Johnny.B Posted July 14, 2014 Share Posted July 14, 2014 Hello again, Friends! So I posted a while back about my 1975 Yamaha DT400 having trouble kick starting, which was initally resolved for a while. She would putt around like the old dog should and was quite a blast!! But sadly enough she seems to be sick again. On the way home from work recently I was crusing about 5-10 miles down a straight road at 40MPH and when I arrived at a stop light, I noticed she was kinda struggling (cough and sputtering). Gave her a bit of gas and she seemed to release herself from it til I arrived at the gas station, then began to cough and sputter again. Shut her off, tried to kick her over, no dice. I tried resetting her carbureter idle screw and such which gave her life at neutral, but now when I try to give her throttle in acceleration, she will cough and sputter once more, most of the time dying, if not then giving me the shakiest ride of my life. I also noticed when trying to kick start her, she will more than frequently kick back or backfire, so my foot is now a black and blue mess. What I have done so far: Checked fuel lines Checked fuel filters, both clean. (Yeah, got two on her, can't be too safe.) Checked carbureter, clean as a whistle. I have not adjusted the jets for my altitude yet. Next locations I am looking at are possible the boot from the carb to the cylinder, which may have a tear allowing excess air flow, or maybe my carb is running incredibly rich. I say this because it always overflows if I don't remember to shut off the fuel lines, which is puzzling because I have set it to factory height. It's one of the indepenent floats (Has two separate floats with the float lever sitting atop from them. Hope I'm getting my words right) and I have the lever set at 0.68 in. She has about half a gallon left and am on reserve. I am still shy of Yamadog servicing since this is my first bike of only three weeks, so if my logic sounds amateur I don't concur. Any knowledge of this issue is greatly appreciated. Thank you! Link to comment Share on other sites More sharing options...
blackhat250 Posted July 14, 2014 Share Posted July 14, 2014 Ok jonny" that floatvalve may be leaking , [ no amount of height setting will stop fuel leak,] or DO them floats actually float,, . check them . carb boot needs fixing , it will be lean if air pulls thru it, ,,,get back when all these are fixed ,, Here was mine in 2010 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted July 14, 2014 Moderator Share Posted July 14, 2014 Two filters in series is excessive isnt it, is this arrangement giving a slow fuel feed to the carb? Link to comment Share on other sites More sharing options...
Johnny.B Posted July 14, 2014 Author Share Posted July 14, 2014 What a beauty! And it isn't, Airhead Checked the fuel line and gas pours through fine. So far today I did a thorough carb cleaning (Taking out the jets and whatnot,) checked the boot and saw no holes so I just remade the gaskets from the boot and reeds to the block, though the reeds will need replacement too. I will check on that float valve shortly. Still coughs and sputters. I remember when I removed the muffler for painting there was a rattling near the end of it where it connects to the stinger, and discussing with someone else they mentioned that it could be an issue of the exaust pipe getting clogged at high RPM's, where it seems to be struggling mostly. I have a spare from a 250 I will be swapping out when the bugger gets cold enough. Link to comment Share on other sites More sharing options...
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