Hi All Again!
Just got some new +040 pistons from the club shop, my old ones had valve cutaways but the new ones don't? I've got a 4S cam fitted, will there be clearance issues?
Cheers
Paul
Thanks once again Stan! I…
Thanks once again Stan!
I've bitten the bullet & purchased a Full Auto head from AN, because of problems with my head.
Yes please to the info sheet.
Do you want to send by email?
Cheers
Paul
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Got those thanks Stan, I'm…
Got those thanks Stan, I'm getting the new pistons modded as per the old ones.
The bike came to me as a PR Rep from my brother with the Pr tank/fairing etc, Rita ign with 4S advance curve, Hemmings big head valves & 4 S cam, all I'm doing is changing back to std roadster as my back/neck can't deal with the head down, arse up riding position. I felt it always run well, however, maybe not as much low down grunt as it should have? I don't know because I've always had my T150!
Cheers
Paul
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Yes!
Let me expand on that...
It is almost certain that the head has been skimmed to increase compression - otherwise it'll go slower than standard with a 4S. So not just more valve lift but they're closer to the piston to start with. After cutting the valve pockets be sure to check everything clears by putting some plasticine or similar in the pockets and measure the thickness after tunring the engine over. Yes, you'll put the engine together and take it apart several times.
I have the tuning sheet for the 4S that gives machining specifications for the valve pockets if you would like a copy.