Popping Exhaust

[Guest]

As i wanted to keep the standard look of the exhaust on my gs1000g I opted to adapt the downpipes and fit non standard megaphone type exhaust which look like the originals.At first they seemed fine but the bike was hard to start from cold,valves adjusted now starts fine from cold but get popping in exhaust and revs hang up slightly.I took out the rockwool which was wrapped round baffles and packed with wire wool, this has helped but still popping a bit,carbs are all standard and spotless internally,have set screws on top of carb inlets to engine intakes about 1 1/2 turns out,plugs grey in colour after plug chop,air filter standard and lightly oiled,carbs balanced....i hear on forum about raising needle to try and help this symptom, how do you do this in detail ,or do grey plugs mean i am running a bit weak?if so how do i adjust..or is alll this just hit and miss trying to get round my non standard exhaust,,,,,any advice gladly accepted,Cheers.........

[Steve]

The popping in the exhaust is telling you the mixture is lean, but it could be lean from carb mixture or an exhaust gasket leak.

Before you raise the needles, try turning the mixture screws out another half a turn. When the engine is fully warmed up, tweak the screws a bit further, listening for the highest engine rpm. Reset the master idle screw if necessary, then do the next carb and so on, until you are done.


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[trippivot]

lean misfire richen it up

FIRST idle drop test the mixture screws to get the highest idle per cylinder and readjust the idle speed screw after all 4 mix screws are readjusted.

having the exact same mixture setting on all 4 cylinders is not always the best.

then if the problem still exists
you need to decide if the pilot size needs to be increased or is the idle fine after you changed the mixture screws. and the needle needs to be lifted.

trial and error is tedious until you get the experience to know what is needed.

[PAULJAC47]

How To Ajust Needles

I have taken out one of my needles and notice that the e clip is located in the fourth groove down from the top(there are five grooves)if i put clip in position three does that means i am enriching mix? or does it weaken mix.Is position one at the top the richest position and position five at bottom the weakest? Many Thanks for any help on this guys.....

[80-81, GS 1100]

The higher the needle sits after your done
adjusting it the richer it is.
So I would guess if the clip is on the
lowest notch, the needle would sit higher
and the bike would run richer...
Look at the needle as a stopper that
is keeping the engine from sucking in more
gas. If the needle sits farther down in the hole,
less gas gets sucked into the engine.

[80-81, GS 1100]

Another thing to look at, when adjusting your carbs
is this:
You can get the idle correct and midrange correct
by adjusting the pilot and needle jets.
Where it gets dangerous is the main jet.
Back in the 80's I paid a mechanic to rejet a KZ1000
with smoothbores, and everything was fine except the
main jet. I ended up blowing a hole in a piston at
100mph because I probably had a too small main jet.

[Steve]

I have taken out one of my needles and notice that the e clip is located in the fourth groove down from the top(there are five grooves)if i put clip in position three does that means i am enriching mix? or does it weaken mix.Is position one at the top the richest position and position five at bottom the weakest? Many Thanks for any help on this guys.....

The clip is what determines the height of the needle when it is mounted. By moving the clip down, you will raise the needle, richening the mixture. The stock location is the third notch, so yours are already richened by one notch.


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[chef1366]

You are already at the rich end of the needle settings. You only have one more step. I would try richening the idle mixture screw. Also did you use new exhaust gaskets on the headers?