From: dehahn@strokr.shr.dec.com (chris dehahn)
Subject: Re: Rivera 4 valve heads
Reply-To: dehahn@strokr.shr.dec.com
Organization: Digital Equipment Corporation
Date: Fri, 13 Nov 1992 13:58:10 GMT

--
In article <1992Nov12.224645.6972@research.nj.nec.com>,
behanna@phoenix.syl.nj.nec.com (Chris BeHanna) writes:
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|>From: behanna@phoenix.syl.nj.nec.com (Chris BeHanna)
|>Subject: Re: Rivera 4 valve heads
|>Message-ID: <1992Nov12.224645.6972@research.nj.nec.com>
|>Sender: news@research.nj.nec.com
|>Organization: NEC Systems Laboratory, Inc.
|>References: <1992Nov9.210904.18631@engage.pko.dec.com>
|><1992Nov10.031549.15344@research.nj.nec.com>
|><1992Nov12.145811.25694@ryn.mro4.dec.com>
|>Date: Thu, 12 Nov 92 22:46:45 GMT
|>Lines: 33
|>
|>In article <1992Nov12.145811.25694@ryn.mro4.dec.com> dehahn@strokr.shr.dec.com
|>writes:
|>>--
|>>In article <1992Nov10.031549.15344@research.nj.nec.com>,
|>>behanna@phoenix.syl.nj.nec.com (Chris BeHanna) writes:
|>>|>	7000 rpm with 4.75" stroke = 5500+ fpm piston speed.
|>>|>	8000 rpm with 4.75" stroke = 6300+ fpm piston speed.
|>>|>
|>>|>	How in the hell do you hold that motor together?  Most designs
|>>|>that have reliability in mind (even Japanese motors that rev to 14000 rpm)
|>>|>do not exceed 4500 fpm.
|>>|>
|>>|>that engine awfully damn fast, especially considering the mass of
|>>|>the reciprocating parts.
|>>|>
|>>|>Inquiring (and maybe a bit jealous :-) minds,
|>>
|>>Yes, 4 3/4" stroke by 3 5./8" bore. The flywheel assembly is significantly
|>>lighter than stock.
|>
|>	The _flywheels_ are lighter than stock.  I'm more interested in
|>the masses of the _reciprocating_ parts.  The rapid duty cycle and large
|>load on the bearings of a stroker at over 6000rpm must be tremendous, and,
|>from what I've heard, the thing to watch out for with a stroker is the
|>bottom end, as it can be trivial to scatter the cases all over the road.
|>
|>	Whatchoo got in there?
|>
|>Later,
|>-- 
|>Chris BeHanna	DoD# 114  KotHLF  1983 H-D FXWG Wide Glide - Jubilee's Red Lady
|>behanna@syl.nj.nec.com	          1975 CB360T - Baby Bike
|>
|>Disclaimer:  Now why would NEC agree with any of this anyway?
|>

I don't know where this FUD gets generated. The Shovelhead bottom end
is extremely strong, practically bulletproof. Even with the stock cases. 
Of course, the more material you take out, the weaker it becomes. I
wouldn't build a Shovelhead stroker with larger than a 3 5/8" bore on
stock cases. That's what aftermarket cases are for. Many people have, 
and are still riding them, though, so it can be done.

Now if you drop it into first gear at 100 mph and dump the clutch, I'd
expect scattering to occur.

As for reciprocating parts, the wheels and rods are stronger and 
weigh less than stock parts. So are the pushrods. The pistons are
stronger but I don't know about the weight. The wrist pins are slightly
heavier. The Teflon buttons may be heavier. See how ridiculous this
is getting? 

There is a point where theory becomes irrelevant to practice.

Check with me in another four years and I'll let you know if I've
scattered my mottom end.

CdH

<<<<<<<<<<<<   Ninety eight....don't be late  >>>>>>>>>>>>
Chris deHahn....CdH....Digital Equipment Shrewsbury MA USA
dehahn@strokr.shr.dec.com
Newsgroups: rec.motorcycles.harley