Hi, Markaula 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. https://www.youtube.com/watch?v=wAXcksgvDkM
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.
8. 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.
9. 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 for viewing or printing please click on the blue links below. Good luck and have a wonderful day. https://www.youtube.com/watch?v=pAM5-OmM47U https://www.youtube.com/watch?v=yYPD-_y_CBQ Suzuki RF 900 Service Manual https://www.partsfish.com/oem-parts-for-suzuki http://mybikemanuals.com/suzuki
Its definately Metric (mm) unless someone has changed them.
Its will be a 12mm, 14mm, 15mm, 17mm, or a 19mm (one of these)
if it was any smaller it would be a 10 mm but i've never saw one with 10 mm.
but i have saw some with metric allen heads.
It's most likely that your fork springs are sagging, your oil needs replacing and you should adjust the preload and damping to get the setting you like. If you have an early model without preload and damping adjustment, then replace the springs with Hagon (
Varnish builds up after awhile and causes this problem..gas can go stale in less than 8 weeks if the bike sits for awhile...Go to your local auto parts store and buy a can of Seafoam...pour 1/2 the can in on a full tank of fresh gas...run the tank down as fast as u can...pour the rest of the Seafoam in the next tank of fuel...you will see an improvement...Would be a good idea to replace fuel filter after the second tank, any debris or sludge in the tank will be cleaned out also.. never run your bike without good air filtration, this is bad karma. K & N makes a good high flow filter. As far as motor oil...i recommend a full synthetic like Lucas... Mobil 1 or Vavoline...change it every 3500 miles. Good luck, i hope this helps...please rate me a fixya.