All Things Moto! Dirtbike Forums

Go Back   All Things Moto! Dirtbike Forums > Dirt Bike - ATV - Suspension Forums > 2-Stroke Dirt Bike Forums > 2-Stroke Dirt Bikes - Yamaha

LinkBack Thread Tools
Old 09-26-2018, 05:08 PM
Welcome To ATM
Join Date: Sep 2018
Last Online: 09-27-2018 06:25 AM
Location: Pa
Posts: 2
Default Please help. YZ85


Hi guys. Hopefully somebody can shed some light as i'm about to lose my mind. Ill give as much info as I can.

Problem: When I goose the throttle as quickly as I can from idle she bogs and shuts off. Likewise, if I put it in a underpowered situation, for example, 3rd gear just barely moving and I goose the throttle wide open as quickly as I can it bogs and shuts off. The bog im referring too would resemble somebody holding in the kill switch. This bog only occurs at and above 3/4 throttle.

I have tried many things to correct this issue which I will list. The only things that eliminate the bog are: 1. I turn the air mixture screw all the way in. 2. I ride with the choke on. 3. Set floats so high that gas pours from overflow. All of these cause the bike to run terribly rich but the bog disappears.

Note: If I ride the bike "normally" she runs perfect. No bogging, no sputtering. I weigh 200lbs and she will lift the wheel off the ground in 4th gear when the power band kicks in.

2003 yz85
Aftermarket parts include FMF Pipe, Boyesen rad cage with carbon fiber reeds and flywheel weight.

For starters, the pilot is stock size 45. Best idle seems to be in and around 2 turns out.
Needle is set at factory setting. 2nd clip
Stock main is 138. I have tried 135,138,140,145,150,160 to no avail.

Used carb cleaner to look for air leaks. Didn't find any
Checked reeds. Look good
Cleaned carb
Set float level checked, double checked, and triple checked
Cleaned air filter
Changed plugs
Fresh gas 93 octane running 32:1
Tried different carb
Top end is fairly new

That's all I can think of at the moment. Any help would be appreciated
Reply With Quote
Old 10-18-2018, 07:22 PM
Beginner Class
Join Date: Oct 2018
Last Online: 10-18-2018 07:30 PM
Location: Chocolatetown USA
Posts: 7

sounds like the jet needle is closing too early i would adjust the tab/tang on the float bowl a little higher. this is definately a fuel delivery issue. if the engine runs but shuts off its the carburetor. check out my youtube videos i have an cleaning and rejetting video for mikuni and keihin cv carburetors!!!
Reply With Quote

  All Things Moto! Dirtbike Forums > Dirt Bike - ATV - Suspension Forums > 2-Stroke Dirt Bike Forums > 2-Stroke Dirt Bikes - Yamaha

Thread Tools

Similar Threads for: Please help. YZ85
Thread Thread Starter Forum Replies Last Post
YZ85 Ring Gap gremmen 2-Stroke Dirt Bikes - Yamaha 6 04-12-2012 08:46 PM
04 yz85 04yz85 Product Reviews 2 01-10-2012 10:24 PM
Yz85? mars14 2-Stroke Dirt Bikes - Yamaha 2 09-19-2010 05:52 AM
yz85 rim yz80NICKyz80 2-Stroke Dirt Bikes - Yamaha 1 12-07-2009 03:25 PM
WTS: 02 KX265/ 05 YZ85 quadfather03 Classified Ads 5 05-31-2007 07:02 PM

All times are GMT -6. The time now is 06:29 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright ©2002-2019, JDub Consulting, Inc. All Right Reserved.