Hi
Need some help I have an RZ254 that was suberb , that I changed for a Kit pro Limited 30RZ head.

Ather many times in working with length pipe and propellers , can t guet performance and just running.....nothing compare with RZ254 head.
Can someone adivise me with timing or other problem ???
Best Regards
David

I have two S-K30's one is stock and the other is a Motorheads RC modified engine. The stock engine does not rev very good and seems a bit flat on power. The mod engine however is a powerhouse! I have herd from a lot of guys saying the same thing about the stock K-30 not making high rpm horsepower. I hope Scott chimes in on this thread because he knows the plus and minuses of these engines better than anyone.

Was just watching hoping for others input
The K30 design while having so many publicized plus's in design has sadly like much of RCMK's history fallen short of being ideal as delivered to us the consumer.

K30's have very limited transfer passage area in spite of the visual size of the outlet ports on cylinder feeding top end.
Exhaust port duration not bad, but area too little.

Just like YEARS PAST of the Zenoah 231 & 260 using the same casting .... Bigger the bore, smaller the transfer passages become. The k30 has a new casting, but the foot print on cases is the same as the smaller displacement 254's feeding a larger displacement top end. Without some major massaging to get greater bulk flow from crankcase into top end the engine will struggle making high rpm horse power.

But do wrap your mind around the fact it's not just MORE volume moving threw the ports/passages, but also while modifing keeping symmetrical flow going the right dirrection as well.

Have any solutions?? Or I change for the Rz 254 head again??
Big stress ,low RPMs...........
Thanks

If your 254 ran better than the K-30 I would run it. If it was my engine I would get the K-30 modified so it can make more power at the higher revs. The 254 also performs very well when properly modified and tuned.

Iv ran both both stock K30 topkit on S254 bottom end and was ok but struggled to get high end rpms and power so i did some research and decided to to do some mods and new parts need were ordered
1mm stroker and bigbore carb plus gaskets etc
1st job was to strip down the engine and match the transfers from case to top jug,added the 1mm stoker,next matched the bigbore iso block the inlet port with out touching cylinder edge.set the squish and jeez i did make a massive difference.loads more power and better throttle response and high rpms
Hope this helps