Difficult start



  • Hello.

    So today my DT has started to refuse to start when kicked.

    I don't really know that it's of any help, but here is a "video" (just audio really) of me kicking the bike, and it not starting.
    https://www.youtube.com/watch?v=O5aPEnT_FNQ&feature=youtu.be

    • Choke is on (tried with it off aswell, no luck)
    • Bike is warm after a 30min ride

    I had the carb out a couple months ago and cleaned it throughout, bike seemed to run smoother after that.

    When I roll start it with a lot of speed and choke on I can get it going after a few attempts.

    Once running the bike goes reasonably well, the engine seems to rattle a bit, but this has been persistent since I've had it, so nothing new there.

    Any recommnedations for first things to check? I was going to try a new spark plug first.



  • @Uber_Beluga This may sound daft, but do you have any 2T oil in the bottle? Sometimes when it's low the engine refuses to start.



  • @CYBER-NINJA
    Hmm, I'm pretty sure it's topped up, but could be that, I'll check tomorrow morning when I try start it again.



  • @CYBER-NINJA I haven't got a two stroke Oil bottle. There is no parameters for the CDI to not spark if it's low I'm afraid.

    Four things are needed for this to run

    Compression, Ignition, Fuel and oxygen. If it runs and pulls then you've got compression. If the spark plug is wet, then you've got fuel. The only things are suffocated intake system, dirty air filter blocked by leaves and crud. Or the electrical system breaking down. Be it HT leads, Spark Plugs, Pick ups, Coil, weak battery will do it too! CDI could be faulty.

    Way to check electrical is to take the plug out of the head. Rest it against the frame and kick it over. Should see the plug giving off nice and regular sparks.

    Be sure that the correct heat range plug is in there, and that good fuel is used.

    BRE9S BRE8S I believe are the grades you will want.



  • @Calum My reply was based on personal experience, last week I was very low on 2T oil and the bike took like 50 kicks to get it to start. As soon as I topped up the oil it started first time, so I suspected the low oil sensor was stopping the bike from starting? But yeah I agree with your fault diagnosis, you would be surprised how many people have had starting problems with bikes and cars, when it's simply a lack of fluids like oil or petrol, or the immobilizer is not switched off etc.



  • @CYBER-NINJA Yeah sure mate I don't doubt that. However there is no mechanism to my knowledge to kill the ignition on low oil. I suspect it was the cool down period from when you stopped kicking it over and filling up yhe oil that was why it started.

    The amount of times in my day I have tried starting my bikes wit the kill switch off is ridiculous lmao! Sometimes things like that just get overlooked.



  • Same problem thismorning, once again, second attempt at roll starting was succesfull, luckily I roll my bike out to a hill when I leave home!
    Bike got me to my destination and even started first kick after I killed the engine.

    The red engine oil light came on on my way back, I'll wait for things to cool down and check the oil... Logic tells me this is unrelated to my starting problems, but it's a little odd.

    @Calum said in Difficult start:

    Four things are needed for this to run

    Compression, Ignition, Fuel and oxygen. If it runs and pulls then you've got compression. If the spark plug is wet, then you've got fuel. The only things are suffocated intake system, dirty air filter blocked by leaves and crud. Or the electrical system breaking down. Be it HT leads, Spark Plugs, Pick ups, Coil, weak battery will do it too! CDI could be faulty.

    Way to check electrical is to take the plug out of the head. Rest it against the frame and kick it over. Should see the plug giving off nice and regular sparks.

    Be sure that the correct heat range plug is in there, and that good fuel is used.

    BRE9S BRE8S I believe are the grades you will want.

    Thanks for this Calum, very useful! I'll get my tools out and follow this train of thought this weekend. I'll let you know how it goes.

    I'll also just order a new spark plug. This looks about right.
    https://www.amazon.co.uk/Spark-plug-NGK-BR8ES-YAMAHA/dp/B00EK9M87A/ref=sr_1_2?ie=UTF8&qid=1465406511&sr=8-2&keywords=DT+125+re+spark+plug



  • @Uber_Beluga I personally would get iridium. Just me though



  • Like this?: https://www.amazon.co.uk/Spark-plug-NGK-Iridium-BR8EIX/dp/B00ELO18L6/ref=sr_1_5?ie=UTF8&qid=1465406511&sr=8-5&keywords=DT+125+re+spark+plug

    I was going to go for it, but it didn't match the code you gave

    The iridium model is a BR8EIX as opposed to a BR8ES
    Is the same thing in terms of compatability? Presumably the BR8 is the important bit.

    I haven't ordered yet so I can get the iridium one if they're any better.

    EDIT: This explains the NGK plug codes nicely https://www.ngk.de/fileadmin/Dokumente/EN/downloads_not_used_in_download_area/ngk_zuendkerzen_code_en.pdf
    I'll order the iridium model



  • @Uber_Beluga That's the pup.

    The 8 and 9 is heat range. A cooler plug will be better to help stop preigniton but a hotter plug may aid starting.

    Something like that anyway,



  • Have you tried checking your battery? The fact that it's difficult to start when left for a night or so but easy to start when bumping or after a ride suggests to me Atleast that your batter isn't holding charge all that well. And as said a new plug is always a good first step when having trouble, even if it's sparking fine visibly.


  • Global Moderator

    @Burridge said in Difficult start:

    Have you tried checking your battery? The fact that it's difficult to start when left for a night or so but easy to start when bumping or after a ride suggests to me Atleast that your batter isn't holding charge all that well. And as said a new plug is always a good first step when having trouble, even if it's sparking fine visibly.

    Battery wouldn't affect kick starting it.



  • @Burridge I agree weird stuff definitely happens on a low battery, but it should bump no problems.

    The other ones are if it's dependant on the batter and the fuse is a bit iffy, or the holder at least.



  • @Uber_Beluga @Calum My bike came with a BR9ES plug in it, so I just swapped it for a BR9IX this weekend, thinking I was just swapping from a regular plug to an Iridium one. But boy have I noticed the difference! She pulls like an express train now and my previous best top speed was 72MPH, now I can get 78MPH. She still starts first kick 99.9% of the time and climbs up the rev range a lot faster, There is a bit more vibration coming through, so I'm guessing that the iridium part makes for a better spark? AKA a bigger bang, I hope that I'm not gonna do any long term damage??? ;O)



  • @Calum
    8 seems to be recommended heat range for my particular bike, I see it's 9 on some other DTs, seems strange that they would vary.
    I've just ordered one of each heat range so I can try them out. I found them for around 10 pounds each (here and here) so relatively inexpensive in the grand scheme of things.
    A quick google of preignition has me kind of scared of the 9. Even with the tempting attraction of making starting easier I think I'll avoid putting the 9 in if I can.

    @Burridge
    I'll give the battery a check anyway as I have a multimeter, I don't have a working starter motor in the bike at the moment (It's an RE model), but I'm hoping to pick one up when one appears on Ebay so might as well get a new battery if mine is no good.

    EDIT: Just realised the higher the number for the heat range the cooler the plug, I guess I have nothing to worry about with either plug then, worst case scenario it just wont start.



  • Yeah I ran both, preignition is only going to really be an issue if you're getting into the tuning game. I'm sure those will be fine



  • I think I made a little progress with the starting problem today.

    I can confirm that there is no spark from the plug when kick-starting. Any ideas what could be causing no spark? The bike does run when I get it started by roll starting it, so it must spark sometimes.

    I'll have another go next weekend, but any advice on where to start in advance would be appreciated 🙂



  • I've spent more time on the no spark issue today. Got the new battery in and no change, that didn't really surprise me, but I wanted a new battery anyway given that the old one was only giving around 12.3v on a full charge.

    I started going down a list of things to check that I found from this random video on YouTube. (Internet is my only source of knowledge)
    https://www.youtube.com/watch?v=wjvnUIwQ33Y

    First I checked my kill switch, it wasn't good. Full resistance switched on or off. If I caress the switch in just the right way, sometimes it works, but I'd rather not carry my multimetre with me everywhere I go, so off it goes.
    They aren't cheap, so I'm probably going to try and fix the switch, simple enough electrics hopefully.

    Now, question is, should I get a spark with that kill switch pulled from the bike, or will I need to bridge the connections that it plugged into? I didn't try that when I was outside, but thinking retrospectively that's probably what I should have done?

    I went on to check the coil which caused more confusion, but I won't get into that until I've got the switch sorted.



  • @Uber_Beluga Bridge the connection.

    The kill switch contacts have probably corroded. Try spray some electrical contact cleaner in there. Or dismantle it and rub the switch contcts down,



  • Thanks Calum,

    I'll get the switch sorted through the week and have it ready for next weeked to try again.

    I spent about an hour trying to get a spark with that switch off the bike without even thinking that having it off was the same as having it not working. Feeling pretty thick right now.