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| Yamaha dt400e http://www.kawi2strokes.com/forum/viewtopic.php?f=11&t=12879 |
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| Author: | greens8 [ Wed Jun 14, 2017 2:08 am ] |
| Post subject: | Yamaha dt400e |
Hi, just done a resto on a 78 dt400e. Full engine rebuild except top end which measures good. Am very familiar with mikuni carbs as I pretty much only do 70s 2 strokes. Bike will start second kick on choke, and fast idle. When I turn off choke engine tries to die, need to throttle up above 2k to stop stalling. Would expect it to be the carb but I have gone over that vm34ss numerous times. Timing seems exact, have gone just either side of the timing mark to test. No difference. Manual says float level 22.9 which of course I have, but +/- 2.5, so have tried all that. No difference. Saw a blog on another site, someone said identical problem, solved by new cdi. Manual cdi test you need special testers, can`t test it or the magneto and rotor. How likely is it to be the magneto as I am thinking the spark is only strong enough when revs are up, not below 2k? I have an opportunity to buy a stator/magneto local for about a ton which is reasonable and a lot quicker than getting from the states, but I am reluctant to just pot shot it. Any suggestions guys? Steve. (Australia). |
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| Author: | rngdng [ Wed Jun 14, 2017 1:22 pm ] |
| Post subject: | Re: Yamaha dt400e |
Hallo mate! My DT400 had some issues, and one of them was the plug cap was causing a miss at high RPM. Not your problem, but something that happens. I would check the pilot jet very closely. With the choke on, the pilot jet is effectively bypassed. Once the choke is released, the pilot jet control idle conditions. If it is even partially clogged, it will cause problems. I know you have already cleaned the carb, but try it one more time. If you used an aftermarket carb kit...that may be your problem as those kits' jets are ALWAYS WRONG. Lane |
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| Author: | greens8 [ Fri Jun 16, 2017 4:20 pm ] |
| Post subject: | Re: Yamaha dt400e |
Yep I know about the inextactness of kit jets, and the pilot jet is 27.5 and totally clean as is the feeder hole. Had carby off maybe 25 times. Another site suggested the plug cap so I`ll go there, thanks. |
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| Author: | 67lotus49 [ Fri Jun 16, 2017 11:38 pm ] |
| Post subject: | Re: Yamaha dt400e |
I have used a strobe timing light to help diagnose a week low speed coil. Just a thought. |
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| Author: | usernameandpassword [ Sat Jul 15, 2017 6:25 pm ] |
| Post subject: | Re: Yamaha dt400e |
27.5 seems like an awful light pilot. If you screw the idle screw all the way in, does it get better at all? If the airbox is disconnected, hook that up. It could be that the air box is restrictive a good bit. The main is a 190 (seems tiny for the displacement) so I'd assume that airbox is restrictive at some point. My 71 rt1 has bigger jets and has a smaller displacement. |
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