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Clubroom => Tech Talk => Topic started by: Vince H on February 20, 2015, 05:32:34 pm

Title: Yamaha DT175C blows white smoke
Post by: Vince H on February 20, 2015, 05:32:34 pm
hi my dt175 is blowing a heap of white smoke out the exhaust can anyone tell me reasons why?????
Title: Re: Yamaha DT175C blows white smoke
Post by: sleepy on February 20, 2015, 06:25:12 pm
How long has it been doing it for? When is it doing it? Is it getting worse?
Could be sucking in gearbox oil.
Title: Re: Yamaha DT175C blows white smoke
Post by: pokey on February 20, 2015, 07:02:09 pm
How did you get it to do that neat trick?
Stinks a bit aswell?
  Gearbox lube for sure. Could be centre gasket or main seals but either way its not going to be a fun job
Title: Re: Yamaha DT175C blows white smoke
Post by: David Lahey on February 20, 2015, 09:58:18 pm
not much info on the history of the motor to go on but here is one about those motors that may not be common knowledge:

there is meant to be an o ring at the spacer behind the primary gear on the crank. If you motor has just been worked on, and that o ring wasn't replaced, that might be where the gearbox oil is getting in. It's an odd size o ring and some people leave it out or use the old one
Title: Re: Yamaha DT175C blows white smoke
Post by: yamaico on February 21, 2015, 07:41:57 am
Couple of tests to determine whether it's the seal:
Has the gearbox oil level gone down?
When the bike is running lay it over to the left hand side to let the gearbox oil away from the seal. If the seal is bad the smoking will stop and it should start to suck air and run a little lean.
As David says, that o ring is critical, but even if it's the seal it's an easy repair.
Title: Re: Yamaha DT175C blows white smoke
Post by: TT5 Matt on February 22, 2015, 01:54:29 am
buy the old girl a seal kit and some outer cover gaskets as if there factory fitted seals still in it they would be hard and starting to develope cracks
Title: Re: Yamaha DT175C blows white smoke
Post by: bazza on February 22, 2015, 07:09:38 am
As Yamaico said