Throttle Response Problem

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun May 05, 2019 8:39 am

Actually, could the carb be adjusted too lean?? Enough for a good idle, but when you roll on the throttle it's leaning out..?

Geoff Hastings · Post by **Geoff Hastings** » Sun May 05, 2019 9:57 am

It's possible the carb has been adjusted to compensate for an air leak, New o-rings would be the first thing to do, no point in trying to set up a carb if you have an air leak. Try spraying wd40 or similar around the carb flange at idle and see if you get a change in idle speed indicating a leak.

LOUD MOUSE · Post by **LOUD MOUSE** » Sun May 05, 2019 10:19 am

WD40 doesn't have PROPANE as a POWER SPRAY source any longer so unlike years back a vacuum leak won't Raise the RPM. ..............lm

Geoff Hastings wrote:It's possible the carb has been adjusted to compensate for an air leak, New o-rings would be the first thing to do, no point in trying to set up a carb if you have an air leak. Try spraying wd40 or similar around the carb flange at idle and see if you get a change in idle speed indicating a leak.

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun May 05, 2019 3:29 pm

What I meant by that is maybe I have the fuel screw in too far, so its starving for fuel - I don't think it has an air leak, it'd be all over the place as far as the idle goes, and it's not.

I haven't really had much of a chance to mess with it - or do much of anything else - since I got put on a day shift. I *Was working 3am to 11:00, which I loved; even though I got up early, I had my whole day to spend in the garage - now, not so much since I'm working 10 am to 6pm. And it sucks.

But anyway...I was thinking about WHY I had such a great idle, but under load it was nothing - and I thought the increased demand for fuel may have / might be the reason - maybe it's just not getting enough...? I just haven't had time to mess with it.

A baseline for the CA77 carb is what...? 1 1/4 turns out for both screws? That's where I started...is there any insight for 'tuning' those two screws...?

LOUD MOUSE · Post by **LOUD MOUSE** » Sun May 05, 2019 4:40 pm

<1 1/4 turns out for both screws? >
This is for the Air Screw only.
The Slide Screw is what ever it requires to have the engine idle correctly. .............lm

Dr. Frankenstein wrote:What I meant by that is maybe I have the fuel screw in too far, so its starving for fuel - I don't think it has an air leak, it'd be all over the place as far as the idle goes, and it's not.

I haven't really had much of a chance to mess with it - or do much of anything else - since I got put on a day shift. I *Was working 3am to 11:00, which I loved; even though I got up early, I had my whole day to spend in the garage - now, not so much since I'm working 10 am to 6pm. And it sucks.

But anyway...I was thinking about WHY I had such a great idle, but under load it was nothing - and I thought the increased demand for fuel may have / might be the reason - maybe it's just not getting enough...? I just haven't had time to mess with it.

A baseline for the CA77 carb is what...? 1 1/4 turns out for both screws? That's where I started...is there any insight for 'tuning' those two screws...?

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sat May 11, 2019 12:34 pm

"This is for the Air Screw only. The Slide Screw is what ever it requires to have the engine idle correctly."

Could you expound on that a little more, LM? They both work together to produce a good idle...what does 'correctly' mean? How do you get to 'correctly', especially for a machine with no tachometer...?

Geoff Hastings · Post by **Geoff Hastings** » Sat May 11, 2019 1:21 pm

The slide screw stops the slide from closing fully. Set the air screw 1 1/8 turns out. Then adjust the slide screw till the idle is how you want it.