After some expert help!
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@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
wrote on 12 Sept 2017, 23:16 last edited by@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
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wrote on 13 Sept 2017, 08:09 last edited by
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
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wrote on 13 Sept 2017, 08:39 last edited by
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.
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wrote on 13 Sept 2017, 09:39 last edited by
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
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wrote on 13 Sept 2017, 10:07 last edited by
Unlucky man, glad your unharmed though!
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wrote on 13 Sept 2017, 10:36 last edited by
It's like, the signs were there. It didn't fail for no reason.
You see it all the time where people drive their engines to literal death when the bike was telling them it needed investigating.
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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
wrote on 13 Sept 2017, 10:50 last edited by@mightyman dt125r puff of air from top end didn't find any matches for me
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wrote on 13 Sept 2017, 10:56 last edited by ricky0115
It's not seized, managed to get it in the garage there's a hole in the piston and some scrapes on the barrel, they advised a full rebuild so I've gone with it. At least it will be done properly and will be under parts warranty!
There goes my new fat bars & koso digital instruments till next month
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It's not seized, managed to get it in the garage there's a hole in the piston and some scrapes on the barrel, they advised a full rebuild so I've gone with it. At least it will be done properly and will be under parts warranty!
There goes my new fat bars & koso digital instruments till next month
wrote on 13 Sept 2017, 11:33 last edited by@ricky0115 And I refer you to my initial prognosis of the problem...
Who have you taken it to to rebuild it?
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@ricky0115 And I refer you to my initial prognosis of the problem...
Who have you taken it to to rebuild it?
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wrote on 13 Sept 2017, 12:29 last edited by
@ricky0115 Yeah nice. I only ask because these engines MUST (and I can't stress that enough) be built using either genuine or Athena head gasket.
If they use anything else then it absolutely will blow the head gasket.
But if they're a genuine Yamaha Dealer then they should be using genuine gasket.
What piston are you going for?
A hole being burnt through the piston is a big sign of the bike being incorrectly jetted.
You've effective welded through the piston.
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wrote on 13 Sept 2017, 13:09 last edited by ricky0115
I have gone for the wossner? It's was about £70, it's a genuine Yamaha gasket, so the bore will be standard again I guess?
I have only had the bike about 2 weeks and I'm new to 2 strokes so I wouldn't have been aware of any jetting issues so I'll make sure it's up to scratch when I get it back! I know it has a 240 main jet but that's about it.
Thanks for your help!
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I have gone for the wossner? It's was about £70, it's a genuine Yamaha gasket, so the bore will be standard again I guess?
I have only had the bike about 2 weeks and I'm new to 2 strokes so I wouldn't have been aware of any jetting issues so I'll make sure it's up to scratch when I get it back! I know it has a 240 main jet but that's about it.
Thanks for your help!
wrote on 13 Sept 2017, 14:02 last edited by@ricky0115 Yeah nice. I read on PJME that Wossner were having their parts made in China, but I have Wossners in mine so it's fine.
Could be the wrong plug bud, too hot.
I would be very inclined to getting a new plug for it as well.
It might not be standard size if you have damaged the bore, it'll require a rebore.
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wrote on 13 Sept 2017, 14:46 last edited by
Fair enough, it's the plug recommended in the Haynes manual NGK BR9ES, not sure if the gap was wrong maybe? They do an iridium plug also if they're any better?
Any tips on running it in? Is there any way to limit the throttle as my rpm counter doesn't work.
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Fair enough, it's the plug recommended in the Haynes manual NGK BR9ES, not sure if the gap was wrong maybe? They do an iridium plug also if they're any better?
Any tips on running it in? Is there any way to limit the throttle as my rpm counter doesn't work.
wrote on 13 Sept 2017, 14:48 last edited by@ricky0115 Shouldn't worry about revs, it's more load if anything.
Just bed the engine in gently or 100 miles. And vary the throttle after that.
It's all about trying not to glaze the rings and cylinder walls.
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wrote on 13 Sept 2017, 17:08 last edited by
That's me told! Spot on Calum!
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@ricky0115 Shouldn't worry about revs, it's more load if anything.
Just bed the engine in gently or 100 miles. And vary the throttle after that.
It's all about trying not to glaze the rings and cylinder walls.