Hi,

I have a problem tuning a Ryobi 31 single ring.

It has CH electronic ignition.

It starts fine, ad runs about 5800 rpm with 18 X 10 prop, but runs for about 30-45 seconds, then dies.

I remixed new fuel, charged ingition battery, and still the same thing. I know it is getting plenty of fuel.

Could it be getting hot from a timing too advanced perhaps? It ran fine on the bench with the ignition, but I have since had things apart and back together.

Also, on the stock carb, where should the needles be? I think the low end is out about 2 turns or so, and the high end has been in and out trying to get it right, to no avail.

any ideas? I'd love to test fly it sometime

thanks

Bill

bill
how long will it run on low speed?

Bill
do you have a choke ? if so try it half closed . will it run on low speed? whats it do when it dies?
if I remember correctly 2 turns outis safe starting point.

It seems to me that your prop may be a little too big. I did a Poulan 42 and ran an 18/8 around 8000. Timing can be 26 up to 32 BTDC with little effect. I have tried many settings and now use 28. Also what carb are you using? I would use at least an 11.5 mm on that engine. As for tuning, set the high first for max RPM then richen a tad. Set the low for transition then re check the high and go test fly. Adjust from there.

Thanks

It is the stock 2 needle carb. The high end needle seem sway out , to me.

The choke is a sliding metal plate. I thought it may have air leaks, so I removed the motor and

sealed everything.

WHen it runs, it runs strong for about 45 seconds, then dies, but not abruptly. Over about 10 seconds.

Sometimes I can throttle down, and keep it running. It will idle all day long. I am going to try another plug this evening.

Bill
I had a homelite do about the same thing .it had something in the hi speed needle
passage blocking it it would run for a short time on hi speed then act fuel starved
and quit,if I ran it on 1\2 choke it would run ,then quit as soon as you opened the choke.
Icant believe it would be a timing isue because it runs ok for a brief period of time,
try a smaller pitch prop,and see if it is still the same. clean the carb pull it apart blast
everything metal with carb cleaner blow out needles with compressed air ,reassemble
and try it again.(please take appropriate safety measures safety glasses,gloves etc.)
to check for an air leak ,spray gasket joints with carb cleaner as engine run ,listen for
change in rpm's, the rpm's should jump up breifleyif you have a leake, it doesnt sound
like one but if all else fails start at the begining .

Bill
what did you re-seal it with? ,new gaskets I hope.

A new gasket between the carb spacer and the plastic crankase cover.

I think I'll check the carb for dirt, etc.

18x10 sounds like a lot of prop for this, I always run 18x8's on my Ryobi, maybe the prop isn't the problem, but if you had an 18x8 laying around it would be an easy test.

G day,

Have had simmilar problems, firstly what is the engine cowl like ? we have been having a lot of trouble here in Australia this summer with in cowl heat which could explain why it runs on the bench ok. Make shure you have twice as much air out as what goes in. I have also had to install a heat shield between the carb and muffler on a couple of war birds I have to prevent vapor lock.
My starting point for both mixture screws is roughly one and one half turns out. Could also be that your high end is too lean, this will definatly cause it to die especially if there is a over heating problem in the coul as well.
Does it stumble as you go from idle to full noise? this also is just practice in tuning. I have been running 18 x 8 2 blade Master Airscrews but have reciently found 18 x 8 Bamboola props far more effecient and easier on the pocket.

Regards
Noel

hey, thanks, great info!

I haven't put the cowl on yet, but it will get plenty of air, as the cylinder sticks out the bottom.

I tore apart the carb, and it had *&*^% inside it..I thought I had cleaned it, but apparently I had not. It is definitely clean now...

Anyway, it ran good for a long time, but I believe I leaned it out too far and it got hot.

I am switching props and will run it tomorrow. I need to get a 18 X 8 somewhere, and maybe I'll try your bambula.

I'll let you know how it goes. Thanks for the starting points.

Try an APC 18x6W it works great on the Ryobi best so far I've tested.

aeronut how did you mount the apc 18x6w? My prop adapter is to small. Are you using a spinner? My old hub is from wacker engines.[8D]

Bill did you have a chance to test the APC 16x10W? I an curious because I am trying to determine which engine pulls harder - the 25cc homie or the 31cc Royobi.

In the racing world “There is no substitute for cubic inches.�

The Ryobi is almost 20% larger displacement.

Bill

Naw the correct saying is " The only substitute for cubic inches is cubic money"

An engine that runs for a while and quits is not getting hot, it's running out of fuel...Running out of fuel is caused by a clogged filter screen or a leak somewhere in the pulse passage, or a carb in need of a rebuild..
Usually if it gets hot enough to quit you will have some aluminum from the piston stuck on the cylinder wall..It stops REALLY fast when that happens
Pinch off the fuel line and see what happens, it just stops, no harm done...Can't run long enough to get hot and to seize...Pinching off the fuel line is one of the ways we use on Quicky 500s to kill the engine, a u bend in a piece of 1/16 rod pulls the fuel line against the firewall...On the big race plane we pinch off the pressure line to the carb, same thing, instant stop...

Well, I finally go t back to working on the ryobi - and I found the issue.

Air leak at the carb. I was missing a gasket on one side of the aluminum carb spacer.

Running a wood 18 X 8 I get about 58oo rpm. I am going to try a 17 inch prop next.

thanks for all the tips! Now if I can get the RPMs up, I'll be in there!


Bill