Needle Circuit

[J_C]

Howdy howdy. I was running the 1100 yesterday around town. Despite the fact that plugs 1 and 2 still come out looking lean, the popping on idle & deceleration is largely gone. So I decided to take it out to celebrate my pilot circuit success.

I noticed that, what I suspect is the needle circuit, is running lean. Lots of popping when maintaining constant throttle, VERY surgy. (This doesn't happn while accelerating) Feels like when you're at the bottom of the gas tank trying to stumble to the gas station. The throttle is somewhere around 1/3 to 1/2 while this is going on.

(Oddly enough, to add fuel to the fire, this is at 5k rpm or so. WHEN I UPSHIFT, maintaining constant throttle, the rpms drop to 3krpm and POPPING/SURGING STOPS. I know rpms aren't suppose to play a factor in the needle circuit, but how else do you explain it? Anyway...)

So my dynajet needles, if memory serves correctly, are clipped at the 2nd notch from bottom. Ultimate question is: would y'all recommend shimming half a notch, or just dropping down to the first notch.


I know plug chops are ideal, but I live in LA. There aren't any backroads anywhere near here to chop the engine and pull over to pull the plugs.

[dardoonk]

What jets are you using now?

[Nessism]

I'd move a full notch since the symptoms you describe are fairly severe.

[J_C]

What jets are you using now?

Pilot - 47.5
Pilot Air - 170
Main - Dynojet #132

[J_C]

I'd move a full notch since the symptoms you describe are fairly severe.

Yeah that's kind of what I was thinking too, I just wasn't sure what kind of impact it would have... I'm worried about overheating they way it is now, though I don't know if that's a valid fear.

[chef1366]

Make sure your ignition advance moves freely and is free of rust and dirt.

[chef1366]

Also make sure they are all on the second notch. I've put it on the wrong notch before. The bottom notch seem pretty rich to me and some of the things you are describing seem ignition related.

[J_C]

My ignition what now? is that the thing under the right side cover you turn with the socket? If so, I checked the timing marks or whatever about 1.5 years ago (less than 60 miles ago)

[J_C]

Is this what I'm supposed to look at?

[Nessism]

Grab that rusted looking piece in the center, under that bolt with the 7 on it, and see if it turns. It should turn slightly as the rpm's increase (mechanical spark advance).

[chef1366]

First spray some brake cleaner on the advance to clean it. The deal with the springs. Then some kind of lubricant like Mr. Wrench.

[J_C]

OK thanks guys. I'll give that thing a turn on Friday when I get back from my business trip and let you know how it turns.

Bill, I assume to get to the spring and all that I'll need to get the three screws out and take off that top piece right? I'll need to get a right angle screwdriver; the case guard is in the way of the last screw.

[chef1366]

I wouldn't take off the ignition plate. Just do what I said and make sure it moves freely.
I bet it's just sticking and that's why your getting the popping.

[J_C]

Today I got into the ignition advance. I finally got the ignition plate off. It all looked good, turned relatively freely. HOWEVER. I did notice a slight resistance, around 1/3 to 1/2 way through its short range of motion. Almost felt like two parts were barely contacting for just a split second. It didn't stop it, but it did slow it.

I sprayed in carb cleaner and let it soak. I cleaned up the pieces I could access. The little hesitation or resistance was completely gone after the first spray. I allowed it to dry and then liberally sprayed in some wd40, ensuring it was able to get into all parts of the advance.

I am sincerely hoping that the point of resistance corresponds to around 4.5-6k rpm, and that the little amount there was lead to the stuttering/surging. I don't know how much force is used to turn the ignition advance in action; if it's a lot it probably won't be the issue. If it is just a little, as if it could be felt while turning it using just my thump and index finger, then we might have a winner. Test ride next week will determine!

Thanks for your help, Bill and everyone else

[chef1366]

My fingers are crossed.






And toes. :-D