My ryobi 31cc 15" 700r won't start

change your battery

take off the muffler and try it again if better then open the muffler and clean the screen most pry open

if you have no spark and the kill switch wires are not shorted out then the coil is bad

Low compression could be due to carboned-up ring that is sticking. You could remove the exhaust muffler and look inside the port and check the condition of said ring by adjusting piston position. You probably wouldn't notice the start assist working if the compression is low, because the start assist MAKES it feel that way under normal starting conditions. Poke into exhaust port after removing the muffler with a sharp tool and see if the ring is free. It is not supposed to move much, just wiggle a little. If it is stuck, you should be able to tell and disassembly and cleaning will be required.

Hi and wel;come to FixYa, I am Kelly.
The part you need is item 9 on most parts lists:

Your problem is caused by either drive shaft failure or.. clutch failure. Most of the time the drive shaft fails before the clutch.

The manual is here:
http://www.mymowerparts.com/pdf/Ryobi_String_Trimmers_Blowers_Tillers/700r.pdf

Shaft is PN 682064 or 753-04280

Sears parts direct has the shaft as item 10 this link:
http://www.searspartsdirect.com/partsdirect/part-model/Ryobi-Parts/Grass-trimmer-weed-wacker-Parts/Model-700R/0909/1503820/10060718/00002?blt=06&prst=0&shdMod=700R

Detailed view:
http://www.searspartsdirect.com/partsdirect/part-number/Ryobi-Parts/Grass-trimmer-weed-wacker-Parts/753-04280/0071/247/Model-700R/0909/1503820?keySuffixId=NA&productTypeId=x&searchModelNumber=700R&subCompDesc=Boom%20and%20trimmer&brandDesc=RYOBI&modelDesc=TRIMMER&pathTaken=partSearch&blt=11

Lower price here:
http://www.mowpart.com/p661995/Flex,-Shaft-(Rpls-682064)/product_info.html

Average price ($32.50)

Thanks for choosing FixYa,
Kelly

Try this link:
http://lawnandgarden.manualsonline.com/manuals/mfg/ryobi/700r_1.html

I have a ryobi doule line bought in 1997..Had same problem put new gas cap on and problem solved..could not get air in....

I got on here to find the solution for the same problem. This seems to be fairly common. I need to have it at 3/4 choke to run properly. Other posts say the exact same thing, about the 3/4 choke. It is apparenly something that breaks occationally.

I'm going to remove the carb and take it apart. My suspection is the diaphram in the bottom of the carb. There isn't much you can do with the carb, it is very simple and has few parts.

There is a chance that it is a blocked passageway also.

There are instructions for adjusting the mixture, but they are not clear enough. I will be posting a clarification reqest on one of those posts. Will also post again after I check the diaphram.

try checking the fuel lines

As with all 2 strokes if you have compression and a reasonable spark, you only need fresh fuel with correct oil ratio) and they must go !(as long as you haven't fiddled first and all gaskets are sealing) I start mine by(1) pumping the primer till it is firm,(2) full choke,(3) pull till it kicks ONCE,(4) half choke, pull till it runs,allow to warm up and(5) switch to run (you may need to apply a bit of throttle while pulling as in (4)(or give it a few more pumps if it dies) If all is ok, check that when properly warmed up there is a smooth transition from idle to full revs, if it hesitates it may need the LOW SPEED mixture leaning (clockwise) SLIGHTLY.If it dies the LOW SPEED mixture may need richening(anti-clockwise)(adjust 1/8 turn at a time) Make sure that motor is just peaking at full revs and is on the RICH side of peaking (HIGH SPEED mixture)(this will avoid seizing it Adjust both till it revs cleanly and is JUST rich at full, and idleing nicely and it should start without too much trouble.(If you have fiddled and are lost,-about 2 1/2 turns out from closed on both needles should get you started)