Idle question

Now that I have synch'd the carbs using the low tech method described here , the bike is running a whole lot smoother. It was so out of whack, the initial go sucked everything over to the left side. Took a while, but it helped a lot. I also found I had a hole in the tube the goes between the carbs, so I replaced that. Even better idle & running. Now I have a nagging little issue. Here is the scenario:

Start the bike cold, "choke" on. Fires up 1-2 kicks, revs about 3K.
Let off the choke a bit, brings the idle down to about 1500-2K. I ride at this point.
Once it warms up good (10-15 minutes), I can shut the choke down completely, and have it idle about 1500. Once it runs for about an hour, I can take the idle down to about 1K (Yea, I carry a small screwdriver in my pocket!).

Here is what bugs me - the FSM says it should idle at 900-1100, but if I set it that low, it idles so low at first I have to blip it to keep it going at lights. It also seems to stutter every minute or so.

What I do is keep it set at about 1500 idle speed when good and hot, which makes it run about 1K initially, as the idle speed will slowly increase as it gets hotter. Is this typical of an aged carburetted bike, or should I be looking for another gremlin?

Keep reading your FSM... most of them have a blurb about cautioning you to use an external tach to set the idle since the stock tach is very inaccurate at lower rpms.

Your bike is taking too long to warm. This means that your pilot circuit gas passageways or pilot jets are obstructed a bit I would guess or your choke gas pick up isn't flowing gas as it should.

Thanks WG. I poked around briefly looking for tachs, but I am hung up on a (probably) small detail. The stock tach is mechanical - how would one hook up an external one?

I agree *something* is up in the pilot circuit, and I appreciate your info. Over the winter I soaked / cleaned / blew out everything I could on the carbs - had them taken down completely (still surprises me that they work at all!). Perhaps I need to give 'em another go, or hire someone

How do you clean the choke circuits? I'm pretty sure that's my idle problem as well.. except mine's kinda wierd because my bike will idle around 3K, then I toss the choke on full and let it rev up with the extra gas until the revs start to drop again due to too much gas, at which point the idle settles down completely to where I've set it..around 1200-1500ish, a nice steady idle.

The wierd thing is that it then starts to creep back up when I'm sitting there, until it's hitting around 2500rpm, or higher.. depending on how long I have to sit at the light. I don't do this too often, but if it's running really high, I do it to calm it down. Half choke does nothing but kill the bike.. it's kinda annoying.

Nevermind.. I think I figured it out.

My float levels must be off! When I crank open the choke, it sucks more of the gas out of the float bowls, which brings the levels down. Once I turn off the choke, the bowls fill faster, since the bike is using less gas, and they over fill, creating a rich condition and raising the idle slowly.

Does that sound right? :huh:

:laugh: