Ive fitted a new pilot screw (or air screw) on the carb of a yz85 2005 what is the correct setting for it starting from being screwed right in as far as it will go.i do understand all bikes are set up differantly and i can play with it once its running but i would like to no what is the correct starting point.
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Re: pilot screw setting.
Stock it would be around 2 turns out.
These bikes shipped with only one jet needle (unlike other Yamaha's) the bike's factory jetting is 45 pilot, NBKF needle on the 2nd clip from the top, and 138 main. This bike tends to run a little rich off the bottom, so I'd recommend running a 42 pilot instead. When it's really hot out (over 90) you can run the 135 main jet.
Screwwing with carbs is fact of life with these bikes - you will have to do some tweaking no matter what.
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I would check a few things. First off make sure the throttle cable is adjusted correctly. Second, try opening the throttle half way and letting go you should hear the inside parts of the carb click as they seat. Third, find the idle adjuster screw turn this anti clockwise and see if the idle speed drops down. Fourth check the choke mechanism is working properly choke/cold start forces a rich mixture to the engine and increases the idle revs.
it is worth checking the pilot air screw is adjusted correctly. Hope this helps.
I would suggest removing the carb again, take the top off where the cable[s] enter the carb body. Check all cables move freely, make sure needle is in correct position. Remove float bowl, jets and adjuster screws, put all pieces, except top/cable assy, into a metal container. Fill container with carb cleaner or meths to just cover the contents. Leave for at least 12 hours to soak. Dry off all parts re-assemble all parts and finally re- fit top assy, re-fit carb to bike. At this stage make sure the pilot air screw is correctly adjusted by gently turning it into the carb body until it stops do not exert any pressure. Check your user manual and undo the screw by the recommended amount of turns. I have used this method loads of time and it has always worked for me. Good luck.
Most likely the jets are 'gummed up'. I would first completely disassemble the carb and clean everything compressed air works well to clean out the tiny openings etc. Once you've cleaned everything and reassembled the carb, you would ideally want to have drained the gas tank and lines and replenish with fresh fuel.
It sound like the choke is stuck on or the pilot air screw is crudded up. Before removing pilot air screw make sure you know how many turns out it has to be adjusted to. Remove and clean the screw make sure the small hole this screw works with in the carb is not clogged. A thin brush fibre can be used to check this (do not use any thing metal). If necessary use a carb cleaner to remove any debris. Replace the pilot air screw very gently screw/turn into the carb until it becomes firm do not tighten any further. You now need to turn it back the number of turns the manufacturer states in the service manual.
Check the choke operation and make sure the cable/operating mechanism is/are working freely. What ever choke type is fitted in the carb i.e. slide, butterfly valve etc. it must work freely.
The screw I think you are adjusting is the idle mixture screw, and will only make a differnce at idle You set at the smoothest idle . If power in 1 and 2 is the problem, then there is something else, make sure the carb is clean, the exhaust is not blocked , the air filter is clean and relatively new,valve clearances? are ok, new spark plug , new oil, and then start looking at the jetting. up to 1\4 throttle -pilot jet around mid range -needle position top end -main jet. try riding with and without choke to get some idea, if it runs better with some choke then it is lean
Take out the pilot air screw[s] from the carbs and remove the pilot jets. Check for dirt and make sure the hole in the jet is clear. Check the pilot air screw for dirt wipe clean carefully as the inboard tapered section is easily damaged.
Check the float bowls are clean remove main jets and check they are clear of any dirt/debris etc.
Make sure when you replace the pilot air screws you screw them in carefully until they just stop. Do not over tighten in any way. (Be very gentle please). Then turn them out the correct number of turns as stated in you manual.
The pilot jets control starting and throttle opening up to about halfway.
By your description, it sounds like the pilot jet is plugged in the carb. Remove carb and clean thoroghly with carb cleaner and air, making sure that all jet passages are clear. Make sure that washer and "o" ring are present on fuel mixture screw, if so equipped. Make sure float level is correct.
There isn't really a "correct" setting for the pilot screws. They're all set differently from the factory, based on the individual carb settings. You'll basically need to start at a baseline of 1.5-2 turns from seated (lightly seated) and work them in/out from there.
The first thing you should do before you go bothering to mess with settings, though, is clean your carbs thoroughly. Blow carb cleaner and compressed air through any of the passages in the carb body you can find, except the ones that lead up to the diaphragms, if you have CV carbs. You only need about 30 PSI if you can regulate your line pressure. Even a can of compressed air from Kmart will do, the stuff they use to blow out keyboards and such.
If you're really into time consuming stuff, you can buy a couple cans of compressed butane lighter fluid, and blow that through the pilot holes and such... you'll need a straw that fits on it, though. You'll be amazed what a good carb cleaning can do for a bike, as well as carb synchronizing. You can find specific directions for your fuzzer's carbs on just about any bike forum.
Remove the throttle stop adjuster and the air screw adjuster and spray carb cleaner in the holes. Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two adjusters down. Only screw these in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. Turn the pilot screw 1/4 turn counter clockwise. Check the float level. Before putting the slide back in the throat of the carb, move the clip on the jet needle one notch lower.Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. Adjust the idle speed with the Throttle stop screw. This process should get you back on the road. A “very helpful” rating for this answer?Thanks!