Issues with Idle and Mixture Screw

The54Kart

New member
So I'm using a PZ22 carb, got the jet needle clip in the middle groove, float height at .860". Nothing crazy or experimental going on here, but for some reason my kart won't idle properly until the mixture screw is 1 3/4 turns out, and I get the highest RPM at 2 1/4 turns out. And not only is that way far off from where most other drivers are, but my engine also seems to hesitate really bad every time I start it up. Cold or warm, it'll idle really low (1100 to 1300) for up to 15 seconds before the RPMs go to their intended range (1800-2000).

Really not sure where the issue lies, the weather isn't crazy (usually 85F - 90F, humidity 50% - 60%), and my setup isn't exactly experimental. I was wondering if it was an issue that my fuel pump vent was covered by some synthetic gel (suggested by a friend), but I was promptly told it was a non-issue.

Any advice? I'm so lost lol
 

OldsSS1

Member
As it turns out, I recently had same type of issue. Ended up resetting idle mixture screw(which is an air not fuel adjustment) down to 3/4 turn off of seat and idle speed a little above 2000 RPM and problem solved. Starts much easier too. If you read L206 Carb Settings thread at top of this category, recommended setting to start at is 1 TOS. This lower TOS setting will give you a much richer setting and should eliminate off idle stumbling when accelerating. Hope this helps!
 

The54Kart

New member
As it turns out, I recently had same type of issue. Ended up resetting idle mixture screw(which is an air not fuel adjustment) down to 3/4 turn off of seat and idle speed a little above 2000 RPM and problem solved. Starts much easier too. If you read L206 Carb Settings thread at top of this category, recommended setting to start at is 1 TOS. This lower TOS setting will give you a much richer setting and should eliminate off idle stumbling when accelerating. Hope this helps!
Well that's the problem, if I set the mixture screw that rich the engine won't stay running. It'd be simple if my setup was otherwise rich, because then it'd be as simple as moving the jet needle clip or adjusting float height, but neither of those adjustments have made a large impact in where I can set the screw. It seems if I want to get to 1 TOS, I'd have to bring the needle clip to the top groove and lean out my float, and even then I'm not sure.
 

OldsSS1

Member
Are you sure the idle pilot jet has not been altered(opened up to larger size) as that would be my next check? If you have an extra pilot jet available, I would suggest swapping it out.
 

The54Kart

New member
I guess it's possible, at least worth a check. I can't imagine how it could've been altered, but the size of my jets was something I haven't ever payed much mind to.
 
So I'm using a PZ22 carb, got the jet needle clip in the middle groove, float height at .860". Nothing crazy or experimental going on here, but for some reason my kart won't idle properly until the mixture screw is 1 3/4 turns out, and I get the highest RPM at 2 1/4 turns out. And not only is that way far off from where most other drivers are, but my engine also seems to hesitate really bad every time I start it up. Cold or warm, it'll idle really low (1100 to 1300) for up to 15 seconds before the RPMs go to their intended range (1800-2000).

Really not sure where the issue lies, the weather isn't crazy (usually 85F - 90F, humidity 50% - 60%), and my setup isn't exactly experimental. I was wondering if it was an issue that my fuel pump vent was covered by some synthetic gel (suggested by a friend), but I 300 t00was promptly told it was a non-issue.

Any advice? I'm so lost lol
Might have dirty jets. Bump your.Idle up to 2300 + actually adjust your idle right before you race , Set to highest rpm at your chosen idle . I've on occasion cranked my idle up to 5000 on the stand and re set idle to match the current weather . If you think about it your engine spends most of it's time between 4800 to 5800 during the race. NOTE OF CAUTION . Not real safe , And track rules may not allow this . Always have a helper .
 

Gab507

Member
Is this an early Walbro or the Chinese Briggs version? The two require different settings to run well. I believe the one tirn was for the newer Briggs carbs not the walbro.
 
Might have dirty jets. Bump your.Idle up to 2300 + actually adjust your idle right before you race , Set to highest rpm at your chosen idle . I've on occasion cranked my idle up to 5000 on the stand and re set idle to match the current weather . If you think about it your engine spends most of it's time between 4800 to 5800 during the race. NOTE OF CAUTION . Not real safe , And track rules may not allow this . Always have a helper .
Oops I was in error. I said adjust your idle I ment to say your air fuel mix at chosen idle.sorry l PM
 
Where is the post concerning setting the idle?
Fyi. I turn the idle up to aprox 5000 rpm + or- a bit on the stand then set the air fuel mix screw to max rpm a viewed on your tach. Re set the idle screw to desired rpm . With your carb now tuned for racing engine Rpm
 
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