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Crankcase transfer ports too large

Posted:
Thu Mar 23, 2023 9:24 pm
by Mr Dave B
Hello folks.
Please can someone help.
Will a standard SIL stage 4 200cc barrel, piston and head work on crankcase that has had the transfer ports opened for a 225 TS1 barrel.
Will I need to open the barrel spigot and blend the barrel base transfer area to the crankcase.
Thanks lads.
Re: Crankcase transfer ports too large

Posted:
Fri Mar 24, 2023 10:14 am
by hullygully
wouldn't harm it too bull nose them in the barrel
Re: Crankcase transfer ports too large

Posted:
Sat Mar 25, 2023 5:06 pm
by Adam_Winstone
You can do but I have a suspicion that it'll make no difference, as per Darrell Taylor's 'waste of time and effort' feature in Scootering.
Re: Crankcase transfer ports too large

Posted:
Sat Mar 25, 2023 10:36 pm
by Knowledge
I agree Adam.
At the bottom of the transfers the fresh charge has little velocity from the pumping action of the primary compression ratio. It is only when the mixture is actually in the transfer ducts that it obtains some speed and, as importantly, some direction.
In a tuned engine, when things really need to get going, the negative pressure phase of the expansion will do more work than the primary compression anyway and will suck the fresh charge up the transfers regardless of minor obstructions at the base of the barrel.
So don’t worry Dave B.
Re: Crankcase transfer ports too large

Posted:
Mon Mar 27, 2023 11:55 am
by Mr Dave B
Thank you for your help chaps. Very much appreciated.