[Spridgets] Harley Twin Cam

Kirk Hargreaves khargreaves2 at gmail.com
Thu Mar 19 10:44:42 MST 2009


I heard mention of the Harley Twin Cam. . .

I had one and rode it for several miles a year for 7 years.

Crank case began to make a slight noise.  Had the engine rebult at 12k miles
(under extended warranty).

At the same time I added the Harley big bore kit, 1550 cc's and 203 cams,
plus a few other goodies.

However - I read an interesting column by Donnie Peterson who is the tech
writer for American Iron magazine.

When the Twin Cams were coming out Donnie reports hearing a conversation
amongst Harley execs regarding the reason for the company's decision to go
to a Twin Cam design.

Supposedly, according to this conversation, the motor company was asked by
the EPA to run quieter engines.

(As though chain driven cams would make a difference since most of us add
louder pipes to our bikes anyway).

The EPA said nothing about Sportsters which run 4 gear driven cams.  I guess
since the sale of Sportsters might be much less than the sales for Harley's
bigger bikes.

But this is the EPA, so go figure.  Harley said that they could drive their
cam with a chain system which would
quiet down the engine.

Upon looking at the situation the motor company realized that to run a chain
drive cam - the heads would have to be taller and as such the bike would
lose it's look.  The motor would look more like the tall cylinders on a
Polaris Victory bike.

So they decided that the only way to do such a set up was to run twin cams.
This way the engine continues to have the same basic dimensions as the older
EVO unit.

So, according to Donnie Peterson, the Twin Cam came by way of the EPA.

Since S&S continues to refine the EVO design - and less moving parts might
make sense. .  seems to me that the use of two cams might be superfluous.

Kirk
59 Bugeye
And one time an owner of a very nice 1550cc lowered Road King with a LOT of
money invested in the thing.
After a second back surgery, this last one lasting 5.5 hours, my surgeon
advises me not to risk a fall on a two wheel vehicle.  He also advises me to
only drive cars with automatic transmissions!  So I guess he would not be
too happy to see me out every day in my Bug Eye. . .


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