XT250 intake port features, grind out or not?


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Tromsoe, Norway
I am now working a bit on the XT250 head, and found a couple of things I wonder what to do with (or leave as is.
One is a notch from a cutting tool, towards cylinder centre, approx 1- 1.5 mm deep, 10 mm long, crescent shaped. See first attached picture.
Then there is a step between the intake port and the last 4 mm before the valve seat, maybe 1-1.5 mm high, for about 130-140 degrees of the seat circumference, basically from 4:30 to 9'o clock on the second picture. The third pic just shows the valve seat, and the amount of aluminium behind it where said step is found.
The last two pics show the same step viewed from the carb end of the intake port.
What to do? Leave well alone, or grind at least a little bit?


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The way I see it, it's downstream of and shadowed by the guide. So there's always gonna be a bit of turbulence there. Leaving it won't have much of an affect because of the turbulence.

On the other hand, removing it prolly won't have much of an affect either.

Loads of help, ain't I.... :sneaky:
Imho you can go wider on the SSR and cut a hint deeper behind the valve guide boss where the mark of the plunge cutter is.
You might want to make the inner diameter of the bowl as big as the throat diameter (0,87-0,87 depending on used cam duration and lift).
Or you might even want to make it a hint larger around its side.

Kind greetings Christian