This was emailed to me by a Seca 650 Turbo owner.  It should be useful 
for all you Turbo owners out there.


In 1987 I bought a used (6000 miles on it) 1982 Seca Turbo. It's life
ended when a drunk driver pulled out in front of me unfortunatly in
august of '88. Now, pretty much fully recovered, I've just purchased an
'83 Seca Turbo with 11,000 miles on it. 
I read some of the specs that you posted from Cycle Magazine. They were
wrong in a sense, that the 1982 Seca Turbo's boost presure was around
7.7 psi, that's true. The 1983 model, however, came stock with
approximatly 11 psi of boost. This greatly increased acceleration time
of course. I don't have any more real numbers for you in that
department, but, I can tell you a few tricks for future web browsers
that visit your page that own an '82. The 1982 Seca Turbo was released
as competition to the Kawaski GPZ 750 Turbo (The only other turbo model
I know the name of for sure), as well as Honda releasing thier own turbo
version in competition. Now, the GPZ 750 Turbo was the fastest
production in '82. So, in response, Yamaha took thier '83 model and
beefed it up. As you know, the exaust is a 4 - 1 system, the second
(right side) being the wastegate for the turbo. They added a check valve
(don't ask me where specifically, somewhere under the left side fairing
by your shin) and closed the wastegate pipe to half the open diameter,
letting the turbo produce 11 psi. Now, '82 owners don't need to worry
about this factory modification, as I checked into it and Yamaha offers
(my local dealer offered it still in early '88 and had 3 of them in
stock) a kit that the dealer can install without voiding any warranty on
the bike (Like there still would be one now...). Anyway, the kit cost me
around $35 US for the kit and installation. I'm sure there's still a few
kits out there, but if not, I think the micro fisch would have some sort
of specifactions and could probably be fabricated fairly easily. Like I
mentioned above, I have no idea what the check valve connects to, or
what it looks like, but if you need to, I have both bikes, and I could
check the I.D. of the (I swear it was just a washer they welded to my
'82) "washer" and let you know at least that information. A dealer could
probably release some other info on the check valve.
That's the real trick/tip I have for you. I love the Seca Turbo, which
is why I bought another one, and I'd like to find other owners local to
ride with/talk to and others on the internet to email, as well as see
your page grow. See, I learned to ride at 14 on a 750 Seca (half
fairing, there were two fairing packages out, half fairing, and a
fairing like the Seca Turbo, with Luggage) and then I really practiced
alot before I got the Seca Turbo on a 550 Maxim, so I'm definitly
interested in your page. If you'd like any pictures of the maxim or Seca
Turbo (don't know if I've got any of the 750 Seca, but I can ask my
brother, it was his, and I'm sure he does), let me know, I've got a good
HP 3c scanner and can scan them and email them to you in any format
you'd like.

Now, for the next tip on the Seca Turbo. For better traction after the
Turbo add-on to 11 psi, I found the bike alot more controllable going
with a tire size one size wider, and I'm going to have to look up that
size if you want to know an exact spec there as well. Anyway, let me
know, and keep up the good work on the page! 

Bryan
Swampy@datadepot.com
Cerritos Area (Los Angeles), CA