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.;)