[2-stroke demon]

Just curious about the port matching on my cylinder, I have possession of my cylinder right now so I can drop it off to get a new bore done... I sat around last night for an hour looking at and studying my pro-x 350 that was re-sleeved and was curious as to how well the sleeve should match the ports on the cylinder once being port matched? I was under the impression that the sleeve would be matched to the ports so that the transfer between the two areas would be flushed 100%. On my cylinder there are multiple areas that the sleeve overhangs the cylinders ports... Wouldn't this cause turbulance?

 

[rsss396]

yes it will cause some turbulence affecting flow, will it be a night and day difference? no but non the less a difference.
The transfer ports also should blend nicely its all the little things that can add up to a better running motor but like I said you will hardly know the difference as long as all the port openings are at the same heights.

 

[2-stroke demon]

Cool, thanks

 

[acecarlos]

Just curious about the port matching on my cylinder, I have possession of my cylinder right now so I can drop it off to get a new bore done... I sat around last night for an hour looking at and studying my pro-x 350 that was re-sleeved and was curious as to how well the sleeve should match the ports on the cylinder once being port matched? I was under the impression that the sleeve would be matched to the ports so that the transfer between the two areas would be flushed 100%. On my cylinder there are multiple areas that the sleeve overhangs the cylinders ports... Wouldn't this cause turbulance?
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Let’s remember the reason your cylinder was re-sleeved was the multiple cracks in the sleeve, specifically between the exhaust and exhaust auxiliary ports, exhaust centerbridge and the rear intake, boost web to intake transfer windows, right & left. Once the sleeve was removed, we found two additional cracks in the cylinder casting across the intake windows to center Boost track.

All of the original cracks to both the sleeve & casting occurred because the original porting on the cylinder ground most or all of the sleeve & casting support vertical webs (casting & sleeve material between port windows), leaving the sleeve & casting with little support and strength.

After welding your cylinder casting up to create material & add strength (that we did NOT charge you for), we re-sleeved and ‘port matched’ to the casting within reason, we left extra sleeve material in all areas that had previously cracked. If we would have ground the sleeve to match the super thin casting webs , you would of likely developed cracks once again as the sections would have been once again ultra-thin.

A good example of how thin and week your original sleeve & casting had been ported to, is seen in your pictures. The cylinder casting had been ported & ground to far as can be seen in the pictures, further grinding the sleeve to match the thin casting would of left very thin webs between the auxiliary exhaust ports & main exhaust port, as well as very thin web sections between the intake boost to auxiliary intake ports (right & left), and the center exhaust bridge.

Back to the original question: Is this all there is to port matching? NO…when dealing with cylinders that failed or developed cracks, there is a lot more to it than meets the eye…

PS: I am more concerned for you in that you once again get your cylinder properly bored, honed with proper port radius, with a proper engine asembly and full leak down test...if you need any info, just give us a call.

Carlos

 

[2-stroke demon]

Thanks carlos, just curiosity... I learn as I go, I know what your talking about as far as the cylinder casting material being very thin... I dropped the cylinder and new piston off this morning at local atv shop that is doing the new bore/hone/port radius... Owners personal bike is a trx250r and has been riding them his entire life... Anything I should look for as far as how the port radius should be done

 

[acecarlos]

Port radius for a 250R is a minimum of .5MM x 1MM..that being 1MM in the horizontal direction across the ports and .5MM in the vertical direction up/down the webs. 99% of builders do not radiuss to these numbers as it creates a lot more work to blend 'real radius' from vertical to horizontal. For us, even do we do this every day; it take 45-60 minutes of work to grind and hand blend all the port windows to .5MM Vertical x 1MM Horiontal.

Remember these are 'radius' edges, and NOT as commomnly known as or called port 'chamfers'...big difference.

Carlos

 

[threewheelin-feelin]

old tread.. but is it ok to run a cylinder like this? i just got a stock 250r cylinder resleeved and didnt want any port work done so my sleeve is over hanging in a few places...not worried about small amount of performance lose..i have a 310r im building for performance..just want to make sure it will run correct like this

 

[acecarlos]

Yes it's "OK" to run as is...noting performance will be lost, more than "a small amount", however; no damage should occur.

Carlos