Dual Carb EA-81 hesitation...

[Kevin_Fogleman]

when advancing throttle into secondaries. After a second or so it revs up to full and does great. Any help or advice? Some think the secondary jets need to be changed. Some think distributor might need adjusting (adjusted for maximum rpm on static rope). Other info: Direct Drive, max rpm's 3450.
Thanks everyone for a great forum!

[MMorgan]

My EA-81 does the same thing....I have a single carb.

It only has this slight hesitation around 3200-3300 as the throttle is opening up.

When I first got the machine the timing was up around 25-30 degrees and there was no hesitation. Timing is now around 10 degrees at 700 rpm with the vacuum advance plugged and the hestiation is there.

[GyroRon]

This is the gyro Kevin is talking about. It is his now. Kevin, don't forget that your gyro sat in John Mini's - the guy I bought it from - Garage for a few years un touched and the gas had turned to gel in the fuel system. Have you completely taken apart the carbs and cleaned them? Might have some goo in one of the passage ways.

[Kevin_Fogleman]

No, I haven't, Ron, but probably should, eh? Otherwise, it runs perfectly.

[GyroRon]

the gas in that thing stuck to high heavens! I would suggest cleaning the carbs. Hope you bring it to ROC.

[Kevin_Fogleman]

Yes, coming to ROC! Update on hesitation... it is at all throttle settings, when accellerating, not just the secondaries. From my experiences back in high school with carbs, (never successful) how hard or easy is it to clean them? Wer're not talking about rebuild kits, are we?

[GyroRon]

Probably so Kevin. Look I am hoping for good weather and plan to fly down to the Briar Patch Tomorrow Morning to see you guys and hang out. Maybe if your there we can tinker with it some and see what we can find out.

[PW_Plack]

Kevin,

If you get hesitation when advancing the throttle from any setting, you may have a bad accelerator pump in the carb. I've never worked on a Soob, but it probably has a Holley on it anyway.

DO THIS OUTDOORS!

Run the engine up to operating temp, then lower the throttle to idle, and shut it down. Pull the air cleaner. If you have a choke, block it open with a clothespin, or some other object which won't block movement of the throttle butterfly below. When you quickly advance the throttle with the engine off, you should hear a hiss and smell fuel as the accelerator pump shoots a small amount of gas into the manifold as a fine mist. If it's weak or not happening at all, you'll be running extremely lean for a moment right after a throttle advance, causing the dip.

Some Holley carbs use a diaphragm-type accelerator pump, and they can dry out and/or break and cause the accelerator pump to quit. No matter what type of pump you have, a rebuild kit will always include the replacement parts you need.

[Kevin_Fogleman]

PW, thanks for your reply. I had already done what you suggested and they both seem to be working properly. Also checked vacume advance on the distributor and it checks out too. I don't have any info on the dual carb ea81, but the service manual for a single carb American model says the carbs are either hitachi or carter/weber.

[GyroRon]

Kevin, sorry I didn't make it down today. Weather was supposed to be questionable and I decided not to stray that far from home. Maybe next weekend.

[Aussie_Paul]

Kevin I am testing an ea-81 single carb with vacuum opening secondary. When you go for some quick power there is a slight delay and then the secondary opens and you get a good increase in power. This is the first time that I have experienced vacuum opening secondaries.

The engine has a 2.1 to 1 ratio ribbed belt redrive, and a 70" Warp prop.

Aussie Paul.