Question about 2002 Yamaha TT-R 225
Hi, Slayport it should be noted that the "AIR FUEL" mixture screw adjustment "ONLY" manages your idle and has no effect on any other circuit also any intake leaks must be repaired before the A/F adjustment procedure can be performed otherwise you will never obtain a proper idle and you will waste a lot of time chasing the impossible. The A/F mixture screw's purpose is to fine tune the fuel charge entering the combustion chamber. The following applies to both 2 and 4 stroke engines:
1. The mixture screw may be sealed at the factory with a Welch Plug please review the following video for removal.
2. The mixture screw manages a range of 3 complete 360-degree counterclockwise turns from the bottom/closed position.
3. The mixture screw should have a spring and o-ring for tension and sealing integrity.
4. Turn the mixture screw clockwise until it gently bottoms out, this makes the fuel charge very lean and the engine should not idle if it does then the pilot/idle jet is too big and needs to be replaced with the next size smaller.
5. Turn the mixture screw 1 and 1/2 turns counterclockwise to establish a baseline for starting the engine.
6. To fine-tune the idle circuit, adjust the mixture screw 1/4 turn in or out to achieve maximum idle RPM, wait 15 seconds between each adjustment for the idle to settle.
7. Never go past 3 full turns out this will make the fuel charge rich, foul plugs, and produce black smoke out of the exhaust, if the engine RPM keeps increasing past 3 turns the pilot/idle jet is too small and needs to be replaced with the next size larger.
7. After achieving maximum idle back out the mixture screw another 1/8 of a turn then adjust the throttle cable idle stop screw to 950-1050 RPM.
8. This procedure works great on 99% of all engines, for the 1% that demand a more robust throttle response on aftermarket monster fuel delivery systems additional tweaking outside the box may be necessary.
For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
TTR225 air screw adjustment
Life On 2 Wheels
OEM parts for Yamaha
Yamaha TTR225S Owner Manual
Posted on Jun 01, 2017
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
Here's a link to this great service
Posted on Jan 02, 2017
Tips for a great answer:
Sep 23, 2014 | Motorcycles
Jan 08, 2018 | 2003 Yamaha TT-R 225
Apr 08, 2013 | 2003 Yamaha TT-R 250
Dec 11, 2012 | 2008 Yamaha TTR230
Jun 29, 2011 | 2004 Yamaha TT-R 225
Jun 21, 2011 | 2002 Yamaha TT-R 225
Dec 31, 2010 | 2002 Yamaha TT-R 125
Oct 15, 2010 | 2004 Yamaha TT-R 225
Feb 05, 2010 | 2003 Yamaha TT-R 225
Nov 13, 2009 | 2002 Yamaha TT-R 125 L
1,070 people viewed this question
Usually answered in minutes!
Step 2: Please assign your manual to a product: