Subject: [TR] TR3 carb bushings

From: Frank Fisher <[email-masked]>
Date: Sun, 11 Nov 2012 10:54:43 -0800 (PST)

i try to support T-R-F every opportunity, but their web site and printed literature just confound me.
some time back i seem to recall they had a carburetor kit that used bushings instead of oversize throttle shafts.
as i have a brand new set of throttle shafts that would be a less expensive route.
i can call TRF tomorrow for the part number.
but it seems to me, i would have to ream out a lot more meat than the oversize shafts. no?
has any one used these and if so how did you like?
thanks
Frank

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From: "Randall" <[email-masked]>
Date: Sun, 11 Nov 2012 16:25:35 -0800

> some time back i seem to recall they had a carburetor kit that used
> bushings instead of oversize throttle shafts.

RFK138 is the kit with two bushings and one shaft.  I don't know of a full
rebuild kit that includes the bushings.

But the price has gone up until it makes more sense perhaps to just send
them the carbs and let them install the bushings.  A pair of kits is on sale
for $112, while the rebushing service (RBCB101, which includes the kits) is
only $139.

> as i have a brand new set of throttle shafts that would be a less

The bushings are a standard hardware item I believe.  I'm not sure what
material is in the TRF kit, but it looked like solid bronze rather than
Oilite (about $5 ea @ MMC).  Or it might be entertaining to try something a
little higher tech, like maybe graphite impregnated sintered bronze (under
$1) or Rulon J ($10 but still a lot cheaper than TRF).

> but it seems to me, i would have to ream out a lot more meat than the

Quite true.  In my case the wear was more than the oversize shaft would
cover, plus the oversize reamer was way expensive, so I went with the
standard shaft & bushing route.

> has any one used these and if so how did you like?

The bushing installation turned out a lot easier than I had expected.
Lacking the tools to do it right, I cobbled up a center by clamping a piece
of scrap wood in the drill press and using an extra-long 1/4" bit to drill a
hole that I could mount a 5 flute countersink into, as a center.  Then
without moving the press table, I held the carb by hand with one side
against the 'center' while I carefully drilled into the other side.  Used a
drop of Loctite to secure the bushing in the slightly oversize (but not
much) hole.  On the first carb, I had to borrow a 5/16" valve stem reamer;
but the second carb came out perfect without reaming.

I've lost track of when that was, maybe around 1990 or so.  Anyway, those
carbs are still in use (I moved them from the wrecked 3A to the 'new' TR3).

Next time, though, I will use the "backwards reamer" approach.

What they don't tell you is that the new shafts are not drilled for the pins
that locate the throttle stops. Getting those located at just the right
angle, and just the right distance from the throttle plate slot, turned out
to be the hardest part for me.  I just recently realized that the front carb
stop was slightly too far back, and so was not locating the shaft properly
fore/aft, leading to erratic idle rpm (that always seemed to creep up when
the engine was hot).  I added a .010" shim which helped a lot, but I think I
need to go back and recenter the throttle plate again as it still hangs up
just a bit.

Randall

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From: "Randall" <[email-masked]>
Date: Sun, 11 Nov 2012 16:42:18 -0800

> What they don't tell you is that the new shafts are not drilled for the
> pins that locate the throttle stops.

I forgot to mention: Drill for the pins _before_ you cut the shaft to
length.  That way, if you goof, you can turn the shaft end-to-end and try
again.  The extra hole will be hidden under the spring, and won't hurt
anything.  Don't forget to deburr the hole (both sides) before doing a trial
fitting.

Randall

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From: Doug Hamilton <[email-masked]>
Date: Mon, 12 Nov 2012 18:12:07 -0700 (MST)

I haven't been following this thread from the beginning  so I don't know if this has been mentioned but Z Therapy used to do roller throttle shafts with rubber seals for most models of SU carbs. I haven't used them myself but have seen their work and it looks good.
http://www.ztherapy.com/

Doug

Date: Sun, 11 Nov 2012 16:42:18 -0800
From: "Randall" <[email-masked]>
To: "'Triumphs'" <[email-masked]>
Subject: Re: [TR] TR3 carb bushings

Randall