After some expert help!

  • So I picked up a 98' DTR and have been riding around for about a week with no issues, I was out the other night went to my mates and when I came to kick it back up, nothing. I ended up bumping it and it rode fine until I stopped at the lights I let the revs off and it cut out, tried to kick it whilst it was warm, nothing. Pushed it home. Next morning tried a new spark plug, took the carb off checked no jets were blocked and it seemed immaculate inside put it back and it kicked up first time and is blowing out more smoke than usual so I let it run for abit to burn what ever was smoking and it bogged out again. Now it will not start unless bumped, it runs very hot and blows a shit load of smoke out the exhaust! Also when I turn on the fuel it's trickling and bubbling out of the carb overflow? Assuming the needle is trapped or there is an air leak?

  • Administrator

    You haven't by any chance left the choke on have you.

    I remember when I first got my DTRE I had this exact same issue. Would start fine from cold, forgot I left the choke on, then ride around it wouldn't idle. Once it died it simply wouldn't start.

    That would be my first place to look.

    Was the carb leaking before or after you dismantled it.

  • I may have left the choke on yes, as I came from a WR I maybe forgot to turn it off. I'm not sure if it was leaking before or not although whenever I would take it out the garage in a morning it stunk of petrol so could possibly of been leaking before. What damage could leaving the choke on cause?

    Thanks for your reply!

  • Try to take spark plug off and bump it a few meters . Put spark plug back and should be ok. Happened to me few times .

  • How do you mean? just run with it in gear?

  • Administrator

    @ricky0115 No damage, it can cause bore wash but I doubt there will be any problems here.

    Choke on to start, then once the revs die down, take the choke off and that's it.

  • Thanks I will give it a go.

    Any idea on the carb overflow? Tried tapping the float end in case it was jammed but no luck. Thinking about taking it to a garage and having all the seals replaced. Noticed a threaded bolt on the reed block, would this cause an air leak?

  • Okay so I just tried kicking it up and on the third kick I heard a puff of air like a blow off valve letting out pressure but I'm unsure where it came from it sounded like it was somewhere near the carb or air filter

  • Administrator

    @ricky0115 Probably tried to fire up but failed.

    You haven't blown a hole through the piston have you? It does start right?

  • @Calum It will only start from bumping it, I'm going to take it to the garage on thursday so I will update with the issue.

  • Global Moderator

    A couple of my bikes used to occasionally make that sound when I was kicking them. I'm sure it only happens on an engine that isn't perfectly set up / running little bit lean or little bit rich? Either way the bikes ran okay.

  • @mightyman I've only known 4 strokes to make that sound

  • I'd say piston rings at a guess maybe just a cracked ring would cause issues

  • @andrewj1680 thanks

  • @declan I think it's drawing in way too much air, everything is standard air intake wise. How can I find the piston size I know it's been bored out but I'm unsure of the size

  • @ricky0115 markings on top of the piston should give you the size or measure the bore with calipers, either way it's the head off, not a big deal. Personally think your problem lies elsewhere but expect to be proved wrong, see what the garage says, hopefully something simple. Good luck

  • Global Moderator

    Just had a quick Google and first couple of results suggest worn rings / not correctly sized piston, which makes perfect sense because the sound will be the air squeezing through the ring seal when compression is happening.

    I suppose this means my bikes could have been a bit down on power not having a correctly sized piston 😂

  • I've had this before on a high mileage DT125R and due to being poor I left it with dire consequences. Basically the piston tried to make its way out via the exhaust port. I went from a standard bore to 2.00mm oversize in one go which made me cry when I realised.

  • Yeah I just tried to ride to work and the engine died doing 60 the back wheel locked up I have never been so scared in my life! I think it's ready for a new top end! Actually anyone selling a wr200 engine?😂

    Cheers guys

  • Global Moderator

    Unlucky man, glad your unharmed though!


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