From: dehahn@strokr.shr.dec.com (chris dehahn)
Subject: Re: Miscellaneous Performance Questions
Reply-To: dehahn@strokr.shr.dec.com
Organization: Digital Equipment Corporation
Date: Mon, 31 Aug 1992 18:38:31 GMT

--

dehahn@strokr.shr.dec.comIn article <1992Aug31.032325.21200@acd4.acd.com>,
mgr@sedv1.acd.com ( Martin Rivers) writes:

|>This is a list of various questions I have regarding performance
|>related items.  Any feedback is appreciated.
|>
|>1.)  What are peoples favorite carbs for performance applications.
|>I've heard good things about Dell 'Orto (nothing bad so far), good and
|>bad about S&S, bad/ho hum about the Harley Screaming Eagle.  Mikuni I
|>see used a bit in bikes featured in various magazines but don't know
|>anyone around were I live using one.  The performance application
|>doesn't include any nitro or alchol (at least today).

The dual choke Dellorto works well on small strokers. It should be fine on
your 88". S&S 'E' carbs are an even better fit.

|>2.) Several months ago I posted a question about the Rivera 4 valve
|>heads.  Anyone try them, know of anyone whose tried them and if so,
|>what are the impressions.  I am about to (gulp) shell out for a set
|>shortly and am looking for any last minute negatives.  These will be
|>going on an 88 inch pair of cylinders (from S&S) (no stroking yet).
|>Rivera is also really pushing the Dell 'Orto carbs, Dyna ignition,
|>coil and RPM limiter so any comments about these components are also
|>welcome.

There are two in my area. There have been numerous problems with the
motor. First, the valve adjusters break and can get sucked into the bottom
end. Seccondly, the valve spring pressures beat the snot out of the starter
and it's not an easy bike to kick start (if you have one). Third, the cam they
use is a monster cam, it looks a lot like a Leinweber drag cam. Tall and 
very flat. This does not bode well for top end life. I wonder what a valve
job will cost on that set of heads. If you go with the kit I'd go with the 
Dellortos as the manifold is a bolt-on. Otherwide you'll have to make a 
custom plenum for your carb. I run a Dyna-S single fire on my stroker
and I can't say enough good things about it. It works extremely well and
it's cheap (at least compared to a single fire mag...$2500). IMO I would stay
away from this kit until they work the bugs out. I think a sidewinder kit is a
much better way to go, all around.

|>3.) Why can't harleys compete head to head with the Japanese bikes in
|>the drag circuit.  Engines sure seem large enough and there are
|>definitely nitro breathing Harely's.  I was at Indianapolis last
|>weekend at a drag bike event and didn't seem to be a single harley
|>(except those specators were riding, myself included).  Is the
|>weight/power ratio tilted in favor of the Japanese bikes?   Do you need
|>the higher RPM's Japanese bikes put out?  Is it something else?

They do. HD fuel bikes run the same kinds of speeds as the japanese bikes.
There are seperate racing organizations for HD and all others.

|>4). Are there there different types of nitro used for racing.  If so,
|>what are they.  Are they usually mixed with alcohol.  What is the
|>nitro really used for (a good source or oxygen some people have told
|>me, but I'm not convinced).  If this is the case, why not just strap
|>some O2 canisters to the bike (or maybe people are already doing
|>this).  Once you get to nitro bikes, are the engines usually injected
|>or carburated and what the advantages/disadvantages of both kinds.

Fuel bikes run pressurized fuel injection systems for lots of reasons,
like high fuel flow, and safety. You can run nitrous in the brackets if you
want, just don't break out. And plan on big bucks keeping the engine fresh.

|>5.) Are there some good sources of books one might find at the library
|>regarding high performance engines not requiring Mechanical
|>Engineering or Chemical Engineering degrees.  Seems like there
|>is an enormous amount of knowledge out their at least from the four
|>wheeled engine builders.  Does any of it get written down or is it
|>just stuck in engine designers and tuners heads?

Much of this kind of info are closely kept secrets. There are numerous
HD drag publications, usually associated with their organization. Go to a
HDRA or ECRA event and you'll find them.

CdH