The T20 Suzuki Noticeboard and Discussion Forum: Holed piston

The T20 Suzuki Noticeboard and Discussion Forum Advice, help, chat, whatever! Holed piston

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Mark W

Posted on Tuesday, August 23, 2005 - 10:54 am:

Hi all
I holed a piston this morning and whilst I have arranged a replacement qickly I do not want it to happen again. The other piston (right) looks fine and makes me think that the airboot is ok. Therefore I need to look at the carbs. I can work with the mechanicals but don't know much about carbs. What are the recommended settings for all of the various screws etc on a standard carb? What else should I look for. I only have about 1000km up since the rebuild. Thanks for all advice.
Mark

Adrian

Posted on Thursday, August 25, 2005 - 9:15 pm:

Holed pistons are caused by overheating of the piston crown. Causes of this are numerous, but the most comon are:

- Ignition timing out
- Too hot a plug
- Main jet too small
- Air leak on the induction side

I would check the plug type first, but more importantly check the timing on both cylinders with a dial guage. (obviously look for air leaks too)

Did the piston hole when flat out? Full throttle at max revs, full throttle accelerating? Half throttle? Was the engine 'pinking' or 'knocking'?

Also, check the cylinder head for cracks (rare)

Let me know.

mark w

Posted on Saturday, August 27, 2005 - 10:46 am:

Fixed the piston in the car park at work. Concerned with the amount of schrapnel in the crank cavity and cleaned it up as much as possible - new oil etc - but I see an engine strip in my near future. The carb was obviously out as I now have two cylinders working well and it is a different bike. Cleaned the carbs and sealed all possible air entry points. Seemed to have worked and i am learning about carbs. my bike

Adrian

Posted on Saturday, August 27, 2005 - 6:47 pm:

Nice bike - thanks for posting the picture.
Glad to hear that it is running well know

Anonymous

Posted on Saturday, September 03, 2005 - 9:42 am:

It might have been wiser to open the engine to clean up the crankshaft and gearbox carefully. The debris is poison for bearings and seals. My bike had a similar case, with the same remedy you did, new piston etc... The money spent on a recent crank rebuilt was doubled very soon after the incident.

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