babuski76 Posted October 8, 2008 Share Posted October 8, 2008 Hi all. I have just got a DT 400 from 75. It hasn't been driven very much since '82. I will start if the sparkplug is dry, and no choker is used. But it won't take the throttle, then it's stops, and the spark plug is wet as hell. Does anyone have some input what I can do? Some time it 4 strokes. Regards Rasmus in Denmark Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 8, 2008 Moderator Share Posted October 8, 2008 Hi all. I have just got a DT 400 from 75. It hasn't been driven very much since '82. I will start if the sparkplug is dry, and no choker is used. But it won't take the throttle, then it's stops, and the spark plug is wet as hell. Does anyone have some input what I can do? Some time it 4 strokes. Regards Rasmus in Denmark Hi Rasmus, I can suggest five things 1: Check the carb floats are not leaking, Hold them with pliers in a container of hot water, watch out for bubbles (be careful not to bend the tang that operates on the float needle valve) 2: Check the float height is correctly set to 23mm 3: Using a good magnifying glass and a small light source (such as on a mobile phone) have a look down the pilot air passage and verify that the air jet is clean, this is often overlooked, if you use a compressed air line you should be able to blow through this to find air comes out where the emulsion tube (needle jet) screws in to the carb body, also check the very small holes in the side of the emulsion tube are clear. 4: Try again with the air filter removed, if it improves clean the filter 5: Carbon build up around the exhaust port, scrape clean if necessary, Best done with the head off and a rag covering the piston crown. Link to comment Share on other sites More sharing options...
Twin Shock Posted October 8, 2008 Share Posted October 8, 2008 Hi all. I have just got a DT 400 from 75. It hasn't been driven very much since '82. I will start if the sparkplug is dry, and no choker is used. But it won't take the throttle, then it's stops, and the spark plug is wet as hell. Does anyone have some input what I can do? Some time it 4 strokes. Regards Rasmus in Denmark Completely disassmeble the carburator and clean,and then clean somemore. I don't know if you have "Berryman" parts cleaner where you are but it does a great job on removeing dirt and varnish deposits. Replace "ALL" the rubber "0" rings and seals and re assemble. Hopefully you don't have a problem with the CDI but take care of the carb first. Also make sure the airfilter is not dry rotted and your sucking it into the carb. Link to comment Share on other sites More sharing options...
babuski76 Posted October 9, 2008 Author Share Posted October 9, 2008 The air filter was almost not eksistig, so I made a new one. I'll have an other look at the carb. I hope to find some more rubbish in it. how do I set the float to 23 mm? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 9, 2008 Moderator Share Posted October 9, 2008 The air filter was almost not eksistig, so I made a new one. I'll have an other look at the carb. I hope to find some more rubbish in it. how do I set the float to 23 mm? Turn the carb upside down Remove the float bowl. carefully remove the float bowl gasket, you should really fit a new one but i have got away re using the old one many times. now lift the floats until the tab in the centre just begins to touch the spring loaded needle valve, now measure the height of the float from the gasket face using either a vernier of an engineers ruler, you will notice a notch in the lip around the gasket face where you can get your rule in. bend the tab so you get the required float height look out for debris blocking the air jet as i said earlier, especially since your filter has been in bad shape Did you check that there is no debris from your old filter inside the reed valve unit, that would upset things nicely! Link to comment Share on other sites More sharing options...
babuski76 Posted October 9, 2008 Author Share Posted October 9, 2008 I'll have a look at the float again. Yes I checked the membrane, they where fine, nothing of the old air filter in there.. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 9, 2008 Moderator Share Posted October 9, 2008 I'll have a look at the float again. Yes I checked the membrane, they where fine, nothing of the old air filter in there.. I know your carb is overflowing, this will cause the bike to run rich and blacken the spark plug. the carb float should control the level in the float bowl by closing off the needle valve, even with the petcock on it should still function and not overflow. you need to inspect the needle shutoff valve and seat for wear and replace as needs be. use your clymer manual for how to do this Link to comment Share on other sites More sharing options...
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