BigBob wrote:I remember checking float heights back in the dark ages not too long after I got a Big even though it was running perfectly, and they appeared to be miles out according to the Holy Book. Along the lines of "if it ain`t broke..." I didn`t touch them and it right just fine for decades after that.
On every other set of Big carbs I`ve checked (plenty) the float heights were way out according to the Bible but were running fine so I`ve not touched them.
It`s a black art for sure.
As for the airbox rubber.... I put mine in a pot of boiling water for a couple of minutes and it becomes incredibly soft. I can usually fit it within 30 seconds with one hand.
Make sure the air filter is removed first to help with access. Removing the battery box mounting bolts gives you another centimetre of play as well
Yeah perhaps i should have left well enough alone with the float heights.
Heres the craic and maybe ye can shed some light.
Got her started on the bench this evening. The good news is Dave seems to have played a blinder and engine sounds good

Total legend and your beers on me mate.
Bad news is she is blowing black smoke. Gases at exhaust tip are way too hot. Sounds poppy and will die unless i hold it above idle. Loadsa soot in the exhaust.
My hope was it was just the shot of oil i bunged down the bore post Daves rebuild (yrs ago) that was burning off but shes still blowing black a touch.
Things i did carb wise was replace a wrecked needle when i bent it. The replacement was a1 but im going to check i got the spring seat installef in the correct order.
I dicked with float heights. Thought i got em right but as Bob says kind of a dark art. Will wet test tomo to see heights definitively.
I changed the float bowls to the later dr big ones with overflows.
I also changed the seals on the float frames. The new ones were a firm push fit.
Can i rule out a timing issue? My guess is yes as Dave is on the ball but is it even likely? I only ask as the exhaust gas temp is mad.
I'll change the plugs in case they are fouled from the oil i dropped down the bore.
So what does the hive mind reckon?

Open to any and all advice
