Plunger Primer

[GeneWeber]

Hi Folks,

Has anyone used a Plunger Primer for their Rotax engine set up instead of an inline bulb primer? (CPS 2004 catalog, pg 258, PN 8613) The Plunger pumps gas into primer port on the newer Bing carburetors. Any experience using this?

Thanks & Regards,

Gene

[ToddP]

Yes, I've got one. It works great.

[chuter]

I use both; the bulb fills up the float bowls, and the plunger squirts in behind the throttle plate. Makes starting much easier.

[Chuck Irby]

Gene, I also use both. That's the only way to go (IMO).

[GyroRon]

Ditto all that above

[GeneWeber]

Thanks guys.

[Doug Riley]

They're actually apples and oranges. The plunger primer is an update and substitute for the "choke" or enrichener circuit on the older Bings. In that role, it's a huge improvement... especially in cold weather. The plunger can be used on the 912 carbs as well as the 2-stroke carbs, and doing so on the 912 eliminates the need for extra throttle cables and levers for the "starter carb" circuit.

The squeeze bulb doesn't put any gas into the engine, it just fills the float bowls. A squeeze bulb is handy to have, but install a shunt line around it so that it won't cut off the gas supply if its internal check valves stick. I've never had one jam up like this, but there are stories a-plenty.

[GeneWeber]

Hi Doug,

Thanks. Regarding the plunger primer as an update and substitute for the "choke", Ernie Boyette told me he doesn’t use the chokes on the Rotax engines. He said sets them open (not completely sure how) and fills the cable hole with silicone (I think :o ). I didn’t pay close attention because at the time defeating the choke seemed like an odd idea. Sounds like this works fine if the plunger primer is used.

Best Regards,

Gene

[gyropilot]

...install a shunt line around it so that it won't cut off the gas supply if its internal check valves stick. I've never had one jam up like this, but there are stories a-plenty.Doug,

I've heard this story also (who hasn't?), but I've yet to read an actual first hand account, or talk to anyone, who's ever experienced a squueze bulb failure. Over the years I've begun to wonder if the "squeeze-bulb-fear-story" is like so many other stories floating around out that take on a life of their own without the hard evidence to support it. Reminds me of the Rotax 2-stroke oil-injection unit failure fears.

Now of course the redundancy concept that has merit and adding a shunt is cheap insurance. But personally I think the risk of a squeeze bulb failure / malfunction is overblown... so long as a good quality marine-grade unit is installed correctly and it's replaced periodically (before the rubber deteriorates). I've seen some really crappy cheap imported squeeze bulbs being sold by some ultralight aircraft part dealers that I certainly wouldn't put on any aircraft of mine... maybe a lawn mower in a pinch.

But if it makes a person feel safer, then by all means put a shunt around the squeeze bulb and toss out the oil-injection unit. Everyone needs a security blanket to cuddle in. :)

Fly safe,

John L.

PS: The primer pump is *wonderful* thing. Wouldn't have a 2-stroke without it.

[Doug Riley]

Gene: Yes, if you can fit the primer, the choke is unnecessary. The older Bing carbs don't have a fitting on the carb for the primer input, however.

Why, John Landry, how dare you say such mean things about those trashy squeeze bulbs sold by Airstar Discount Sales?

Seriously, they are (or were) pretty bad.

[Aussie_Paul]

I have always run an electric facet type pump as redundancy and to prime the carb bowls.

I then used to "blow in the tubes" to prime the engine. Ah that lovely fuel oil taste that real pilots love!!!!!!!! I am sure a lot of you did this to save pulling the engine over quite a few time to get the "fuel enrichment" not chokes to work. A big saving on starter ropes when you did 300 hours per year.

When the primer became availible it was great. Being able to conduct everything from the seat for start up was great, but I did miss that "taste"!!!!!!

Aussie Paul.

[Mad_Man_Mike]

Believe me Squeeze Bulp primers DO fail --Ive had two such occurrences when I used to fly two strokes (MACs) on one occasion the one way valve became jammed and reduced the fuel flow--and the second time the bulb cracked and the fuel flow stopped -- both of these bulbs were less than a year old at the time.