1/2/3 Angle Valves? Race Questions............ - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 4 (permalink) Old 05-13-2015, 03:53 AM Thread Starter
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1/2/3 Angle Valves? Race Questions............

So, what is the valve/seat angles or RC's and what is the valve/seat angles on race and/or HRC valves/seats?

Are HRC/Race valves more undercut than stock?

What specifically fails in RC valve train in high rpm engines? Valves themselves, springs or keepers etc?

Where other than Moriwaki where can someone get TRUE race cams for an RC build?

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post #2 of 4 (permalink) Old 05-13-2015, 06:56 PM
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kent cams via Roger Ditchfield (revolution) in the UK...complete set....retainers, springs, cams, slotted cams wheels....MAKE SURE YOU HAVE A SHOP THAT KNOWS WHAT THE FCK THEY ARE DOING TO INSTALL/DEGREE THEM!!!!

exchange rate is great right now so it's time to do it..
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post #3 of 4 (permalink) Old 05-13-2015, 09:26 PM
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If you push an OEM valve train to higher RPMs, the valve springs will start to resonate at a certain frequency, which can then lift the spring off its seat with the valve train no longer following the cam profile.
The valve then abnormally stays open longer than required and is smacked by the upward rising piston crown.

This can lead to a damaged/broken piston crown, and bent/destroyed valve(s).
Depending on the severity, it can be bent valves and slightly damaged piston, to total catastrophic engine failure.

Eliminating valve spring harmonics and breakage was the reason why the desmodromic valve train was used by Mercedes race cars in the 50's (Ducati did not invent the desmo valve train).

In modern times, pneumatic valve springs were developed for use in F1 and later during the modern MotoGP 4-stroke bikes.
The steel springs are replaced with pressurized nitrogen to act as valve springs.

Not only was the valve train able to work up to 20,000 RPM, but the cylinder head temp was cooler, as a substantial part of heat build up in the head was from the steel valve springs twisting and relaxing during operation.
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post #4 of 4 (permalink) Old 05-13-2015, 10:55 PM
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Very interesting as always Sub.
Another thing about F1 engines is they have very, very short strokes - hence why they are able to scream at such high rpm, as otherwise piston speeds would be too high for reliability in a race. I was shown an F1 piston a few years ago and told what the stroke was, can't remember the exact figure, but somewhere around 20mm stroke for the engine that particular piston had come from. Amazing stuff.

I looked into it and after seeing what race engine builders had to say, I thought better not to build a more powerful SP2 engine for mine.
Reliability tends to suffer as a result and I don't want to be doing that kind of maintenance.

Euro RC51 SP2: HRC WSB Ti Hi-Level, T1 Airbox & Snorkel, PCIII, Dymag CA5 Carbon Wheels, Ti64 Spindles (F, R & Swing Arm), Mori Link, Maxton GP7 Shock & Ohlins 832 Forks, Brembo GP Calipers & SBK narrow track (F), Braketech Disc (R), Brembo billet Underslung x 2 Brembo RCS, Tyga Triple, 7075 Stem, Probolt Titanium all over, Babyface rearsets, MR Complete Carbon Lineup, Custom Undertail & CBR 1000 LED, Watsen LED Indicators, Harris Brace, Giles clip-ons, Corbin seat, etc. 2013 BOTY.
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