ATV Carb Help, please!

Joined
Nov 16, 2017
Messages
8,311
Location
Central Oregon
Yup! This is what I've concluded also - too lean mixture, either from too much air or too little fuel. I'm not sure how to identify which one it is. When I get home tomorrow night, I'll install the new boots and O-rings, as well as rig a direct-feed bottle for fuel to the carb. I'll report back. I appreciate all the input.
Spray starting fluid around the boot.
 
OP
TheCougar

TheCougar

WKR
Joined
Jun 6, 2016
Messages
3,242
Location
Virginia
Spray starting fluid around the boot.
I have done that, and around all the carb connections, and around the gasket connections... basically every place that an air leak might happen. No luck so far. Keep the suggestions coming! I'll install the new boots in case there is a leak that I haven't found. I'll report back tomorrow night.
 

Wrench

WKR
Joined
Aug 23, 2018
Messages
5,926
Location
WA
Grab a propane torch don't light it, but flow fuel through it. Go around the carb boot....then in the intake. If it changes idle on the boot....voila. if it changes in the intake, pull the carb, drop the bowl (those are NOT #2 philips. A #3 will work). You have a plugged pilot jet. Pull it, clean it and rock on.
 
OP
TheCougar

TheCougar

WKR
Joined
Jun 6, 2016
Messages
3,242
Location
Virginia
there’s a part in both carb rebuild kits that I haven’t identified nor seen during my carb teardowns. That’s the only thing I haven’t replaced yet. Both intake boots are replaced, fuel lines and filters cleaned and checked, all the jets have been replaced, new spark plug, new air filter, etc. I’be for two carbs that act up and the OEM carb is on its second rebuild kit. I’m running out of ideas at this point. I’ll tinker with it today and report back. This is the part I can’t identify. It’s hard to see, but there is a very fine mesh filter on it. Looking at the carb diagram, it may be a part hidden inside the carb beneath one of the jets.
 

Attachments

  • D2DE38C3-00A6-415A-A44B-8AE7873F9D16.jpeg
    D2DE38C3-00A6-415A-A44B-8AE7873F9D16.jpeg
    68.2 KB · Views: 20

cnelk

WKR
Joined
Mar 1, 2012
Messages
7,083
Location
Colorado
If my memory serves me correctly on these Mikuni carbs, that's the intake screen below the seat or the seat itself
 

cnelk

WKR
Joined
Mar 1, 2012
Messages
7,083
Location
Colorado
Watch this video - especially between the 05:00 - 06:00 minute marks. Its the same carb



 
OP
TheCougar

TheCougar

WKR
Joined
Jun 6, 2016
Messages
3,242
Location
Virginia
Okay, so update: the quad is running back to normal now. Today I rebuilt the OEM carb… again, but this time. I swapped jets and put the larger ported jet on the main since I was bogging down at full throttle. That appears to have fixed it. I still need to tweak the fuel/air screw a little, but she runs great at full tilt now. There is still some hunting at idle, but it runs and I’m headed in the right direction. Thanks to everyone who gave advice!
 
OP
TheCougar

TheCougar

WKR
Joined
Jun 6, 2016
Messages
3,242
Location
Virginia
Are there any approved techniques for adjusting your idle screw and your fuel/air mixture screw? Where should your idle screw be when adjusting your fuel/air screw? Right now it idles perfectly when warm and choke off. When cold and choke on, the rpm is too low and I need to feed it throttle to keep it from dying until it warms up a bit. Once warm, if I put the choke on, the motor dies.
 

Marble

WKR
Joined
May 29, 2019
Messages
3,403
I would put a new oil and filter in just in case too much fuel went to the cylinder and made it way into the oil. Happened on mine a couple times.

Sent from my SM-G986U using Tapatalk
 
Top