914 Loss of Takeoff Power

If you’re pulling the carbs apart you might want to check the float weights.

There is an enrichment solenoid on the 914 air box, with three rubber hoses leading to it.  At boost (I think 108% throttle) it supplies air box pressure to the top of the carbs, which would otherwise be incorrect.  I have had one of these stick before and affect the operation on the carbs and running of the engine.  

It is worth checking if this is still operating and can be easily done by having someone (if you can’t teach yourself) place their finger on the solenoid and then switching the power to it on and off (most likely through the master switch).  It will click, which you can feel.  In a quiet hanger you may also hear it.   No click - and the solenoid is not operating and you will not get full boost.

replacement in the U.K. is approx £150GBP.

Thanks for the advice, Tim. I’ve pretty much narrowed it to a carb issue, probably because they haven’t been serviced in ~300 hours. We’d discovered the airbox actually rattled loose during some rough starts, and wasn’t able to supply that boosted pressure back to the carbs in the takeoff roll.  Think there’s some junk gumming up the carbs, and also the rubber seals are cracking and need replaced. Biggest lesson learned was to have a more thorough pre-buy and thinks to look for on the next engine!

I’ll look at that enrichment solenoid, Harry. I’d seen it before but wasn’t sure what it was. Should be an easy enough check to trouble shoot. Thanks!

Here’s some closure-I got my engine going again yesterday after several months of down time. I had several issues, and I’ll outline them in probable chronological order with solutions. 

1. Rubber connecting the airbox to the 2/4 carb was dry rotted. (Replaced all rubber connected to the air box).

2. 2/4 carb was contaminated, plunger was gummed up and not allowing the carb to function-this meant only half the engine was working, and caused a wicked vibration (rebuilt both carbs). 

3. Severe vibration from only half the engine working rattled loose the airbox on the 2/4 carb (replaced rubber, reinstalled carb, safety wired airbox to both carbs).

4. Vibration also broke the P-lead on the B lane ignition module (replaced connector beffort the break).