gremlin

[young nip]

hi guys and gals. I have a queation cause Im stumped. Great site by the way. I have an 1100 f. I changed the old exhaust to dunstalls theis year. problem is I have a surge between 3800 and 4800 rpm.,quite noticeabl 1st to 3rd.Below/ abovethose rpms that bike works great. ( yank your elbow sockets)Began even before the pipe change. Im missing something. I adjusted my jets to richer and then went leaner .Same result.ive checked igniton, coils ,Wires and connectors, tried different gap settings.new plug caps.wires.The 4 plugs read the same colour. I even checked valve clearances , theyre right on mid clearance. air filter is new.Petocks no gas or air leaks. Vacumn seems strong. I checked boots( 5years old) when carbs were off, could not detect any cracking thru.replaced all the hoses. carefully cleaned carbs and components and everything was in really good conditon.syncro is righton,but surge remains.Idles perfect with excellent throttle response.when I use my vacumn advance the surge becomes worse.bike doesnt cut out like ignition problem, pops and stutters like its lean. Im using premium gas. could the problem be a vacumn leak ive missed. or a wire Ive thats fooled me.Ive checked wiring hot and cold. could the vaumn advance diaphram be done. ( seems to hold a negative pressure)could it be over advancing. Could it be a port in my carbs. a problem with my advance mechanism??what what what????
ILL take all ther help I can get.
Thanks
Steve

[Ken Talbot]

I see in your ignition note that you have some spliced pick-up coil wires. Might be worth a look to see if the solder joiint is still clean, and hasn't introduced some new flexing damage to the original wire next to the splice....

[TopCatGr58]

Hey Ken, and Young Nip,

He states that when he uses( I'm assuming he has it connected to vacuum vs. plugged) the vacuum advance, that the surge worsens. Like you eluded, the pickup wires are probably suspect, but also the advance unit itself....is it spinning/turning freely, not hanging up?? And doesn't this model year have mechanical advance parts as well, which might also be sticking??

He also mentioned new pipes, which probably means he is breathing better, and leaner, he stated he tried richer jets, but which ones did he have first, and how rich....how many steps?? The guide suggests 2 steps for 4-1 pipes. What are DUNSTALLS exhausts?? typo??

But along with trying the richer jets, don't these carbs have an adjustment to the vacuum slide needle that he could tweek? Does it sound like a poor transition from pilots to mains that is happening, or is it already too high of RPMS's and he should already be well into the mains?? Just some thoughts. T.C.

[skids]

It seems if if the diaphragm slide(s) are sticky or the needles might be cruddy. I had a set of JC WHipme mufflers that I could never compensate for with carb adjustments. If your exhaust system is a glass pack without a good steel baffle, you might be experiencing the same kind of problems that I had.