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Model 917-378770
I am helping a friend repair this mower. They said it wouldnt start. When you pull start it puffs white/grey smoke and eventually throws a hard kick back but wont start.
I rebuilt the carb with a factory Craftsman rebuild kit...new gas.....but it still wont start and
throws a hard kick back...if it were a car I would say the timing was off?
By kicking I should clarify it feels like it is trying to start backwards or something as it pulls rope back hard.

2o11cb


Just wondering if there might be some gas leaking from the carburettor float, into engine oil. Just look at the oil level on the engine dip stick plug and see how much is in there and see if it smells gases.:biggrin:

Oil level was normal but I will check for gas smell in the morning. Thanks!

how does the spark plug look?

Plug looks good....but I am going to replace it just in case it

picked up new plug and oil....old oil definately smells like gas but I dont know if that was before or after the rebuild?

Changed oil and spark plugged..gapped at .030
Whats happens is that this first time it fires it pulls the the cord back towards the motor and out of your hand....almost impossible to hang on to...almost like its motor is trying to start backwards....

backwards would be a timing issue...but the cord pull could be a bad recoil assy. also......a flywheel can sometimes strip the key and throw the timing off...id pull the cooling shroud off and see if the flywheel is loose....i can help you better if you give us the motor numbers:thumbsup: .....heres a start ....Partstree.com - Genuine replacement parts for Toro, Echo, Husqvarna, Cub Cadet, Troy Bilt, Lawn Boy (Lawnboy), lawn equipment (lawn mowers, saws, blowers, trimmers, snow blowers) and Tecumseh, Kohler and Briggs and Stratton Engines. .......and.......http://www.searspartsdirect.com/par...s/Model-917378770/0247/1500600/P0202247/00001

Where can I find motor number?

usually on the valve cover...youll have to wipe it clean to see them:thumbsup:

number under cowl is
128602 0215 E1 020314 F8

ok...this is the parts breakdown ...........Parts and Diagrams for Briggs and Stratton 128602-0215-E1 ........look under blower housing and shroud and you can see the flywheel setup

fly wheel is not loose and pully string pull freely until engaging....
spring seems tor etract normally

ok...try some starting fluid....with air cleaner off...shoot it into the carb....if it takes off...its a carb problem.....if not..its an ignition issue

Thanks RedDragon I will try that after work today

no go using starting fluid...
you can pull the cord 3 or 4 times and nothing happens but on 5 or 6
it tries to start ONCE....you can feel and hear it combust but as soon as it fires it ripes backwards pulling
the cord out of your hand and then nothing.....:frown:

ok.....lets check spark ...to get it out of the way... unplug the spark plug....unscrew the spark plug then plug the wire back on.....have someone else pull the cord while you hold [with a glove] the spark plug threads to a bare spot on the engine block and look for spark [dark conditions help:smile:]....if its good well take the next step:thumbsup:

Tested plug for spark and it was very good...had friend pull cord while grounded. Without
plug in motor spun very freely....no back lash or kick....

You definitely have a sheared flywheel key if its drawing your hand back when pull starting, the only other thing that would cause that is if you were trying to start the engine without a blade on the mower. The engine is off time when the flywheel key gets sheared, just ask your buddy if he hit something and he should come clean that he did.

yes, i agree. check the flywheel key. when the rope tries breaking your hand like that- that is almost always the culprit.

this would be a good idea to pull the flywheel...you can get a puller for $10-15 bucks.....think of this as an adventure!:biggrin:....if it checks out...were back to carb.....its reassuring to the mind to be through..:thumbsup:

I have some pullers at the house from working on cars. is it just a matter
of taking off the top half of the mower? Anything I should look for(any gotcha's)
I will check the parts break down link you sent also...

just so i have a better idea of the whole thing...did your your friend hit a stump or something?.....how does the blade and blade mount look?...........when you rebuilt the carb....how did all the orfices look and the float needle...how dirty was it?...

blade looks good..fairly new and no mares.......does spin on shaft a little freely though....shaft looks straight...she didnt mention
hitting anything...said it just stopped starting....carb wasnt too dirty but she said she hadnt used it in a yr or so...cleaned all orifices and they were too bad...check float no leaks...new needle and seat and they appeared all good....it is this whole backlash thing that seems weird which is absolutely not there without the plug in and only happens as soon as it seems to hit the first firing....which is weird again it doesnt fire with starter fluid?

Pull the flywheel..
I'll bet on a sheared or partially sheared key...
Really will put a stop to pulling the starter rope... after a few of those, you become a bit leery pull starting engines... Ouch... :smile:KennyV

how long was it between the last time she ran it and it stopped starting?

The blade should not turn really free. Pull the blade and adapter off the crank and check the key on the adapter. A bad blade key will also cause the engine to act up as you discribe. The blade acts as a flywheel causing the engine to have inertia to overcome compression. If you cannot feel compression when you turn the blade by hand, then what I discribed is likely the problem

well its not like super free more like a clutch fan on car.... but I bet your right that the key broke...when you pull the cord does the fly wheel turn also or only when it actually fires...she isnt quite sure how or when it stopped working...

flywheel and blade shouldnt move separate from the crankshaft at all...if the blade is loose pull it off with the blade mount and inspect....be sure to tip the mower with the carb on the top side:thumbsup:

will do.... it is definitely moving but I thought it maybe should be clutched like that...

use the sears diagram i gave you earlier....it should definitely be rock solid to the shaft

Thanks
I wont be able to check things until Sunday but will definitely tighten and check everything over and get back to everyone

When the mower pulls the cord from your hand, the carburator has a small explosion and there is a small amount of smoke coming out from the muffler is can be caused by three things:

1. The blade is loose.

2. The flywheel key is broken. To see if it is broken you need to remove the top cover, gas tank and recoil and the nut that holds the flywheel. From here you will be able to see the flywheel and the crankshift is lined up. If its moved a little bit the key is broken. Replace it. If everything is lined up here. Put everthing back together. You can buy a key at any sears hardware for about $2.

3. Next 7.0 hp is overhead valve. So you would need to remove the front valve cover, where the lifters are found. Check for a loose lifter.

Hope this helps solve your problem.

So I tightened the blade..there is a space/mounting piece and the bolt just wasnt tight enough but that didnt solve anything...though the lower key and shaft looked fine....
as I tried to start it..it is definitely internal. pulls fine a couple times until firing then kicks back...
this time it tried to start every time but kicked/pulled back every time and died....
it has to be a flywheel issue or valve issue...cant work on it until Wed...
I will tear the top side down and see whats up then....

pulled valve cover and springs, rockers, and rods all perform ok...
pulled recoil for starter rope and housing off...didnt see a problem everything moved feely...do I need to take the big bolt off and actually separate the pulling gear from the fly wheel...

yes...you may be able to see the key after you take the bolt out

will do when I get home...
whats the best way to lock that flywheel while I am trying to loosen the bolt?

Pulled flywheel cover and key is broke...flywheel has moved by 1 in. on shaft... which is throwing timing off I assume and causing the kick back...have to get puller now and new key....I will let you know how things proceed.

GREAT TO HEAR !...YOU FOUND IT!....REMEMBER TO GET YOUR VALVES BACK TOGETHER AND ADJUSTED PROPERLY!....USE A NEW VALVE COVER GASKET [ I ALSO USE A THIN FILM OF HIGH TEMP -RED- SILICONE ]......KEEP US UPDATED! :thumbsup:

I dont have a Sears store close by and looking for the key to order through Sears online I only see the entire engine as a part number? Do have a link to ordering the key?

ah..nevermind found it at parts tree

argh! pulling hair out now...replaced key and put mower back together....it started an ran for about 10 secs....then stopped....now it appears I have no spark....frustrating to say the least...

how did it run for that 10 seconds?

it seemed like it was going to run fine and then just died....I checked and now there is no spark..

the magneto picks up signal from the flywheel....maybe it was damaged

thanks again and well I was hoping it was something else....does it normally just die like that?

without more info.....it sounds like ignition quit...but check to see if fuel is in the carb bowl

yepper fuel in bowl....checked during darkness and absolutley no spark....I even disconnected the safety kill ground wire and tested....I can only assume the magneto just died too...wow....but ****
everything will be brand new when I am done....there is no flywheel timing adjustement I could have missed right....I am pretty good with cars and mechanics....the flywheel and key appear to only go on one way and it appears there is no adjustment to the magneto other than the mounting bolts which I didnt ouch until after I wasnt getting spark?

did you check the gap for the magneto?....the flywheel may have settled after the 10 seconds...it a longshot but possible.....was the flywheel nice and tight after the key replacement and is it tight now?....dont get discouraged.....its something basic....take a deep breath and go over everything you just worked on :thumbsup:

Thanks for all the help.....what should the gap be? I was thinking about a gap like in old point/magneto distributors when I loosened it to check after it died and gave no spark. I guess I need to get the old feeler gage? I havent had one in a few yrs or is there some old trick like match books?
Everything seemed tight still but I will
recheck everything tomorrow...:biggrin:

http://www.hammerwall.com/Download_Manual/5384/ enter the scrambled letters and them click download.......i trying to find the gap specs......how did you find no spark....you pulled the plug and grounded the threads or?

I always use an old business card to set the gap. Works fine. If the flywheel nut was not tight enough, you may have sheared the key again.

replaced magneto with new one and gapped with card included....still wont start....checked flywheel and key is good....starting fluid doesnt help....only getting a puff or two of white smoke....regapped spark plug to .020 like manual said....

ok I might be brain damaged...I looked over the carb and noticed moving the throttle actually doesnt change anythig on the carb...

Hey hey....Its running BUT
ok so here is part of the deal.....this is a no adjust carb.....and the blade has a blade adapter peice on it....took out the air rachet and cranked that on!
now it is starting but runing like a bat out of hell and the choke spring and armiture dont seem to be doing anything....
almost there though
I did replace the fuel line with some older fuel line that higher a slightly higher diameter....could that effect anything....

ok just mowed for a few minutes ....IT is a 7hp and maybe it is running
as should but it does have a throttle control which isnt doing anything and I have a new cable on it.....
as you can see this has been a mission for me
But when I let off the handle and kill it ...it wont restart for say 10 minutes or until it cools down...

ive had these magnetos die when they get hot....in fact ive replaced 3 of them this year...when it dies it has no spark?

well it is strange I can run it for 1 or 2 min and stop..then it wont start but I also noticed the blade is coming loose every single time...going to go get a new bolt and lock washer...the one on there is
worn to a curve almost....Probably needs the real blade too instead of the adapter peice...

and use a couple drops of locktite :smile:

2011cb said:

Model 917-378770
I am helping a friend repair this mower. They said it wouldnt start. When you pull start it puffs white/grey smoke and eventually throws a hard kick back but wont start.
I rebuilt the carb with a factory Craftsman rebuild kit...new gas.....but it still wont start and
throws a hard kick back...if it were a car I would say the timing was off?
By kicking I should clarify it feels like it is trying to start backwards or something as it pulls rope back hard.

Click to expand...

i would say by the sounds of things is timuing or air filter plugged fly key may be damaged top likely

2011cb said:

Hey hey....Its running BUT
ok so here is part of the deal.....this is a no adjust carb.....and the blade has a blade adapter peice on it....took out the air rachet and cranked that on!
now it is starting but runing like a bat out of hell and the choke spring and armiture dont seem to be doing anything....
almost there though
I did replace the fuel line with some older fuel line that higher a slightly higher diameter....could that effect anything....

ok just mowed for a few minutes ....IT is a 7hp and maybe it is running
as should but it does have a throttle control which isnt doing anything and I have a new cable on it.....
as you can see this has been a mission for me
But when I let off the handle and kill it ...it wont restart for say 10 minutes or until it cools down...

Click to expand...

running to fast check rpms 32 hundred

Hello again
So I replaced magneto but it still wont start a second time if you let it run for more than 10 secs....
also are there any clear diagrams of the chock spring setup...the throttle doesnt change the engine
speed not even if you adjust the lever manually?

this thing's turned into a real pain in the ***:frown:.....can you take pictures of the throttle linkage?.....and blade adapter too....somethings goofy here.... and it would be easier to diagnose with pictures:smile:

you can say that again....and hell its not even mine.....
I sure can...tomorrow afternoon so I can get some good light...Thanks!