DrunkenDwarf wrote on 07/28/10 at 16:54:08:



when carb does not respond as it should dispite jet changes = blockages inside passages

it still gets hot enough to burn all deposits off, so I'd say your main is a tad lean (not knowing how long you spend at full speed) and your idle/choke is rich.

verslagen1 wrote on 07/28/10 at 17:27:51:

Which is why I went down a size on the pilot.

I don't spend much time at full throttle. I hit 80 in forth gear a day or two ago, but I generally ride in the 40-60 mph range.

I really should grow a set and do a WOT plug chop.  

Serowbot wrote on 07/28/10 at 17:28:09:

I'm trying to reduce the pops when I shift. It's pretty consistent.

The really weird thing is when the engine is warming up and I still have the choke out, it never pops on a shift. But as soon as I put the choke in, even if the engine isn't warm, pop!

Edited:


-D. Dwarf

Serowbot wrote on 07/28/10 at 20:14:01:

I've noticed no correlation between weather and backfiring. It could be because of my proximity to Lake Ontario, it's always humid.

Serowbot wrote on 07/28/10 at 20:14:01:

I've tried this several times last summer, with jets 145, 150, 152.5 and 155. I'll see if I can find my posts from that time period and link to them.

I've never noticed any change when backing off the throttle.
I don't know if I'm doing it wrong (not waiting long enough, waiting too long, backing off to far, not backing off far enough, whatever) or if there's no response or if I'm incompetent.

-D. Dwarf

ralfyguy wrote on 07/29/10 at 08:34:58:

...sounds like you got a leaky petcock diaphragm....

ralfyguy wrote on 07/29/10 at 08:34:58:

I'll try to remember to do that tonight.
I've got a spring around the vacuum hose, so we'll see how well I'm able to pinch it off.

-D. Dwarf

It is not said that both of our petcock diaphragms are bad. Maybe this is just the way it is. BTW mine is a '06 S40 with 12,500 miles on it. I was thinking about getting a new petcock, because the lever only turns with brutal force. I disassembled it last weekend, cleaned what wasn't really dirty, lubed everything that moves on it and put it back together with no real improvement. I didn't notice any gas or gas smell either with the hose off. One of these days the lever is gonna break off. Are they all turning that hard? It worsens significantly when the temperature rises above 90F. In the morning around 70F it isn't that bad. Does yours turn that hard?

Oh and for the record: My pilot jet is a stock 52.5 without bleed holes. And the pilot screw is 2 1/4 turns out. This seems to be the sweet spot on mine. I tried more and less and it wasn't quiet right. I always come back to 2 1/4 turns out. However in winter I set it to 2 1/2 turns, as it then runs as smooth as in summer.

Where did you get the 52.5 pilot WITH bleed holes from? Does that mean it may run a bit richer than the same size without holes? I wish I had one to try, as the 55 jet I have is too much.