Paullaith Posted June 25, 2012 Posted June 25, 2012 More problems with my DT lol and need help as im learning slowly. Basically when you rev it the revs drop back down slow, ive tried wd40 round the cylinder head and inlet manifold and ive cleaned the carb but still no joy. Has anyone had this problem before?
Moderator Airhead Posted June 25, 2012 Moderator Posted June 25, 2012 try turning in (clockwise) the air mixture screw 1/4 of a turn and test again, if same repeat. If you cant sort it before the screw gentlly seats you might have to fit a bigger pilot jet to the one fitted now. This assuming you have no air leaks anywhere!
Paullaith Posted June 25, 2012 Author Posted June 25, 2012 Ive tried the screw it just made the idle go up. There is defo no air leaks ive made sure of that.
Moderator Airhead Posted June 25, 2012 Moderator Posted June 25, 2012 Ive tried the screw it just made the idle go up. There is defo no air leaks ive made sure of that. which screw did you try? I didnt say the idle AKA 'throttle stop' screw...I said the air mixture screw, its a small one and may be recessed somewhere on the filter side of the carb slide
Paullaith Posted June 25, 2012 Author Posted June 25, 2012 Ahh the heads rounded off on that one it wont budge.
Moderator Airhead Posted June 25, 2012 Moderator Posted June 25, 2012 Ahh the heads rounded off on that one it wont budge.
Paullaith Posted June 25, 2012 Author Posted June 25, 2012 Will i be able to get to it from inside the carb?
Moderator Airhead Posted June 25, 2012 Moderator Posted June 25, 2012 Will i be able to get to it from inside the carb? NO! Is there anything else i can try? you could try a bigger pilot jet the next size up, the size is stamped on the jet
AndyDtr08 Posted June 25, 2012 Posted June 25, 2012 I would order the screw from Yamaha or even buy a replacement carb from ebay. It seems someone had tampered with your carb alot and is probably the main cause of your problems. Spend 30-50 on a nice condition one on ebay and have it apart, clean it, check jetting and then set up yourself to know its all correct. I beleive the air screw should be 1 and 1/2 turns out from fully screwed in. start with both air and idle all the way in. Then use the idle to bring the revs down to 1.5k Screw the air screw 1/2 turn ( this will bring the revs up) Screw the idle out again gently to bring it down to 1.5k Screw the air screw 1/2 turn more (now it is 1 turn out) Screw the idle out again gently to bring it down to 1.5k Screw the air screw 1/2 turn more (now it is 1 and 1/2 turns out and in its optimum position) You can now adjust the idle screw to whatever you want the idle engine speed to be ( 1- 1.5k i would guess) ***Check that 1 and 1/2 turns is the optimum setting but I have found that to run nicely*** When you say rounded? The air screw is a flat head screw, are you sure you are looking at the right one? If i get a chance I'll photo a carb and circle and label the two. The air screw is in a recess to the right of the idle as Airhead said. It's kinda 'down a tube'. If you think the air screw is not set right, avoid running the bike. Too much air will cause the mixture to be lean and the engine will run too hot and you'll hole the piston. Without being rude, if you don't know what you are doing, research it before you mess around or you'll learn the hard way.
Paullaith Posted June 25, 2012 Author Posted June 25, 2012 Ok thank you great info il have a look for a carb i think as mine isnt looking in the best condition anyway. Also my bike was running fine the other day its only just started doing this and i havnt touched any thing.
Paullaith Posted June 26, 2012 Author Posted June 26, 2012 Ive found a carb for £40 so going to pick that up tomorrow.
AndyDtr08 Posted June 28, 2012 Posted June 28, 2012 Good plan. check the air screw is intact! Haha. If not you can buy it here http://www.yamahamotorcyclespares.co.uk/spares/partImage.asp?GPN=3mb141040000&uid=0
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