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Requesting Advice on replacing flange/boot between carb and intake manifold?

  • Skyranger2
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2 weeks 1 day ago #20720 by Skyranger2
During inspection found a crack in the rubber boot/flange
(15-00392 ROTAX 267-789 RUBBER FLANGE ASSY)
that connects the carb to the intake manifold on right side carb.
Ordered two (figured replace right and left while at it) from CPS and have them here.
See photo attached.

Several questions.... one specific:
# Where can I find the torque for the two nuts that will hold the flange on the intake manifold?
(Preferably without having to wade through the whole heavy maintenance manual.)
Or better yet, one of you who has quick access to it, could you just tell me the torque spec?

# Is there any seating compound or gasket sealer or grease recommended or advisable to go between the flange and the intake manifold?

# Any general tips or things to watch out for on what LOOKS like a simple straight-forward remove and replace two nuts job*? Any gotch'yas? Am I going to mess up the mechanical sync badly or at all when I have to back the carb off the old rubber boot in the process of removing and replacing the flange?

All help appreciated.

Al
* (More than once I've started what looked like a completely simple R&R job and shot myself in the foot <g> due to what I didn't know.
My father used to say "A fool never learns, a clever man learns from experience, a wise man learns from others' experiences. I strive to be a bit closer to wise by leaning on you folks who have learned from experience <g>.)

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1 week 6 days ago #20728 by Kevin Stewart
See the following section from the heavy maintenance manual:

3.5.2) Carburetors and carburetor sockets
See Figs. 73-39/1, 73-40 and 76-41.
Attach carburetor socket (4) and new O-ring (5) with hex. screws (6)
M8x25 and M8x30 (7) with washers.
◆ NOTE: On intake manifolds without an O-ring groove, a gasket
(8) (see Illustrated Parts Catalog) must be fitted.
The screws are locked with LOCTITE 221. Tightening torque 15 Nm
(133 in.lb).
Fit carburetor into carburetor socket, which should be free of grease
and oil, align and fix with hose clamp (9). Tightening torque 2.5 Nm
(22 in.lb).
Check distance of 5 to 6 mm (0.2 in. to 0.24 in.) on allen screw (10) as
this is important to allow free movement of the tension spring (11).
Engage tension spring in the bracket (12) using a suitable tool.
■ CAUTION: To ensure efficient carburetor suspension, a distance
of 40 mm (1.57 in.) between allen screw and engagement
latch must be respected.
The following user(s) said Thank You: Skyranger2, kiwiatd, erikdahlbeck

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1 week 2 days ago - 1 week 2 days ago #20755 by Skyranger2
Much Thanks Kevin.

As I suspected there's some nuance to it... and you saved me some wandering around in in the heavy maintenance manual.

As for "NOTE: On intake manifolds without an O-ring groove, a gasket (8) (see Illustrated Parts Catalog) must be fitted."
Wouldn't you know it that there's some "maybe" aspect of it I won't know until after I pull the flange off the intake manifold... and that it would be a PITA to even identify, let alone obtain, that "_maybe_ needed" gasket beforehand. ;-)

Oh, and one small gotch'ya appeared: The ROTAX 899-471 ILLUSTRATED PARTS MANUAL 912 / 914 it refers to find the possibly needed gasket is shown at
www.cps-parts.com/catalog/rtxpages/15-02606.php as Part # 15-02606 at a price of $192.

Yeah.... turns out that's only for a paper catalog.... and you can download the parts catalog free.
But not easy to find that gasket as a search for "gasket" turns up hundreds of hits, as does "intake manifold" while "intake manifold gasket" finds nothing. <sigh>
Last edit: 1 week 2 days ago by Skyranger2. Reason: A tad more complaining ;-)

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1 week 2 days ago - 1 week 2 days ago #20758 by Bill Hertzel
Here You Go!

912/914 Illustrated Parts Manual.
All 202 pages Free of charge! :)

www.rotax-owner.com/pdf/IPC_912_914%20Series_ED4_R3.pdf

See section 73-10-00 with notes describing which parts you need based on your engine serial number.

What engine model are you repairing?
Serial Number?
Last edit: 1 week 2 days ago by Bill Hertzel.

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