josh_350 Posted November 25, 2018 Report Share Posted November 25, 2018 Hey guys first post happy to be here so I got a problem just did a top end rebuild wiseco stock bore pro circuit pipes reed spacers boyesen reeds and that's about it so when I was tuning my carbs the needle was too rich but it started first kick everytime I moved the needle up one so now it runs good but I have to use starting fluid to start it and once it gets warmed up itll idle for a good minute then eventually die I changed my jets with some ebay jet kit and it started first kick and revved fine when it was in neutral but on pulls it would break up really really bad was wondering what I should do I put the old main jets back in and pulls fine now,any ideas?? Any help is great thx guys have a good day Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
97Screamer Posted November 25, 2018 Report Share Posted November 25, 2018 6 minutes ago, josh_350 said: Hey guys first post happy to be here so I got a problem just did a top end rebuild wiseco stock bore pro circuit pipes reed spacers boyesen reeds and that's about it so when I was tuning my carbs the needle was too rich but it started first kick everytime I moved the needle up one so now it runs good but I have to use starting fluid to start it and once it gets warmed up itll idle for a good minute then eventually die I changed my jets with some ebay jet kit and it started first kick and revved fine when it was in neutral but on pulls it would break up really really bad was wondering what I should do I put the old main jets back in and pulls fine now,any ideas?? Any help is great thx guys have a good day Sent from my SM-G965U using Tapatalk A lot of the ebay jets are junk. Wrong sizes etc. If it runs good with the old jets leave those in, what am I missing? In general the best write up I've found for tuning carbs is on the Duncan Racing website. If you follow the instructions you'll be dialed in and understand your bike better for future changes. https://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 A lot of the ebay jets are junk. Wrong sizes etc. If it runs good with the old jets leave those in, what am I missing? In general the best write up I've found for tuning carbs is on the Duncan Racing website. If you follow the instructions you'll be dialed in and understand your bike better for future changes. https://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdfI'll have to look at that link thanks for the help idk because sometimes before powerband I still feel like theres a tad of breakup so I might put bigger jets in and see if that helps Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
97Screamer Posted November 25, 2018 Report Share Posted November 25, 2018 There are three jetting circuits you'll need to set independently. That write up above talks about them also. Pilot circuit is startup and 0-1/4 throttle, needle 1/4-3/4 and main 3/4 - full. Of course there are overlaps etc, these are general numbers. Tune them one at a time or you'll drive yourself crazy randomly switching jets. http://iwan-ae.info/yz250-jetting-chart/yz250-jetting-chart-overview-101-all-offroad-com-jet/ Quote Link to comment Share on other sites More sharing options...
dano3 Posted November 25, 2018 Report Share Posted November 25, 2018 i second the duncan carb setup post, that is what i used. What carbs are you using and how are you setting idle speed? Im guessing stock carbs but it would be helpful to know your jetting and temperature/elevation. Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 i second the duncan carb setup post, that is what i used. What carbs are you using and how are you setting idle speed? Im guessing stock carbs but it would be helpful to know your jetting and temperature/elevation. Stock carbs idle is set by throttle temp rn is around 30-50 degrees Fahrenheit sadly idk elevation Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
dano3 Posted November 25, 2018 Report Share Posted November 25, 2018 5 minutes ago, josh_350 said: Stock carbs idle is set by throttle temp rn is around 30-50 degrees Fahrenheit sadly idk elevation Sent from my SM-G965U using Tapatalk read the links 97screamer posted to better understand which circuits do what and how those changes affect things. It sounds like your current problem is hard starting but it pulls clean through the powerband? If thats the case you should set your idle using the idle screw kit and then make sure your carbs are synced correctly (carb sync tool from FAST racing is best). Remember that the colder it gets the more fuel/larger main jets you will need. What size main jets did you put back in after the ebay kit? Are you running 27.5 pilot jets? Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 read the links 97screamer posted to better understand which circuits do what and how those changes affect things. It sounds like your current problem is hard starting but it pulls clean through the powerband? If thats the case you should set your idle using the idle screw kit and then make sure your carbs are synced correctly (carb sync tool from FAST racing is best). Remember that the colder it gets the more fuel/larger main jets you will need. What size main jets did you put back in after the ebay kit? Are you running 27.5 pilot jets? My idle is through my throttle right now but I believe they were 25s for the mains Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
dano3 Posted November 25, 2018 Report Share Posted November 25, 2018 My idle is through my throttle right now but I believe they were 25s for the mains Sent from my SM-G965U using TapatalkSetting it through the throttle is hard to get both carbs synced accurately and really isnt the right way to do it. Idle screws makes it much easier and accurate. 25 is a pilot jet size and you should be running a 27.5 pilot. Whats the main jet size. It should be a number in the high 200s or low 300s Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 Setting it through the throttle is hard to get both carbs synced accurately and really isnt the right way to do it. Idle screws makes it much easier and accurate. 25 is a pilot jet size and you should be running a 27.5 pilot. Whats the main jet size. It should be a number in the high 200s or low 300s Sent from my iPhone using TapatalkYah I agree thats just the way my dad did it I'm on my now and trying to learn as much as I can and when I said 25 I was talking about main so I'm guessing my main is a 250Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
dano3 Posted November 25, 2018 Report Share Posted November 25, 2018 Yah I agree thats just the way my dad did it I'm on my now and trying to learn as much as I can and when I said 25 I was talking about main so I'm guessing my main is a 250Sent from my SM-G965U using Tapatalk250 main would be pretty lean for your setup and temperature. Where do you live so we can figure out your elevation? You should be closer to a 300 main and 27.5 pilot with those mods and temperature. There are some good videos on youtube to help you get into the stock carbs, make adjustments, and check jetting. Def start with confirming your main jet and pilot jets and update us. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 250 main would be pretty lean for your setup and temperature. Where do you live so we can figure out your elevation? You should be closer to a 300 main and 27.5 pilot with those mods and temperature. There are some good videos on youtube to help you get into the stock carbs, make adjustments, and check jetting. Def start with confirming your main jet and pilot jets and update us. Sent from my iPhone using TapatalkOk will do thank you for the suggestions the help is very much appreciated!Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
kawa110 Posted November 25, 2018 Report Share Posted November 25, 2018 Tors caps removed? Quote Link to comment Share on other sites More sharing options...
josh_350 Posted November 25, 2018 Author Report Share Posted November 25, 2018 Tors caps removed? Yes it has a twist throttle now Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
josh_350 Posted December 4, 2018 Author Report Share Posted December 4, 2018 250 main would be pretty lean for your setup and temperature. Where do you live so we can figure out your elevation? You should be closer to a 300 main and 27.5 pilot with those mods and temperature. There are some good videos on youtube to help you get into the stock carbs, make adjustments, and check jetting. Def start with confirming your main jet and pilot jets and update us. Sent from my iPhone using TapatalkOk so I put 300 mains in it and it did sound a lot richer and it idled really good once I readjusted my slides but I think it was running almost too rich so put 290s and it didnt help at all so I put the 300s back in and moved the needle clip one step leaner and it kind of runs like a dog any suggestions??Sent from my SM-G965U using Tapatalk Quote Link to comment Share on other sites More sharing options...
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