cheslucy Posted March 30, 2009 Share Posted March 30, 2009 Hey guys after cleaning the hell out the carb 4 or 5 times and setting all of the needles and float to the correct positions the bike still will not idle. Any suggestions? Thanks by the way I've replaced the filter, spark plug, and air filter. Link to comment Share on other sites More sharing options...
Tylerman Posted March 30, 2009 Share Posted March 30, 2009 Throttle cable adjustments are next. If you have a service manual it should outline the procedure. In simple terms, you want to ensure the throttle slide (piston, whatever you call it) inside the carb is in the FULLY closed position, geez its been a while since I've done this and don't have a book in front of me, tighten/slacken the screw adjuster on top of the carb until the slightest movement of the cable moves the slide, then tighten/slacken the screw adjuster at the grip until you can turn the grip just a tiny bit before you feel the cable start to pull, that should set a good baseline. I don't know about the DT175, if it has an oil pump your manual will tell you how much slack to set in the cable for that component, some manufacturers allow for some slack, others want it tight. After this reset your idle speed using the appropriate screws on the carb. If adjusting your throttle cable doesn't help, you may have a crank seal going bad, I don't know the history of your bike if it has sat a long time the seals can dry out and leak. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 30, 2009 Moderator Share Posted March 30, 2009 Does it idle if you barely crack open the throttle? If so then you just need to adjust the throttle stop screw its the knurled one and turning it clockwise will increase idle speed, also check the mixture screw is set right it should be 1-1/4 to 1-1/2 turns out. Link to comment Share on other sites More sharing options...
cheslucy Posted March 30, 2009 Author Share Posted March 30, 2009 Does it idle if you barely crack open the throttle? If so then you just need to adjust the throttle stop screw its the knurled one and turning it clockwise will increase idle speed, also check the mixture screw is set right it should be 1-1/4 to 1-1/2 turns out. It only idles when I have the choke pulled out. Can the choke plunger or whatever you call it have something to do with it? Thanks Tylerman I will try that next. I also have a new pilot jet and gasket coming. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 30, 2009 Moderator Share Posted March 30, 2009 It only idles when I have the choke pulled out. Can the choke plunger or whatever you call it have something to do with it? Thanks Tylerman I will try that next. I also have a new pilot jet and gasket coming. That sounds like a. A blocked pilot jet...or b. A blocked bypass hole remove the pilot jet and hold it up to the light, you should see light through it if its not blocked. The symptoms you describe fit well with a blocked pilot jet, by operating the choke you are in effect doing what the pilot jet should do only more exagerated Link to comment Share on other sites More sharing options...
cheslucy Posted March 30, 2009 Author Share Posted March 30, 2009 That sounds like a. A blocked pilot jet...or b. A blocked bypass hole remove the pilot jet and hold it up to the light, you should see light through it if its not blocked. The symptoms you describe fit well with a blocked pilot jet, by operating the choke you are in effect doing what the pilot jet should do only more exagerated What is a blocked bypass hole? Thanks Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 30, 2009 Moderator Share Posted March 30, 2009 What is a blocked bypass hole? Thanks Look down the carb barrel from the manifold side towards the throttle slide, you will see one or two holes in the bottom of the barrel, how many can you see? if its just one then this is the pilot hole and if its two it will be pilot and bypass holes, both these need to be clear for no throttle and low throttle performance. Regarding the hole in the carb barrel nearest the manifold side...Many carbs have a two hole idle system which gives better low speed and mid range throttle response than the simpler one hole type. At very small throttle openings, the bypass hole and not the pilot hole actually provides the engine with fuel. Instead the pilot hole acts as a supplementary air bleed to further atomise the fuel airafter it passes through the idle jet. As the throttle opens wider, the pilot hole too begins to spray fuel. This serves to supply the engine with additional fuel until the air speed throgh the carb increases enough to start the main jet and needle valve flowing fuel into the engine Link to comment Share on other sites More sharing options...
GaSo Posted March 30, 2009 Share Posted March 30, 2009 wouldn't hurt to consider it may also be too much air at idle, since the choke increases the amount of fuel in the mixture artificially. leaks around the carb holders if they're cracked the whole way through, ratty air filters letting too much air in, a few less common things, etc etc... Link to comment Share on other sites More sharing options...
cheslucy Posted April 21, 2009 Author Share Posted April 21, 2009 Got a rebuild kit for the carb and it idles fine. The only thing now is it is a little choppy in first and second gear. Once you get it to third it takes off. Any ideas as to why it kind of hesitates in first and second? Thanks Link to comment Share on other sites More sharing options...
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