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Touching up cylinder ports


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Messing with my little 440 motor lately and I'm wondering if it's worth touching the ports at all.  I'm not looking to change the shape of them or alter them very much.  But I notice on the main intake port that there is a ridge on the bottom right where the port meets the bore.  And some other casting junk and stuff that could be polished.  Main thing that I noticed with my fingers is that bump on the bottom of the intake port at the end.  If I have the cylinders off, should I bother smoothing that out or is it best to leave it alone.  The ridge seems like it would be creating some amount of turbulence, or is that a good thing there?

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you can absolutely touch them all up, and make some gains in the process. basically you just want to blueprint them. measure them all, find whichever port is the largest, highest or however you want to call it, and bring the other up to match that.

take off any ugly casting imperfections, smooth the rough edges and finish, blend corners and other places that are clearly restrictions to air flow. and finally, gasket match everything.

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11 hours ago, Tommcat said:

you can absolutely touch them all up, and make some gains in the process. basically you just want to blueprint them. measure them all, find whichever port is the largest, highest or however you want to call it, and bring the other up to match that.

take off any ugly casting imperfections, smooth the rough edges and finish, blend corners and other places that are clearly restrictions to air flow. and finally, gasket match everything.

That sounds good and gives me some reassurance, so thanks.  I've done mild porting on 4 stroke stuff but am a little more nervous with 2 stroke especially around the cylinder bore for timing purposes.  One guy on FB messaged me and said he raced them and had good results trimming both sides of the piston skirts but he didn't remember how much, I don't think I'll be doing that. He said he also trimmed down the fan and I don't think I don't really like that plan either, he raced snocross so probably pretty short races.

I'm looking forward to touching up the ports though and measuring them is a good plan I think, at least what I can measure.  The transfer port bend seems like it might be a tight spot but that seems hard to get at.

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On 8/16/2021 at 11:08 PM, mnstang said:

That sounds good and gives me some reassurance, so thanks.  I've done mild porting on 4 stroke stuff but am a little more nervous with 2 stroke especially around the cylinder bore for timing purposes.  One guy on FB messaged me and said he raced them and had good results trimming both sides of the piston skirts but he didn't remember how much, I don't think I'll be doing that. He said he also trimmed down the fan and I don't think I don't really like that plan either, he raced snocross so probably pretty short races.

I'm looking forward to touching up the ports though and measuring them is a good plan I think, at least what I can measure.  The transfer port bend seems like it might be a tight spot but that seems hard to get at.

my only warning is to be careful with the porting tools, dont nick the nic

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