CRS Posted February 21, 2010 Share Posted February 21, 2010 Hiya all. I have a 77 DT-400 This is the first 2 stroke bike I've ever owned. It has 8k miles on it and it looks to be in pretty good shape. I want to get it looking and running great. I would like some help in locating repair manuals or repair procedures so I can start getting it in tip-top shape. Right now it starts great (now that I learned the trick to a kick start) and runs strong. When I'm driving it, unless I'm actually advancing the throttle, it makes a banging/knocking sound and it kind of jerks forward (like when you don't know how to drive a stick). It's almost like a rough idle. If I squeeze the clutch or increase the throttle, it smooths out. The after riding it for a while (about an hour or so) it will occasionally surge and when I come to a stop the engine will cut out unless I give it gas. If it does stop I have to wait about 15-20 minutes till I can get it to start. Any help would be appreciated. I like this bike a lot and would love to get it running smooth. I think I might need to make some adjustments to the carb or clean it up. I'm not sure where to start though. Robert Link to comment Share on other sites More sharing options...
blackhat250 Posted February 21, 2010 Share Posted February 21, 2010 Hi ther Welcome " Now then sounds like the crank seals are shot.[ hardened] due to sitting around , poor starting is common sign, also surging, poor idle speed [ high reving when hot] due to the excess air being sucked into the crankcase via the fucked seals, rebuild is only solution. Link to comment Share on other sites More sharing options...
CRS Posted February 27, 2010 Author Share Posted February 27, 2010 Is there any way to check this? It looks to be in pretty good shape. I mean it looks pretty clean almost like it was rebuilt not too long ago. I bought this from a guy who got it as partial payment for rebuilding the engine for someone. He said he he did not have the cylinder apart but he cleaned the carb and did work on the brakes. He mentioned that he did not have a manual for it and could not find one on-line. Also, if I were to rebuild the engine, what parts should I have on-hand before I start. Obviously if I pull it apart and the piston has a hole in it I'll need to replace it but I would like to know what the most likely parts I'll have to replace. Thank you for any help you can give me. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted February 27, 2010 Moderator Share Posted February 27, 2010 Is there any way to check this? It looks to be in pretty good shape. I mean it looks pretty clean almost like it was rebuilt not too long ago. I bought this from a guy who got it as partial payment for rebuilding the engine for someone. He said he he did not have the cylinder apart but he cleaned the carb and did work on the brakes. He mentioned that he did not have a manual for it and could not find one on-line. Also, if I were to rebuild the engine, what parts should I have on-hand before I start. Obviously if I pull it apart and the piston has a hole in it I'll need to replace it but I would like to know what the most likely parts I'll have to replace. Thank you for any help you can give me. If the previous owner rebuilt the carb without a manual he is either lying cos he wanted to keep the maual? Or more likely he gave it a quick wipe and away you go. Much as i don't really feel qualified to disagree with blackhat,especially over 400's having had duff seals on my 175 i would have a check on the carb first. Duff crank seals would make it a real bitch to start and the idle gradually goes up. As you are sat at the lights sometimes. No, much as it could be the seals i'd get the carb properly checked first. Link to comment Share on other sites More sharing options...
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