i am familiar with tweekin full size engines and was wondering if anybody has tried knife edging the con rod then balancing the rod against the crank weight?
Also porting on the piston sleeve any advice on this?
is there any benifit to port conditioning and tear dropping the feed hole through the crankshaft?
is ther any benifit to polishing the carb venturi?
and the last questioon is about compression. so if you remove a head shim you have to run a higher % nitro or is it the other way around?
i am running a hpi T15 i like it just wanna get a bit more out of it.

nobody is tweakin engines yet?[&o]

I know there's a few guys around my track that have had work done on their engines by some guy. Basically, the knife edging of the rod, and balancing of the internals, is usually already done at the factory on higher performance engines. They also already have extensive port work done, like the 5 port Rhody version of the RB 12. There was a recent article in one of my nitro mags that described "homegrown mods" Basically, it's like playing with fire. You could do more harm than good if you're not familiar with the techniques involved in getting more out of these engines. Alot of times, all they do is a little port work. I doubt polishing the venturi would hurt...

Usually if you mess with them you will end up doing more harm than good. These engines are so small that if you remove any material from the inside of the case you will lose crankcase pressure resulting in poor performance. A little polishing and smoothing of port edges is about the best thing to do. Otherwise getting a high end engine will already have a knife edge rod, flared crank port and proper balancing.

Listen to what gubbs said about just polishing, you don't want to inadvertedly affect the flow in and out...

About your shim question, the higher Nitro you go, the more chamber volume you need to prevent pre-ignition or detonation. Most stock engines (car and truck) will run 20% but not 30%, without an additional head shim or 2....

hey gubbs 3,
have you tried a little back polishing on your booster ports