lean or rich? between 5 and 7k rpm, when given full throttle, the engine gives little acceleration and creates and rythmic heavy shaking - is that a lean or rich condition? Currently carbs are at 40/150 jets, needles set to 2nd-lowest setting (=2 or 3 washers to those without adjustable needles). do I need to Adjust the needles higher to their last position or drop them down? thanks
I'd say you were running rich, especially with the jets and needle settings you describe. I've got a lunchbox and the stock exhaust (with holes drilled into the end thanks to a previous owner) and my 40/147.5 seems too rich. I'm actually gonna post up about my questions in a minute...
Is it actually "surging," as in accelerating harder for a moment (at least that's what I think of when i hear the word)? Or is it bogging down, as in losing power in that RPM range? I'm willing to bet that you mean it's bogging at those engine speeds, which is kinda what mine is doing at WFO, leading me to think I need smaller mains (thinking about dropping down to 140s) Anyway, are you holding the throttle wide open when this happens, or part way? As I understand it, all the way open is affected almost solely by your main jets, whereas partially open is more your needles.
In short, I think maybe you should try dropping the needles a notch, since it's the easiest thing to do, and see where that takes you. If it improves a bit, but you still have problems at WFO, maybe go down a bit on the main jets.
I'm sure someone with more experience and knowledge than I will come in and give you some more advice, but that's my two cents...
I had the same problem with full throttle going from 3k to 10k, at around 6k it surged.
I was running 137.5 with k&n drop in and pipe, went to 135, helped a bit, and on 132.5 it was gone. So stayed there.
So +1 on rich.
domas: thank you for input, but I'm riding a 95 so we're on completely different pages as far as carburators - yours has 3 jets, mine has 2.
Badguy: I'm thinkin it maybe rich as well - check my floats and the fuel level is about 2-3mm higher than the fuel bowl gasket at its highest point, that would richen things up a bit, and if I have been moving the needles the wrong way - even worse!!!!
Yes it is BOGGING between 5-7k RPM as in barely accelrates and shakes hard - also almost bogs out just off idle.
will be adjusting the floats tomorrow hopefully, guess I have to play "which way do I bend this flange" until something changes!
Another weird observation - with the lunchbox air filter off and the bike idling... it spits a mist of fuel OUT of the carb intake towards the rear of the bike when I open the throttle - wtf is THAT?!
Too rich.
Do a plug chop @ the rpm range to see