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kelseyds
04-17-2003, 09:55 PM
I need some advice. I own a 99' RS 250 that was a gray market street bike converted to a race bike. I bought it used and before my first race I took the top end apart to see how things looked after 1300 miles. Besides the exaggerated wear on the pistons and rings I found lots of small cavities in the cylinder walls. I took some photos of these but cant figure out how to post them so here is a link to my yahoo briefcase where the photos reside. Warning they are HUGE but the high res is required to see the cavities.

photos.yahoo.com/bc/redri...yahoo.com/ (http://photos.yahoo.com/bc/redrider9112002/lst?.dir=/Rs+250&.src=ph&.order=&.view=t&.done=http%3a//photos.yahoo.com/)


After showing these to a number of "experts" everyone has agreed that this is a result of poor casting. I agree especially since the same cavities can be seen in the water jacket and on other parts of the casting other than the cylinder walls. All my previous experience has been with 4 stokes engines where they either use a cast iron sleeve or some other type of protection in the cylinder.

Has anyone else seen these types of cavities before? Do you think this is the reason for my premature wear on the pistons and rings? Do you think I should approach Aprilia regarding this? Does anyone know who or how to approach Apilia for this?

Many thanks in advance
Andrew Slagle

wsmc667
04-18-2003, 12:29 AM
i think one of mine looked something like that. maybe not as bad. i didn't really think anything of it. if you'r eworried about wear on the pistons, look for vertical lines on the piston that aligns with the holes. (i doubt there are any)

how many miles have you got on the pistons? how much time spent over 11k rpm? over 12k rpm?

good luck,
chris

kelseyds
04-18-2003, 08:24 AM
There are wear marks on the pistons that align with the cavities in the cylinder walls. There are also vertical wear marks on the cylinder walls that start or end with one of the cavities. There was 1300 miles on the engine when I took it appart. I have no idea if these were the original pistons, nor do I know how the engine was treated prior to me buying it used.

Thanks for the feedback
Andrew

micah apriliaforum com
04-18-2003, 08:42 AM
This is how almost all RS250 cylinders look....the little holes just hold a bit of oil....ha ha...They are casting flaws and plating flaws but nothing to be concerned about.