CT_Addict Posted August 25, 2010 Share Posted August 25, 2010 I bought this 74' DT 175 in the desert last weekend and it ran great. I get it up here where I live at 7500ft altitude and it boggs out in the first 1/4 or so of throttle and doesn't want to idle unless the choke is on, seems to run good in the top end though, we ride up from here to about 9000ft. Can anyone with experience advise me on jetting this high? Thanks for any help Link to comment Share on other sites More sharing options...
Vez Posted August 26, 2010 Share Posted August 26, 2010 I bought this 74' DT 175 in the desert last weekend and it ran great. I get it up here where I live at 7500ft altitude and it boggs out in the first 1/4 or so of throttle and doesn't want to idle unless the choke is on, seems to run good in the top end though, we ride up from here to about 9000ft. Can anyone with experience advise me on jetting this high? Thanks for any help Higher up you go the thinner the air gets, so you will probably need to put a smaller jet in to give less fuel to mix with the thinner air. But, I would try and adjust the air/fuel mixture screw first as this has the most effect in the lower part of the rev range afaik. Failing that buy a few different jets and then its trial and error till one works well. HTH Vez. Note* I could be wrong, it is 1 am . Link to comment Share on other sites More sharing options...
nayruf Posted August 26, 2010 Share Posted August 26, 2010 Hi , i have been playing with my DT carb to get it back to the original settings, I downloaded this manual http://www.mikuni.com/pdf/vmmanual.pdf page 13 has some info on altitude problems, the manual might not give you the answer but the mikuni web site might give more ideas. hope this helps in a small way Link to comment Share on other sites More sharing options...
CT_Addict Posted August 26, 2010 Author Share Posted August 26, 2010 Hi , i have been playing with my DT carb to get it back to the original settings, I downloaded this manual http://www.mikuni.com/pdf/vmmanual.pdf page 13 has some info on altitude problems, the manual might not give you the answer but the mikuni web site might give more ideas. hope this helps in a small way Thanks Link to comment Share on other sites More sharing options...
CT_Addict Posted August 26, 2010 Author Share Posted August 26, 2010 Higher up you go the thinner the air gets, so you will probably need to put a smaller jet in to give less fuel to mix with the thinner air. But, I would try and adjust the air/fuel mixture screw first as this has the most effect in the lower part of the rev range afaik. Failing that buy a few different jets and then its trial and error till one works well. HTH Vez. Ok Thanks Note* I could be wrong, it is 1 am . Link to comment Share on other sites More sharing options...
nayruf Posted August 26, 2010 Share Posted August 26, 2010 Hi, just a suggestion , Before I bought new a new jet I would lower the needle in the throttle slide, don't know if doing that would help but working on the assumption that the lower the needle in the seat the less fuel would be delivered to the engine Link to comment Share on other sites More sharing options...
CT_Addict Posted August 27, 2010 Author Share Posted August 27, 2010 Hi, just a suggestion , Before I bought new a new jet I would lower the needle in the throttle slide, don't know if doing that would help but working on the assumption that the lower the needle in the seat the less fuel would be delivered to the engine I lowered it 1 notch and it did help but still started loading up, tomorrow I will drop it 1 more (the last position) but I bet I will have to go with a smaller jet. Thanks for the help Link to comment Share on other sites More sharing options...
CT_Addict Posted August 31, 2010 Author Share Posted August 31, 2010 Hi, just a suggestion , Before I bought new a new jet I would lower the needle in the throttle slide, don't know if doing that would help but working on the assumption that the lower the needle in the seat the less fuel would be delivered to the engine This did it, I lowered the needle all the way and adjusted the air a little bit and it runs and idles great at 7500-7800 so far Thanks for the tip Daniel Link to comment Share on other sites More sharing options...
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