Saito .72 help needed

[John Pavlick]

I don't think it's a lean mid range. It sounds like it's got too much pump
pressure.

How is your tank set up? Is it the standard two-line vent / overflow at the
top, klunk pickup? I recently had a lot of fun with inverted motors where
the tank is mounted higher than the carb. You may be having some of the same
problems I did (fuel siphoning) so here's what I did to solve it:

1. Set up the tank for Uniflow with 3 lines: one for pickup (klunk #1), one
for the vent (klunk #2) and one for overflow when you fill the tank.
Normally this line gets plugged. Here's a link to describe how this works -
http://www.fraserker.com/heli/uniflow/how_uniflow_works.htm

2. Use a Fourmost (or equivalent) check valve in the vent line (not the
overflow line). This should let air in and no fuel out. You need this with a
Uniflow setup to stop the fuel from siphoning out the vent.

3. Plug the overflow line (use a fuel dot) after filling the tank.

4. Use the Perry Pump.

 That's it. It should work better than anything you've ever seen. I'm
running this setup on a 2-stroke and I needed to lean out the pump to get a
good mid-range and transition. On the VP 30 pump (not the one you have) you
turn the set screw anti-clockwise (out) to lean the pump. I believe that
yours is the same but you might have a nut instead of the set screw.
 Start with the high speed needle first. I usually run my 4-strokes on the
rich side. It should definitely be running at least 500RPM less than MAX
(lean - best). Here's a tip: If the high speed needle needs to be open way
more than when you run the motor in a non-pumped setup, then you need to
increase the pump pressure. If on the other hand, the needle is almost
closed and it's still running rich, then you need to decrease the pump
pressure.
 Set the idle needle and then check the mid range. If it's very rich, you'll
need to lean out the pump and repeat this whole process.

I hope this helps. If anyone thinks of something I missed - let us know. The
Uniflow arrangement isn't entirely necessary when you're using a pump, but
it works to help reduce the siphoning effect of a tank mounted higher than
the carb. The oscillating pump is sensitive to orientation so maybe someone
has found a better way to mount one...

John Pavlick
http://www.idseng.com





> -----Original Message-----
> From: discussion-request at nsrca.org
> [mailto:discussion-request at nsrca.org]On Behalf Of Wladimir Kummer de
> Paula
> Sent: Sunday, November 07, 2004 6:00 AM
> To: discussion at nsrca.org
> Subject: Saito .72 help needed
>
>
> Hi folks,
>
> I´m running a Saito .72 in a Aresti .40. The engine (mounted inverted,
> OS F plug) is equiped with a Perry oscilating mounted as per
> instructions, the tank is on the balance point (about 8in. from the
> spray bar). I´m getting a erratic run. Seems to be over rich at the ends
> (top and idle) and takes about 3-4 seconds to pick up rpm as the barrel
> is opened, maybe a lean mid-range. What could be wrong?
>
> Cheers,
>
> Wladimir Kummer de Paula, MD
> Neurology Clinics
> Sarah Network of Rehabilitation Hospitals
>
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