventually after a few minor adjustments all plugs are now dark toast. I guess I could go a bit leaner.

I also checked inlet airflow using a carbalancer. The hissing sound on each carb was the same. Lifting the piston a fraction on each resulted in no change in revs so that was ok.

In your case sounds like the rear carb is running rich so weaken the mixture on that carb. Also make sure that when the throttle lever moves that both carbs move together. If not then loosen the linkage and adjust throttles and retighten the linkage. If the front carb opens before the rear then that won't help. Both should open and close in unison.

Keith