2 cycle starting problem

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  #1  
Old 05-06-03, 06:33 PM
jhorner
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2 cycle starting problem

Hey guys!

Great stuff in these forums. I'll surely be checking back often for advice.

I have a ryobi 700r 31cc string trimmer that is really hard to start, meaning I'm sore by the time I've pulled the cord 3 times! I have replaced the pull cord sprocket 4 times now because the teeth continue to break off. My first inclination was to comission someone to make a sprocket made of iron or aluminum instead of nylon, but that might get too pricey

After reading a thread on high compression from April (I forget the poster's name), I believe my trimmer may have a similar problem. If I remove the spark plug, the engine turns over with the greatest of ease. But when I put the spark plug back, I have to pull so hard that it strips the sprocket.

But when it starts, it stays on and runs great!

In the other thread I mentioned above, there was really no advice given. The poster just took apart the engine (which I'm a little reluctant to do) and cleaned everything, replaced fuel lines, added new fuel and oil, and that's it. He claims that it starts on the first pull now.

So what's my problem? I've been really proud of myself for figuring out how to open the trimmer up and change the sprocket. I've even messed with that stinking coiled wire that makes the pull cord retract (which I gently handle now). It's sprung out before and is a royal pain to get back in. I've spent so much time on this piece of crap that I'm about to give in and buy another brand. But I'd really like to know what the problem is.

Thanks in advance for any advice. Again, I'm really impressed with this forum. Do you guys get paid?

jhorner
 
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  #2  
Old 05-06-03, 07:44 PM
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Nobody gets paid, it's just people helping just to help. Where else do you find that? As for the ryobi, as mentioned before, they are considered "consumer grade" equipment. I am by no means bashing ryobi. My favorite string trimmer is a ryobi, they're light and inexpensive. However they are also made to last for the expected useful life and the parts are of lesser grade. Also, if you ever decide to buy another ryobi, you have a spare for parts. Small engines do have high compressing, especially 2 stroke engines. Chainsaws have the same problem, however, they use compression release valves.
 
  #3  
Old 05-06-03, 10:36 PM
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Hello jhorner!

Welcome to the small engines forum! Thank you for the compliments! We don't get paid, in the traditional sense of the word. We do enjoy helping people, and that, along with the challenge is why we do this.

Beofre you attempt to start your trimmer, remove the plug and look at it. Is it wet with fuel? Does the engine seem to be flooded with gas? This is apparently a common problem with Ryobi trimmers, which are poorly made. Normally when a 2-stroke engine floods, it is because of a carburetor problem. Ryobi seems to have a problem with this though, and some members have reported installing brand new carburetors to no avail...the thing still floods. Are you storing the trimmer vertically? If so, try storing it horizontally.
 
  #4  
Old 05-07-03, 05:42 AM
buttlint
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j,

I have run accross the problem you are describing a few times. ( I would like to see the post you are refering too also)

I think what you are saying is that, the pull cord gets ripped from your hand when you yank it over. That it pulls so hard, and jerks so violently, that it breaks the teeth of the starter pulley.

The problem was a seized ring. I suppose that a sheard flywheel key might do the same thing. I know the problem well, but I dont get to repair it often, because of the cost involved. ( cost >value) I am curious what others with more ryobi experience, have found to be the problem. I called ryobi once, but they act like they have never heard of the situation (bs)

I dread when I see one of those come in for a "starter repair" or a broken rope, because I can never be absolutely sure what caused it, until I fix the starter and find that it rips my arm off. Then its to late to back out of the job. (started fixed-cause not fixed) You have been thru it 4 times already, so you know what I mean.

I dont want to be the one that tells you to pull the cylinder and check in that area(although its not really that big of deal if you have the time) but its the only time that I can say, that I fixed the kickback problem. You may just want to remove the muffler and check that the ring is free in its groove. ( push on it with a pick or something pointy) Also check for a lot of blow-by, ie, dark deposits on the sides of the piston. Its not a fool proof method ( the ring may be seized or broken on the side you cant see) but at least its a start.

Sorry if I raised more questions than I answered, but I am in the same boat as you are. There are a ton of guys around here that have a great deal of ryobi experience, and I am sure they will clue us both in, on whats going on. 'lint.
 
  #5  
Old 05-07-03, 09:01 AM
jhorner
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Originally posted by buttlint j,

I have run accross the problem you are describing a few times. ( I would like to see the post you are refering too also)
You can find the "high compression" thread on page 2 of "Small Engines". It was authored by user kmtischer on 4-23-2003.

I think what you are saying is that, the pull cord gets ripped from your hand when you yank it over. That it pulls so hard, and jerks so violently, that it breaks the teeth of the starter pulley.
Yes!!! Exactly!!!

The problem was a seized ring. I suppose that a sheard flywheel key might do the same thing. I know the problem well, but I dont get to repair it often, because of the cost involved. ( cost >value) I am curious what others with more ryobi experience, have found to be the problem. I called ryobi once, but they act like they have never heard of the situation (bs)

I dread when I see one of those come in for a "starter repair" or a broken rope, because I can never be absolutely sure what caused it, until I fix the starter and find that it rips my arm off. Then its to late to back out of the job. (started fixed-cause not fixed) You have been thru it 4 times already, so you know what I mean.

I dont want to be the one that tells you to pull the cylinder and check in that area(although its not really that big of deal if you have the time) but its the only time that I can say, that I fixed the kickback problem. You may just want to remove the muffler and check that the ring is free in its groove. ( push on it with a pick or something pointy)
Hmm... now I've taken off the muffler and seen the piston head (I may not be using the correct vocabulary) move in the cylinder, but what's the ring you are refering to?

Also check for a lot of blow-by, ie, dark deposits on the sides of the piston. Its not a fool proof method ( the ring may be seized or broken on the side you cant see) but at least its a start.
Yes! so that's what it's called. I have seen some blowby on the side of the piston. It looks like burnt oil deposits.

Sorry if I raised more questions than I answered, but I am in the same boat as you are. There are a ton of guys around here that have a great deal of ryobi experience, and I am sure they will clue us both in, on whats going on. 'lint.
This is great!! Now I have a reason to open up the darn thing and try to fix it. I've never opened up the engine, but I'm willing to try and do it myself. Anyone have any pointers to diagrams of common 2 cycle engines?

Thanks again!!!

jhorner
 
  #6  
Old 05-08-03, 12:12 AM
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hmmm...I was thinking of fuel lock in the engine. (since the recent rash of flooding ryobi posts, lol). How would a stuck ring cause too much compression? Seems like it would cause a loss of compression. (Not at all doubting you 'lint, just wondering).
 
  #7  
Old 05-08-03, 05:52 AM
buttlint
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Cheese,

It's quite alright to doubt me on this one, bud If I knew what I was talking about, I wouldnt ask the question.

It is just that I have run accross this problem numerous times, and the only time that I have ever cured it, a siezed ring was the only cause that I could verify. (it very well could have been another problem along the way that was unwittingly fixed) Perhaps, in the process of cleaning the piston, to free up the ring, I removed the carbon build up which may have been the real culprit. I dont know.

I am as much in the dark about this one, as J is. I just know that it hurts like hell, when one of these little buggers bites back! And I know that it is problem unique to ryobi products(including ryobi dressed up like toros) I certainly dont have the experience that others on this board have, with ryobi products. (although I see more and more of it every year) Homelite and Sthil and Mac, are the products that have dominated the market, in my area. Those are the products that I understand and can speak about with some expertise. Not Ryobi.

As far as the rash of flooding posts go, walbro and zama carbs are common to most trimmers for the last 100 years. I have seen thousands hanging over my bench and tool box, so I am accutely aware of drips of fuel all over my stuff, including my lit cigs! To be honest, its rare that trash between the needle and seat is a problem. (The filter and the screen are really pretty effective.) I have many more problems in that area with stihl products leaking fuel from vent problems. So in my mind, fuel flooding the combustion chamber, isnt that big of a problem, proportional to the amount of press it gets.

The trimmer season hasnt really kicked in yet here, and when it does, and I start seeing more ryobi stuff, I will get up speed. I dont want to start making up stuff just to fill out my post count. I agree that it doesnt make any sense, that is, a low compression situation, shouldnt cause high compression symptoms. That is why jhorner and me are in this post together. We both know the problem, but neither one of us really know cause.

When I personally have run accross the "hard pull, kick-back" thing, I have always gone for the "fuel in the cylinder" theroy. Thing is, that has never proven to be a problem.(15-20 times?) One would think that the odds would kick in at sometime. You would think, that at least one time in twenty, I would have found a flooded cylinder, cured it, and moved on to the next job. It just hasnt happened.

I am more of a " I have done 6 million of them" mechanic. And I know that there are guys around here that have done their 6 million ryobi trimmers. I am just waiting too see what they say. I dont mean to lead J on a wild goose chase( although we seem to have crossed that bridge!) But perhaps Mr. Horner will go down in history as the guy that beat the problem 'lint.
 
  #8  
Old 05-08-03, 06:38 AM
jhorner
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Cheese... 'lint...

I think I've mustered up the courage to crack my ryobi open and start tinkering. I have no clue as how to go about disassembling it, but there's two ways this will go:

I'll screw it up and have spare parts for the next ryobi I'll buy (I assume this is a better value than switching brands),

Or I'll put it all back together successfully, whether it fixes the problem or not.

I have a love/hate relationship with this trimmer, and I've learned quite alot in fixing it. As a matter of fact, I'm beginning to form a philosophy about what drives my interest in things:

If a thing doesn't cause me a lot of grief, then it's not worth fooling with.

I'll let you know the outcome.

Jeff
 
  #9  
Old 05-08-03, 01:20 PM
jhorner
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I opened the sucker up, and I was amazed at how easy it was to get to the crank shaft.

'lint, I figured out what you meant by a stuck ring. However, that doesn't seem to be my problem. Each of them move freely enough. I also noticed the tiny little nob sticking out of the ring groove in the piston. That's where the break in the ring is supposed to go, as they don't form a full circle.

Well, I guess I should have known that I would break one of those little rings. I decided to play a bit and shoved the piston down so far into the shaft that it got stuck, and the ring broke when I had to use alot of force in pulling it out. Question? The bottom ring, meaning closest to the spark plug, is the one that broke. Can I actually run the engine without that ring? or will it explode?

Also, how do I clean the piston? I'm reluctant scrape the blow-by off with a razor blade since it seems like I'll really scratch up the piston. Can I use a solvent like mineral spirits?

I also noticed something curious on the crank shaft wall. There are two grooves, one on each side running parallel with the shaft. The piston head slides by these as it moves down towards the spark plug. It seems that if I clean those really well, then that will cause enough leakage to alleviate some compression.

So far, that's all I got. I'm off to the parts store to get some new seals, a new ring, and yet another pull cord sproket. I believe this will be number 5 or 6.

jhorner
 
  #10  
Old 05-08-03, 01:41 PM
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If you don't put that top compression ring back, the engine won't develope enough compression and it would allow a lot of blowby, in other words, it needs all the rings. Also, the piston is made of aluminium, so don't get agresive with it. Be careful while scraping it, it can be scratched easily. You can use a solvent or fine grit sand paper. Make sure to clean it well so no dirt gets in the engine.
 
  #11  
Old 05-08-03, 04:24 PM
buttlint
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Jeff,

Now ya did it, bud! We're in deep do-do now. The blind leading the blind. (hope the rest of the lads will bail our butts out)

Here is a link to a parts break down http://www.outdoordistributors.com/R...rts_Lists.html

Like mower17 said. and mineral spirits should do the job.

I emailed my address (should be in my profile anyway) if I can be of any further "assistance". But I dont really trust that it will get to you. ( I see a 4 month old email, that I never even knew was there. Sorry, Cheese, thanks for your response back then)

I would say, while you are there, check the flywheel key. But I see that you have the type of flywheel that has the key built into the flywheel. (Be careful removing and replacing that piece, its real easy to mis-align the keyway and trash it out)

Dont worry, Jeff. We will solve this kick-back problem, no matter how much time and money it costs you! If not we can hook you up with a nice new 4-mix Stihl product and ponder the problems that those will have. 'lint.
 
  #12  
Old 05-08-03, 10:00 PM
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Sheesh...I'm gonna watch this thread, but I don't know how much assistance I can be, lol. I work on quite a few 2strokes, but most of my work is riding mowers. Then, the 2 strokes I get are often higher-grade equipment. If I spen 1 hr on something like a Ryobi, I've already spent more time on it than it is worth, and I tell my customers that ahead of time. Hence, I rarely ever get into extensive repairs on these low-line products. Fuel lines and carb work are about the extent of it.
 
  #13  
Old 05-09-03, 06:31 AM
jhorner
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Yeah, it sucks!

Like I told 'lint in an email, I'm pretty close to spending the same amount on new parts as I did for the darn thing new, $75. Forget the labor!!! I've already spent more time fixing it than using it by now.

It's becoming the principle of the thing (my wife calls it hard-headed, and I don't disagree with her). I decided I would fix it myself, and by gosh I'm going to fix it!

I'm a software programmer by trade, so I always like new and challenging software problems, and the knowledge I gain from solving those problems can usually transfer to other software problems. So how can I capitalize on my knowledge of this darn ryobi?

This whole bit of a ryobi not being worth the time to fix it has got me in a real quandary. Am I just supposed to throw it away, or buy a new one and keep this one for parts? Can I become a 2 cycle engine mechanic and capitalize on my experiences fixing my own?

Lawn care _is_ big business these days, so I'd like to hear y'alls take on it....

jhorner
 
  #14  
Old 05-10-03, 01:34 AM
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It is basically a use-it-until-it-breaks machine, then you toss it and get another. However, they can be fixed a majority of the time. As to whether it is worth it, well..that depends. To me it's not, but to you, it might be. It depends on what you are trying to accomplish. If you are trying to fix it to save money, you probably won't. If you are trying to fix it to learn about it, then it may well be worth it. Knowledge is priceless, so put what you want into it, if that's your goal. I have done this before on a few things. There have been times I spent several hours on a piece of junk just because I decided it wasn't going to beat me, and I meant I WAS going to figure out what was wrong. I learned some valuable things that way.
 
  #15  
Old 05-10-03, 03:39 PM
buttlint
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Jeff,

Believe me, mechanics dislike low end machinery more than consumers do. People may think that we are making tons of money off of it, but the opposite is true. Lets use yours as an example.

If you had brought to my shop, you would have probly been quoted 40-50 bucks for the repair as an estimate. I, like many others in this buisness, am a commissioned mechanic. That means I get a certain percentage of the labor charged, let's say 50%. The total labor charge on that is 30 bucks, so that means I get 15 dollars. I shouldnt take me more than a half hour to do the job. (pretty good money, eh?)

Well, I have to guarrentee that the work I have done for the season, or I fix it for free. The company eats the parts.

Ropes usually break, because when a unit doesnt start, people believe that pulling the rope harder, will make it go. I am aware of that tendency, so I check a few things before hand, like removing the muffler and checking the cylinder for scoring. If I see the cylinder is trashed, I know that there is now way that the thing is going to run correctly, and the chances are this thing will be back the next day, with a broken rope and an irate demanding that I fix it again.

So at that point, I pack the thing up and tell the customer to come and get it, no charge. It's not worth repair. I just pissed away 15 minutes of my time and didnt make a penny. Over the course of a year, those little 15 minute periods can add up. But its all part of the game. I accept it because no money changes hands and I saved myself grief in the long run.

Now we come to your problem. It starts and runs fine (says the customer) I do my little checks and decide to go for it. I do the job and take it out to see if it starts. It does, and it runs fine, just like the customer said it did. But the customer failed to mention that it yanked his arm out of joint when he tried to start it. (How would the customer know, having nothing to compare it with? He would think it was normal.)

So thats where it sticks me. I can let it go (after all I did fix what it was brought in for) but I know damn well it will happen again. (you have been through 4 pulleys) Or I can just hope that the customer doesnt use it very often and it makes it thru the season.(not very ethical on my part!) Or I can call and tell the customer that he has this kickback problem and will eventually break the pulley again. (If I knew what caused it, we wouldnt be having this conversation) and see if he wanted it repaired. (Which puts us at that point again of cost of repair being greater than the cost of a new trimmer.

At least for you, you are getting to learn some new things. You get to satisfy your curiosity, and see how these things work. As far as your question about " can you capitalize on your new knowledge about 2 stroke engines". Well.....I kinda dont think so.

But if you do fix the problem, and tell me how you did it, you will certainly have my gratitude and admiration. 'lint.
 
  #16  
Old 05-12-03, 06:51 AM
jhorner
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Such is life...

A local lawn mower shop gave me a Ryobi 700 supreme out of their junk pile. While I was able to use it's sprocket pulley, I wasn't able to use the piston assembly; the 700r has a piston with two skinny rings, and the 700 supreme has one with 1 fat ring.

So, you may remember that I broke off one of the piston rings on my 700r. I decided to go ahead and run with out it. Results?...

Nothing has changed. It runs great, but it still strips the sprocket pulley on startup...

Next step is to take off the other ring and try it that way.

Hey, I found out that it's still under warranty. Should I try to get my money back?!?

My lawn care buddy told me to get either a shindawa or an echo. I think I'll choose the one that's more expensive and drop ryobi
forever.

jhorner
 
  #17  
Old 05-12-03, 10:48 PM
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It probably won't run at all with no rings. I doubt you'll get near enough compression. Is this trimmer direct drive, or does it have a clutch?
 
  #18  
Old 05-13-03, 09:20 AM
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'lint:

Thanks for the "insider" information on small emgine repair shops. The only point I would argue is that the 15 minutes you took without pay is not actually wasted. Rather, you are investing in a relationship with your customer.

So many places charge a non-refundable fee up front just to look at it. Then if you decide to get it fixed, that fee is treated like a credit toward labor. While I can see the value from a business perspective, it isn't the best way to forge a relationship.

The fact that you'd eat that 15 minutes would leave a lasting impression on your customers, and you'll probably see more of these folks as return customers.

-joe
 
  #19  
Old 05-13-03, 09:52 AM
Joe_F
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I guess it depends on the industry. In the appliance industry, the repairperson come to the customer, so they charge for diagnosis.

Why?

The technician's time as he/she is being paid;
The gas to get to your home;
The opportunity cost lost when you say "No thanks" when they give you a price, when they could have been at another customer's house making money on the repair;
The cost to come back since they cannot have every needed part on the truck at any given time.

etc, etc, etc.
 
  #20  
Old 05-14-03, 07:22 PM
Fyxxez
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I'm no expert by any means, but I had a similiar problem on a Homelite chainsaw. A buddy gave it to me when he got tired of puling on it. Plug in, won't hardly pull. Pull the spark plug, pulls fine. Took the housing of carefully examining it, didn't see any problems. Just dirt, noticed one of the centrifigal flywheel dogs that the puller engages when you pull it was sticking. A little silicone on it. The problem was that when you pulled it the dog was not being centrifigally throw out, because it was sticking, would not DISengage, when rpms tried to come up.
 
  #21  
Old 05-14-03, 08:06 PM
Hamerhead
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re:ryobi 700r

I bought a Ryobi (700-something or other about $70.00) last year. I had it a few months and had started it probably less than 15 times and it stripped too. I think they're hard to start because when you pull the engine rope it also turns the cutting string reel assy-this makes more load on starting. I took it back to Lowe's and the woman at the service desk said you dont havt to explain my husband had one and dozens have been brought back. I bought another Ryobi but a different model-higher price. Some guy in the store convinced me to buy it because he had one about 3 years and hadn't had any trouble with it. Also I thought if it tears up I'll just bring it back too. When you start this one, the string reel doesn't turn until you rev it up. It must have some type of clutch mechanism. If its Lowes, Home Depot or some other big outfit I would take it back there. I think my Lowe's quit carrying Ryobi.
 
  #22  
Old 05-14-03, 10:20 PM
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Hmmm...that's what I was thinking. If it is direct drive, they are bad about this. The cable and head "bounces" with the compression stroke of the engine, causing the kickback feel while pulling the rope. Try taking the trimmer head off the boom. If it starts easy, then that is the problem. A lighter trimmer head will help solve the problem.
 
  #23  
Old 05-15-03, 08:02 AM
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jhorner, you will get away without one piston ring, but not taking out two. Measure the other piston for height, and wrist pin height...if they are the same, the piston will work fine with only one fat ring.

I think the cause of your "stripping" the pulley is, as cheese said, the trimmer head being too heavy, or possibly the machine is slightly out of time. How many of you have seen a lawnmower rip the pull cord out of your hand because the key was sheared?? Same goes for 2 strokes.
 
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