Bought DT125X, cannot get it to start? Spark, fuel OK
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Okay, I will try it then, but I guess the yamaha service put it in. On the internet I found out that I EG differs only from ES that it is a "racing" type plug with a thinner electrode that is less likely to get fouled. But I will try fresh fuel and Br9es when I have time.
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Got the new stator, still can't bump start it. The only difference is that I inject fuel at the plug, It will try to start for a few strokes. Also got the new plug, BR9ES with 0.6mm gap. Stripped down the carb again, it is clean, and tried it with fresh fuel, still nothing. Intake manifold looks ok, and tried to see inside with flashlight, and membrane looks okay too. If I take out the plug, it is not soaking in fuel, so it is not getting fuel, despite trying to bump it with choke on. I am hopeless now. Compression is okay I think because it is really hard to push even for two people.
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@Lorant2 Is the plug sparking? Take it out, connect it to the HT lead and place the tip against a metal surface. Crank the bike with the kick starter and look for a spark, it will be very visible for a split second. If there's a spark then the plug is getting voltage, if there's nothing then you have an electrical problem.
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@NINJA I cleaned it completely, even removed the atomiser tube to make sure the holes arent blocked. Gaskets are fine it is not leaking and fuel level is correct. Has 17.5 air jet and 220 main jet which might be small considering that it has gianelli but it shouldn't be a problem to start it, especially since it has run with this setup for the previous owner. Power valve servo works as it checks, and it is set to the mark on the cylinder.
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Did you clean the choke passageway in the bowl?
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Also, have a look at the reedvalves for broken or torn reeds.
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I checked the choke and it is not blocked, I blew it eith compressor. I will have a look at the reeds the following day. But I took a picture inside the intake manifold and it looks ok, I will have a look if it has increased gap then I will replace it, they are moving freely as I touched it gently with my hands. I will check if I can see through it, but then again that would cause flooding I think and my plug is not oily at all after bump starting it for meters.
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I cleaned all the earths a week ago when I was diagnosing the starter motor. The earth is clean on the battery, on the engine, on the HT coil and on the regulator too. If I set kill switch to off, then I dont have any spark, neither if I let my side stand down.
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I mean that it works as it is intended. I turn the ignition key to on, power checks, and the kill switch is set to "run" I guess (I think it is pressed from the top to the bottom), anyway it is working as it is written on it. I believe this is not an electrical issue anymore, my plug is just not soaking in fuel and oil as it should despite the (I think) big compression. Tomorrow I will also have a friend to come over and we will check the exact PSI compression, what should be a correct value? Above 100, with full open throttle?
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@Lorant2 OK well it's another issue then. You can download the service manual for free from here;
https://www.manualslib.com/manual/1203458/Yamaha-Dt125re-2005.html
And well worth the money is a Haynes manual;
Both have lots of tips and troubleshooting guides!!!
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Some update:
I have removed everything again, reeds are perfect, intake manifold too. Boost bottle was a little loose so I replaced the clamp on it and it is better now, and managed to start the bike with a catch LOL
I put it in 6. , turn off ignition and bumped it a lot with choke on, then put it in 3. and managed to start it and rev it a little till I dropped the gas and it is not starting again. Also it was smoking a lot but it was revving freely and dropped the rpms nicely too like theres no air leak. I will try to further investigate it.
Also I had the air screw open at only 1/4 turns now. It was on 1 turns before and completely closed when I first disassembled it.
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As fot cleaning the choke, as I said theres a passageway in the floatbowl, thats often overlooked when cleaning carbs, as people focuse on the main body. Im not talking about the choke plunger and where it mounts in the carb.
Just another thing to exclude
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@Jens-Eskildsen I did blow that too. I started it today too and went for a 10km ride. Couldnt get it past 70 kmh. Removed exhaust, and saw that the power valve does not opens despite it is turning on ignition. It was rotated by 180 degrees, I think they installed it incorrectly in the service. Also, found another major problem, one huge piece of the upper piston ring is teared down
So i will have to disassemble the cylinder and replace the rings/get a new piston and rebore. I might be lucky that it tore off the front where only the exhaust port is and it got out. Also it was smoking quite hard while riding and it was working better with choke on. On low rpms it felt as it has air leak, on high rpm it didnt rev I think because of the power valve misfunction.Am I right that only Athena and original head gasket is recommended to use?
And how hard is it to replace the right side crank seal? Does it need removing the whole clutch or just the little cog on the crank? For the left side I have to make a flywheel puller plate as I see.
Also, I currently have 220 MJ and 17,5 Pilot jet, am I right that I should start out with the standard DT125R setup 25 pilot jet and 240 main?
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@Lorant2 Sounds like the PV was hitting the piston which would explain a lot of what's going wrong with your bike. I'm glad to hear that it ran eventually, a top end rebuild would eliminate a lot of problems for-sure. And yes Athena or OEM gaskets are the best, personally I feel Athena are the best ones. Check in the manuals I mentioned before to see about replacing those seals. I would do those repairs and anything else which you find faulty whilst fitting those new parts and then see where you are with your bike? Before you go spending lots more money on other parts, which may be OK for now. :winking_face:
