DtZ Posted August 3, 2009 Share Posted August 3, 2009 Got a 1975 yamaha dt175B running rough, need some info on how to adjust the carburator' floats. need to know if bending into the bowl= rich or lean? the measurement would help (how do u measure?) thanx! I can get it started idles for a few seconds then it pop's, then when i try to start it it pop's. to rich to lean ? help? the screw doesn't help im sure its the floats. thanx Link to comment Share on other sites More sharing options...
runningman Posted August 4, 2009 Share Posted August 4, 2009 The air screw which turns with a screwdriver should be 1.5 to 1.75 turns out. Screw it in all the way then back it out 1 and a half turns to start. The hand adjuster on the side of the carb with the spring can be screwed in all the way to start, and it will idle high to begin with once it is started, then back the hand screw out as the bike warms up to reduce the idle speed. I wouldn't bend the pins that the floats slide up and down on to adjust the levels in the carb, I've never heard of doing that. Just make sure that the pins are squeaky clean and that the floats move easially up and down on those pins. If your carb is clean, and assembled correctly it should fire and run ok. the needle and seat has a spring which interacts with the floats to control the gas level in your carb. By the way, if those float pins are bent I suspect that could be your whole problem, they should be arrow straight vertical. Kevin Got a 1975 yamaha dt175B running rough, need some info on how to adjust the carburator' floats. need to know if bending into the bowl= rich or lean? the measurement would help (how do u measure?) thanx! I can get it started idles for a few seconds then it pop's, then when i try to start it it pop's. to rich to lean ? help? the screw doesn't help im sure its the floats. thanx Link to comment Share on other sites More sharing options...
rayqualityman Posted August 6, 2009 Share Posted August 6, 2009 The air screw which turns with a screwdriver should be 1.5 to 1.75 turns out. Screw it in all the way then back it out 1 and a half turns to start. The hand adjuster on the side of the carb with the spring can be screwed in all the way to start, and it will idle high to begin with once it is started, then back the hand screw out as the bike warms up to reduce the idle speed. I wouldn't bend the pins that the floats slide up and down on to adjust the levels in the carb, I've never heard of doing that. Just make sure that the pins are squeaky clean and that the floats move easially up and down on those pins. If your carb is clean, and assembled correctly it should fire and run ok. the needle and seat has a spring which interacts with the floats to control the gas level in your carb. By the way, if those float pins are bent I suspect that could be your whole problem, they should be arrow straight vertical. Kevin Once you have straightened the float (if it is bent) you can adjust the fuel level on the float needle at the top you will see a small circlip on the nedle you will see 5 grooves make sure it is on the middle one (factory setting) you can adjust by moving up or down this may solve the problem Link to comment Share on other sites More sharing options...
DtZ Posted August 19, 2009 Author Share Posted August 19, 2009 Ok I have ajusted the float's ajusted the needle, ajusted the air to fuel mixture so these r my symptoms it seems to be running rich no matter what i do. floats at 21mm needle all the way lean & air to fuel screw 1/2 a turn out it starts but unless i open the throtle slowly it pops & dies , starts right up so.... that's that way. ive' done the opposite rich needle rich mixture, even worst, ive done factory specs & its between worst to just able to idle so should i consider its something else other than the carb. carb is clean all jets open ???? it runs if i keep it ideling high but if i open to full throtle gargle gargle & pop! ive taken this carb apart like 30 times. also with the first setting i mentioned the bike idle's fine ( the idle screw also does not raise the idle speed above 1400rpm with the lean setting i mentioned?) also it feels & revs great w this setting but, like i said from idle to wide open throtle it dies. help Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 19, 2009 Moderator Share Posted August 19, 2009 Ok I have ajusted the float's ajusted the needle, ajusted the air to fuel mixture so these r my symptoms it seems to be running rich no matter what i do. floats at 21mm needle all the way lean & air to fuel screw 1/2 a turn out it starts but unless i open the throtle slowly it pops & dies , starts right up so.... that's that way. ive' done the opposite rich needle rich mixture, even worst, ive done factory specs & its between worst to just able to idle so should i consider its something else other than the carb. carb is clean all jets open ???? it runs if i keep it ideling high but if i open to full throtle gargle gargle & pop! ive taken this carb apart like 30 times. also with the first setting i mentioned the bike idle's fine ( the idle screw also does not raise the idle speed above 1400rpm with the lean setting i mentioned?) also it feels & revs great w this setting but, like i said from idle to wide open throtle it dies. help What happens if you open the starter jet (inapropriately named ...choke)? Link to comment Share on other sites More sharing options...
rob dog Posted August 19, 2009 Share Posted August 19, 2009 Got a 1975 yamaha dt175B running rough, need some info on how to adjust the carburator' floats. need to know if bending into the bowl= rich or lean? the measurement would help (how do u measure?) thanx! I can get it started idles for a few seconds then it pop's, then when i try to start it it pop's. to rich to lean ? help? the screw doesn't help im sure its the floats. thanx I have a 1975 yamaha dt400b and all I know is that thing is touchy. I finally got it too idle great after after taking the carb apart and shotting W.D 40 through every orifice. I spoke to somebody where I work and they said when it pops and dies it's too lean. Try taking off the bowl and bending the float tab down slightly from horizontal. This should fatten it up. Also put a new plug in... Link to comment Share on other sites More sharing options...
DtZ Posted August 20, 2009 Author Share Posted August 20, 2009 it dies , i don't really ever have to use it? also i should mention im like 5000ft of altitude in denver CO. Link to comment Share on other sites More sharing options...
2-Stroke Dan Posted August 20, 2009 Share Posted August 20, 2009 Got a 1975 yamaha dt175B running rough, need some info on how to adjust the carburator' floats. need to know if bending into the bowl= rich or lean? the measurement would help (how do u measure?) thanx! I can get it started idles for a few seconds then it pop's, then when i try to start it it pop's. to rich to lean ? help? the screw doesn't help im sure its the floats. thanx When you say "pops", do you mean it backfires thru the carb? If so, I'd check the reed valves and/or crank seals. Link to comment Share on other sites More sharing options...
DtZ Posted August 20, 2009 Author Share Posted August 20, 2009 yeah, some times it sounds like a wet fart. i think it pop's from the exaust? ill try the floats again now that all the other settings r super lean ? thanx 4 the Help! Link to comment Share on other sites More sharing options...
rob dog Posted August 20, 2009 Share Posted August 20, 2009 yeah, some times it sounds like a wet fart. i think it pop's from the exaust? ill try the floats again now that all the other settings r super lean ? thanx 4 the Help! When you adjust the float tang with the carb off the bike, the carb should be up side down and then bend the tang down. Link to comment Share on other sites More sharing options...
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