robert.b.west Posted April 26, 2009 Report Posted April 26, 2009 My buddy has a ds650 and we can only get it to idle every time we give it gas it backfires thru the carb. we have checked the the parking brake rev limiter and i have played around with the air screw and the needle position and cant get anything to work. Can anyone give me at lease some positions for the needle airscrew and jet sizes and possibly some ideas on what it could be. Quote
AKheathen Posted April 26, 2009 Report Posted April 26, 2009 My buddy has a ds650 and we can only get it to idle every time we give it gas it backfires thru the carb. we have checked the the parking brake rev limiter and i have played around with the air screw and the needle position and cant get anything to work. Can anyone give me at lease some positions for the needle airscrew and jet sizes and possibly some ideas on what it could be. ok, ifrst off, what's the situational info? did it suddenly start running like this, or was it a rebuild or mods that made it start acting up. it could be a number of things, from electrical, to valve timing, or interenal damage. make sure both plugs/coils are firing, and check compression. Quote
captainhowdie Posted April 26, 2009 Report Posted April 26, 2009 My ds650 was doing the same thing. Ended up being the cdi box Quote
robert.b.west Posted April 26, 2009 Author Report Posted April 26, 2009 He stopped riding it about a year ago when it started overheating. It turns out that it was the water pump. After sitting for this long it just does not want to rev up. We put new gas in it, he cleaned the carbs out. He did say the night before that he could rev it up but on half choke. I am stumped, it seems like the rpms are being limited by the spark but he said it would rev the night before. Also is there a way to test the cdi box to tell if there is something wrong with it. thanks Quote
Tf705 Posted April 26, 2009 Report Posted April 26, 2009 this definetley sounds like timing is way off. maybe cdi is bad. Quote
mopar1rules Posted April 26, 2009 Report Posted April 26, 2009 usually when they backfire thru the carbs, the timing is off, but you said he can only rev it up when its on 1/2 choke or so, so that's telling me something is pluged or not set right in the carbs. if he has to have the choke on some to run/rev-up, then its not getting enough fuel thru its other fuel circuits. check carbs again and electrical components...like cdi, coil, etc. how about valve clearances? Quote
robert.b.west Posted April 26, 2009 Author Report Posted April 26, 2009 Thanks for all the help i am more of a 2 stroke guy so this may be out of my abilities. But i will see what i can do. Quote
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