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mcman56

TY175 Delayed Idle Return

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I have a TY175 that has a delay before returning to a slow idle.  When cutting the throttle, it will stay at a high idle for 3 to 5 seconds before returning to a slow idle.  Just guessing... but if a slow idle is 800 rpm, the fast is maybe 1300.  Besides that it runs fine.  Is that normal or to be expected?  I have cleaned the carb multiple times, checked the reeds and gone from a 30 to 32 and then 35 pilot jet but it is much the same.  I tried spraying WD40 all around the intake system to see if there was a leak.  It is mostly stock with dual stage reeds, fmf muffler and a little weight removed from the flywheel.  Is there something else to look for?  IIRC 4 strokes can do this when rich and 2 strokes when lean.  Is that correct?      

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Could indicate air ingress and if so, most likely the magneto side crank seal.

Could also indicate a sticky throttle cable or slide.

In neutral the revs should go straight to idle RPM when the twistgrip is released.

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First thing is to replace the O rings in the carburettor float bowl, you will see them when you remove the float bowl. 

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Can the magneto side seal be replaced form the outside?  Are there any tricks or advice?  I did replace all of the seals in the carb.  Someone sells a kit.  

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We have exactly the same problem, crank seals replaced cable free and same fault with two different carbs one sonically cleaned with new seals the other off a working bike. New reeds & as yourself tested for leaks.

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I read that a lean needle can cause this so I looked at the carb again.  The needle did have a very slight amount of up and down play in the slide, maybe 0.010 inches.  I have not seen this on other carbs but don't know that I would notice.   I raised the needle one position to full rich and added a small spacer on top of the clip to get rid of the play.  The hanging idle seems gone or at least greatly reduced.      

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The raised needle masked the problem for just one ride.  I pulled the point plate and it is quite dirty near the seal but not really wet.  

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