82 GS650L Idle adjustment knob...?

[Guest]

I feel really dumb, but I have a question about the idle adjustment knob on my 82 GS650L.

The other day I put new carb boots on my bike and I must have upset the carb balance during that process (or maybe the new boots just aren't breathing as much as the old ones did), because I started to get too low of an idle. After warm it was idling under 1000 rpm and kept stalling out on me. So, I thought I would just adjust the idle knob. The manual states to start by screwing it all the way in, then backing it out 2 turns as a starting point. Mine just doesn't do that... basically, it was already almost all the way backed out. I got a hair more out of it which seems to have helped the idle, but what was also weird is that when I tried turning it in, it barely moved. I got maybe a quarter turn out of it and there was a weird flicking / fluttering noise coming from the engine when I did that. Didn't seem right.

So essentially it feels like there is no room to adjust.

This is what I was trying to turn:

20190905_174723.jpg

That is the idle adjustment screw right? I feel so dumb right now but something doesn't seem right.

[Rich82GS750TZ]

NOOOOOOOO! Don't turn that. that has nothing to do with your carbs. That is the automatic cam chain tensioner, and it should never be turned when the bike is running. the idle mix screw is on the back bottom side of the carb bank. I'll try to find a pic.

[exzachtly1]

OK... so yeah confirmed I'm dumb. Thanks

I looked all over the carbs and I don't see anything, maybe I'm just blind. Gonna go take another look now...

[Rich82GS750TZ]

These may not look exactly like your carbs but its the knob at the bottom center in the middle of your carb bank that is your idle adjustment screw.

[exzachtly1]

Yes! Thank you, I see it now. It is in the same place as pictured. So another dumb question, how the hell are you supposed to turn that when the engine is warm? My hand barely fits there as it is... long pair of pliers or something?

I'm thoroughly embarrassed but that's why I love having these forums.

[Rich82GS750TZ]

Ahh, yes. just get a longish flat head screw driver and put the flat if it in to engage in knob head and tap on it from the side so as to turn the knob to the right to tighten it or to the left to loosen it. With the engine running, you'll hear the idle go up or down depending on if you're turning the knob tighter or looser. Get it settled somewhere north of 1000 RPM or so and you're good to go. At least that's where my idle seems happiest.

You really should have a owners manual and a service manual for your bike. You can download both at the bikecliff's link under my signature.

You're welcome. And you're not dumb. I'm sure you're not the first to do this and won't be the last. We're all here to help each other keep these great classic bikes on the road. Hopefully you weren't too forceful on the cam chain tensioner as to cause any damage.

Create a signature with your bike year and model in it. Then you'll never have to remember to include that info in any post. Also, we like pictures. Good luck.

[exzachtly1]

Cheers. Yep I do have both manuals already, I've done a decent amount of work on this bike but never dug in to the engine aside from doing valve clearances. I actually used to have an account on here, years ago, but it expired and I only recently joined back up because I took a renewed interest in the old gal.

I remember this knob now that I'm messing with it haha. It's just been years since I really touched anything on the bike so I guess it was just brain fart / blonde moment.

I did not turn the tensioner knob much at all. It was pretty apparent quickly that "this is probably not the right knob"

Now I can't get the bike to start though not sure what's up. All I did was take the carbs off and install new intake boots.

Side note, the idle knob for some reason is very wobbly. There's a lot of play in it, so tapping with a screwdriver isn't really working. Best I've found is to use a 15mm wrench to grab it and turn it. Is that normal or should I be taking the carbs off to see what's up?

[Rich82GS750TZ]

As I recall (it's been a while since I've had my carbs off) the Idle screw has a spring on the back side of the plate which keeps a fair amount of tension on it; enough to not let it adjust by itself, but not too much that you can't turn it my hand, screwdriver, or wrench when you need to. If yours seems "wobbly", maybe the spring has sprung or something else may be amiss. Turn your petcock to "prime", only for a minute, than back to "on" to make sure you have fuel in the bowls. Turn your idle screw all the way in then back out 2 full turns and see if you get fire. then you'll know if your idle is too high of too low. in playing with it you may have it turned too far in (or out, I forget) to run to start it.

[Redman]

Yah, probably need to adjust that after replaceing the carb boots and orings, because air leak there will raise the idle, easpecailly after the engine warms up.

Good that you found the idle adjustment. It is really just a stop that sets how far closed the buttterflys can go, kinda like it holding the throttle so far open for you.

I try it adjust it when engine warms up, but just before is too hot to get hand in there.

.........
Side note, the idle knob for some reason is very wobbly. ....

Hum... is suppose to be held by a bracket that is held in place with a screw of the carb bowls. Maybe that was missed on a reassembly.

[Mr.humbucker]

With a good leather glove on that is not too thick I am able to reach in and adjust it when the bike is running and the engine is warm/hot. I have had a few wrist burns when it didn't go so well ... all part of the learning curve. If it is wobbly it maybe that the nylon/plastic grommet/housing thing ... on the bracket is missing.

[exzachtly1]

All sorted now. Got the bike started and got the idle adjusted correctly. It just needed a little priming after all... I guess it was just one of those days

Funny thing is I did prime it for about 20 minutes and it wouldn't start. Let it sit for a couple hours and it started right up. Go figure.

[Rob S.]

Remember the game "Operation"? A steady hand or you get buzzed. Of course the thing is, to get it correct, the bike has to be completely warmed up. I've been known to stick my left hand in there while sitting on it at a red light - BUZZ!

Even when I'm crouching beside it, and my hand is as steady as it gets, I frequently set off the buzz. Remember what Keanu Reeves said in "The Replacements" - "Chicks dig scars."

As one of our members would say, "Cowboyup" and get in there!

[exzachtly1]

Remember the game "Operation"? A steady hand or you get buzzed. Of course the thing is, to get it correct, the bike has to be completely warmed up. I've been known to stick my left hand in there while sitting on it at a red light - BUZZ!

Even when I'm crouching beside it, and my hand is as steady as it gets, I frequently set off the buzz. Remember what Keanu Reeves said in "The Replacements" - "Chicks dig scars."

As one of our members would say, "Cowboyup" and get in there!

Lol, thanks Rob. I did make sure to fine tune it after a nice 30 minute ride!