Hobbyking Aquastar 26CC engine bogs down at high revs.

Vince Fantauzzi · Jul 20, 2019

Does anybody have any idea why this engine seems to reach high revs for a time but then bogs down and shuts off? The engine starts and idles just fine.

Also, while on the water it will bog down before ever reaching high revs at all.

The engine is a Hobbyking Aquastar 26CC with rear exhaust and front carb.

Dennis Somers · Jul 20, 2019

Are you turning the choke "off" as soon as the engine fires?
Are you using a gas bag or a hard tank? If tank, is it vented properly?
What tuned pipe are you using and what is the "tuned length"?
The carb needles may need to be set properly. The carb pulse hole may be blocked.
The coil to flywheel gap may be wrong.

It could be any number of things including something wrong from the factory. You need to have someone with experience look it over for you.

bermudadude · Jul 21, 2019

most of those engines [the bad knock-offs] dont have walbro,or better,carbs. also the coils could be the problem. watched a guy mess with 1 for over a year lol it was hilarious and sad all at once [the carbs are no good right out the box]

Vince Fantauzzi · Jul 21, 2019

Thx for the replies guys... Ya, this engine never impressed me from the get go, but it was running ok for sport type fun.. One thing I also should mention is that the problems seemed to have started after it blew the carb insulator gasket, which I replaced... Could a piece of that gasket be jammed somewhere and causing the problem?

Dennis Somers · Jul 21, 2019

Those isolator gaskets have the pulse hole in them that must be lined up with the hole in the cyld. and the carb. Any gasket will not seal well if the old is not cleaned off completely, and the surfaces are not dead flat.

Any rear exh. cyld. that does not have a sleeve ( removable or cast in ) for the piston and ring to ride in, will wear out the piston and ring fairly quickly. That's because the piston is only thrusting against the thin transfer divider. Motors like this should be considered limited life, toy engines only. It's a toss up as to whether the toy interest will last longer than the motor.

Vince Fantauzzi · Jul 21, 2019

I hear ya... The only reason I went with this engine is because of the rear exhaust feature (space restriction in the hull)... I may end up switching to a picco 90 which is a bit too fast for sport boating, but I have one on hand..
Thank you for your input, I appreciate it.

Dennis Somers · Jul 21, 2019

The only semi-reasonable cost R/E gas engine that would last, is the RCMK 30 ( 29.5cc ). It has the cast-in sleeve, but might be hard to find. As far as the 90 being too fast, restrict the throttle on your radio.