Ryobi tuning help
 

I have a Ryobi 31cc that was converted with a Bowman ring and ei igntion. I cant seem to get the high end to tune out. It sounds like it is running rich all the time, ie it has a 4 stroking sound. Cant seem to get that nice 2 stroke sound. Low end is fine. idles and transitions good. Has a tecumseh carb. Only one I have ever seen. I have tried changing the timing but all that seems to do is make it harder to start. The motor is inverted. The spark plug has a nice tan color like it is adjusted properly. The Bowman ring probably has 2 tanks of fuel run time. Should I try running it more to let the ring seat in more or is this carb just junk? Any suggestions?

Thanks
Jim

RE: Ryobi tuning help
 

You Have a carb issue. If you have a Walbro, try it. Go with a #28 venturi size. Is the carb the original one. Very small throat?? It will not rev with it. Also be sure your exhaust is open and not closed due to carbon.

RE: Ryobi tuning help
 

Could be too much carb as well.

With a carb thats too large, they will run up to about 1/3 or 1/2 throttle and then die suddenly when you advance throttle. As soon as the high speed starts to kick in and dump fuel it drowns the motor.

This is in extreme cases. But it's just something I learned along the way. Too much carb isn't any better than a stock carb. [8D]

RE: Ryobi tuning help
 

Sometimes a prop that is too small will not load the engine good to smooth out. What size prop do yo have on it? Just another thing to consider. Capt,n

RE: Ryobi tuning help
 

We are having the same problem.. Eng won't peak on rpm's. We have tried 16x8 and 18x6 props, but not much difference.. We only have about 2 hrs of running on it, so I'm hoping it will get better as it breaks in.. Converted eng w/ ei bought from JAG in Calif

RE: Ryobi tuning help
 

I have an APC 17x10 on it now. I believe the carb is somewhere around 10mm venturi size. Even if the carb was too big, shouldn't you be able to lean out the fuel enough with the high speed needle? I have some WT324 carbs off some give away chainsaws laying around. May try one of them.

Jim

RE: Ryobi tuning help
 

I think you are right...it should lean out with that carb....try another carb. Hope that works! Capt,n

RE: Ryobi tuning help
 

I had a Ryobi do this, and it turned out to be the reed valve not seating properly. (The reed valve seating area actually had a crack running through it in the plastic.) It sounded like it was rich and four stroking, but you could not "lean in it" and get a clean two stroke sound. Fixed the reed valve and now it runs normally.

AV8TOR

RE: Ryobi tuning help
 

No.

RE: Ryobi tuning help
 

It depends on how much to big it is.

But the basic answer is no, not really.

I'm working on a 65cc Stihl 4 stroke and for some reason the stock Carb has all the symptoms of being to big.

I have been thinking of putting a bushing in it to decrease the size of the ventury.

What do you guys think about that idea?

RE: Ryobi tuning help
 

Still having problems. Over the weekend, I removed the motor and put a known good back plate with reed valve on it. Swapped out the carb to a Walbro WT-324. Swapped the throttle lever and arm out of the Borg Warner carb and put it in the walbro carb. BTW it is upside down copared to the walbro. Tried to run it. Could not seem to get enough fuel in it. With the standard starting settings, needles opened 2 full turns, I could only get it to fire fully choked. It is pumping fuel as I can flip the prop and suck fuel up from the tank to the engine. If It just crack the choke open a little, I can get it to run wot but it will not idle. I ended up opening the needles to 4 full turns and could get it to run with the choke fully open at wot. But still no idle. Thought I might have another carb issue so swapped the carb out again with another WT-324 that I know was good off another engine I have. Same results. I cant figure out what the problem could be. There are no air leaks in the fuel lines. Swapped those out. I took the back plate back off and sealed it with RTV. Only idea I have left is that the throttle lever might be messing with the fuel flow. With it swapped around, the butterfly is opening in the opposite direction. But to fix this, I would have to re-engineer the throttle set up on the airplane. Only want to do that as a last resort. Also tried different spark plug. Made sure the head was on tight. What do yall think? My arm is sore from cranking on this thing.

Jim

RE: Ryobi tuning help
 

Be darn sure the Pulse Hole on the carb lines up and no leaks around it. Since you flipped the carb. Had the same issue happen to me but on a Fuji Engine.
If all is correct-Sounds like you have to adjust needles-High end first, then low. It may need to be open bore than normal or just the opposite. Very tricky when larger carbs are used. Is the Venturi size #28 ??

RE: Ryobi tuning help
 

Pulse hole is lined up correctly. I did not flip the carb. Just the throttle lever in the carb. I believe the carb opening on the 324 is 11.11mm. I adjusted the low end needle until it was almost falling out but still no idle.

Sore arm
Jim

RE: Ryobi tuning help
 

The throttle butterfly opening backwards is not allowing the air to flow as it should over the idle orifices in the carb.

AV8TOR

RE: Ryobi tuning help
 

That is what I was afraid of. I saw the 2 little holes in the bottom half of the throat of the carb and figured that was probably the problem. With the butterfly flipped the air path is disrupted going over the top of these holes.

However, That should not have affected the running at wot when the butterfly is completely open should it?


Jim

RE: Ryobi tuning help
 

With the butterfly backwards, the top end should still be ok, though it won't idle at all off choke.

RE: Ryobi tuning help
 

Now that I reflect back on it. I believe this is my fault as when I installed the first Walbro carb, I remember having to reverse the throttle servo. I put the butterfly on backwards!!!! Now I will have to take the engine off again [:@] and flip the butterfly over. But at least I wont have to re-engineer the throttle servo placement. Live and learn. Probably wont happen tonight. NFL action.

Jim

RE: Ryobi tuning help
 

Make sure that when you put the butterfly back in, the beveled edges are turned the right way too. I didn't realize they had that bevel on them until I put one in backwards... ;)

RE: Ryobi tuning help
 

Thanks,

I had not realized they had a beveled edge either. I will look for it. You may have saved me another bone head move.

Jim

RE: Ryobi tuning help
 

Took the Ryobi back out last night and compared the butterfly to another carb I had and sure enough it was in backwards. Funny how when I flipped it back over it seemed to fit much better. Just had time to remount the motor. Darkness kept me from trying it out. Weather permitting, I will try it tonight. Forecast is for rain.

Jim

RE: Ryobi tuning help
 

Be sure and let us know how it runs, I'm curious now! :D

RE: Ryobi tuning help
 

Gave it a try last night. Motor did have throttle response now. It would idle. Did not get a chance to adjust it in as I forgot to charge my ignition battery during lunch and it went dead on me. [:@] But at least I know for sure that the butterfly being on backwards was the cause of my no idle concern.

Stay tuned for more after I get the batteries recharged.

Jim

RE: Ryobi tuning help
 

Got a short time in last night for adjusting. I did get it to idle well and had good throttle response. But the needles are still baffling me. I ended up with the low needle out about 3 and a half turns. The high needle did not seem to have any affect on how it was running. At wot I could adjust it any way without a noticable change. I even closed it all the way. Still ran at WOT. And when I say it was running at WOT I mean that it was giving me a good clean run with intermitent burbles.

Does anyone have any ideas as to why the H needle is not doing anything or to what I am doing wrong.?


Jim

RE: Ryobi tuning help
 

You need to start over with the needles about 1.5 turns out each. Since one needle affects the other, you can get yourself into a postion where you've got one way too far open and the other about closed, and it will try to run, but not quite right. If/when that happens, just start over with the baseline 1.5 to 2 turns out on both needles and start fine tuning again.

If that doesn't do it, I'm afraid you have something wrong internally with the carb.

AV8TOR

RE: Ryobi tuning help
 

I have WT324 on 2 Homelite 30's and a Ryobi 28. The Homies swing 17-8 7800+ rpm the Ryobi 16/8 7500+ with mag ign.. But I have opened up mufflers on all. Just cut out the 1/3" ID pipe and put 7/16"(you do have muffler on it don't you?) , or for testing you could just leave the hole. The stock carb for 31 Ryobi is WT434. You could try that or any of it's 8-9mm venturi cousins (stock trimmer carbs) to isolate intake probs, but I've never had good luck running oversize carbs with stock exhaust, and never had the same symptoms twice:eek:. Just unable to tune the thing. Yea -let us know how you make out.;)

RE: Ryobi tuning help
 

So, it is possible for the engine to run on just the low speed needle if it is open too far? I will go back and start over. But I think I will take the evening off tonight though. Thanks for all the help.

Jim

RE: Ryobi tuning help
 

Yes. And Batguy is right too. If you are running the stock muffler, you really need to gut it and also provide more outlet area.

AV8TOR

RE: Ryobi tuning help
 

The muffler I am running has been gutted and a 1/2" x 1" hole cut in it. So should have plenty of breathing room. Looks like if I want to do any more adjusting, I'll have to do it tonight before Ike hits. Looks like rain for the next 3 days. This has been the wettest summer on record for us.

Jim

RE: Ryobi tuning help
 

How about a new one http://www.homedepot.com/webapp/wcs/...54&marketID=67 Take a look Capt,n;)

RE: Ryobi tuning help
 

Dang captinjohn-it's raining Ryobi long blocks [X(]-too bad some aftermarket genius hasn't come up with a better reed valve for these. They're calling them 30cc. wunder if it's a different engine or still the 31?

RE: Ryobi tuning help
 

That 30cc Ryobi looks to be a Homelite engine...with a newer type of carburator. Looks real easy to work on and mount to a airplane!!! Capt,n;)

RE: Ryobi tuning help
 

I believe they are the same as the Homelite 30 just rebadged as a ryobi

RE: Ryobi tuning help
 

Sounds like a good unit for the $$ http://www.homedepot.com/webapp/wcs/...egoryID=530582 Capt,n;)

RE: Ryobi tuning help
 

Gave it another try last night. Set needles back to 2 turns open apiece. Choked engine, set throttle to WOT and flipped until the engine sputtered. Open choke and flip, engine starts and runs full blast for about a second or two. Just long enough to burn the fuel from being choked. Choke again. Same results. At about this time, it stopped firing at all. Discovered that my hall sensor had come loose. I had used epoxy to glue it to a hose clamp then mounted to crankcase. Epoxy broke loose. I had debated on drilling and tapping the crankcase but did not want to remove the crankshaft to do it. Decided to give the epoxy one more try. So set it up to cure overnight.

In the meantime, I noticed that my throttle plate had not been opening all the way. When I get to 1/2 on my transmitter, the servo had reached its end point and the throttle was only about 1/2 to 3/4 open. I did not get the servo arm back in the right place. Was in too big of a hurry. So when I was trying to adjust the H needle last time and was not getting any response it was because the throttle was not fully open. My fault again. [:@] Problem is on the Ryobi, the throttle arm and plate are hidden between the muffler and carb and is hard to see. To say the least, I spent some time last night making sure it was set correctly and that I got full travel on the throttle. Now if Ike will just hold off a little longer, I will try it again tonight. If not, rain until Monday.

Jim

RE: Ryobi tuning help
 

How is your ignition timing set up at???? Maybe is your timing!!!!

RE: Ryobi tuning help
 

Timing is set at 28 Degrees BTD. I have had it running at this timing before. Back when I started this thread, the problem I had was that I could not lean it out enough at WOT. All of this effort was to fix that. All started when I swapped carbs and back plates. Timing should still be ok.

Jim

RE: Ryobi tuning help
 

You said opened choke all the way after full choke 1st flip..?? Up here in the great frozen north we usually keep full choke until start then quick about 2/3, then 1/2 until it warms up a little, then open. 1/2 choke like 30 seconds to a minute depending on how cold [&:]it is. High speed usually starts a 1 1/2 out, low speed 1/2 to 1. How's the compression on this (sorry if you stated before and I missed it. This is getting to be long thread)even though the rings are new? Anyway stay safe down there in TX.

RE: Ryobi tuning help
 

Since what is left of Ike is blowing hard outside right now, I decided to pull the carb off and go through it. I bought a repair kit yesterday. First thing I checked is the pump. All good. Next I took the regulator cover off and discovered that a too thick gasket was used under the diagphram. Next I pulled the needle out and found that the red was showing on the needle. Needs replacing. Then I shot carb cleaner through the needle openings and found that I had good fuel flow from the idle and high speed ports. This carb has the membrane check valve and it seemed to be working ok. It would bet wet but not allow a bunch of cleaner through when cleaner was shot through the needle ports. So I put a new needle in. Changed out the gasket on the diagphram. And then put back on the carb back on the engine. It should be good to go now. I think part of my problem was the bad needle and the wrong gasket on the diagphram. I also read on a web article that the diagphram should go on the body first then the gasket then the cover. So that is the way I did it. Made double sure the throttle was set up properly on the servo. Ike looks like will be out of the area by tommorrow afternoon so hope to try again then. I have learned a lot about how these carbs work over the last week. If I had known sooner, I might have saved myself some trouble. Most of it was my own fault.

Jim

RE: Ryobi tuning help
 

I know I shouldn't say this but that was going to be my second guest, the metering needle being stuck or to open, because you mentioned that it would only run after choking then it would sotp, that means no fuel through the metering needle, and then when the metering lever that lifts the needle is to high you thend to overflood the carb and thus the high needle is hard to set. I hope that the changes that you did work out for your engine. Good luck

RE: Ryobi tuning help
 

Ike cleared out early this morning now we have a beautiful day here in East Texas. Too windy to fly but just right for engine testing. Gave it another shot. Same thing, can not get a reliable idle or full speed. After spending a full tank adjusting, I shut it down to think for a while.

While watching the pregame show, only thing I could think of is maybe ignition. I have another ignition module so I was thinking that I might try it. But then I thought, it just seems like the engine can not draw fuel properly. What could cause that. I know it is not the carb because I have gone through it completely. Then I thought, also before I started all this, I was having a problem with interference so bought a resistor plug. The plug I bought was a RDJ8Y. The original plug was a DJ7Y. Pulled the plug out and compared it to the DJ7Y. The 8 does not go into the cylinder as far. So I thought maybe the 8 was letting the compression down by not sticking as far into the cylinder. So I stuck the 7 back in.

Fueled it back up and headed out into the yard. Needless to say, It improved immediatly. I could adjust the low speed needle to get a reliable idle and good transition. However, the engine would peak just before hitting full throttle. Keeping in mind that I do not have a throttle stop for WOT with the lever swapped end to end, I adjusted the end point on transmitter until the engine peaked at the same time the stick reached full on my transmitter. Engine is running perfectly now but now the glitching problem is back. Will have to order me a RDJ7Y plug to get rid of the RFI glitching.

I tached the engine with my Tower tach. Dont know how accurate it is but the engine sounded like it was hitting peak rpms. Using an APC 17x10 prop, I tached 6700 rpms at wot. and idle was at 2400 rpm. I grabbed the tail of the airplane to see how hard the engine was pulling and it felt like it had lots of pull. I dont know if this prop loads the engine more than the benchmark prop of 18x6. I have read that 18x6 should do around 7k to 7400 rpms. How does this compare in load to the 17x10? Dont have enough ground clearance to use an 18" prop on this plane.

Anyway, it felt good to get the engine running properly after struggling with it for over a week. :D Eventhough I still cant fly it until I get that resistor plug.


Jim