Can't start my 92cc saw

[Bedford T]

I have a ms660 kit that has been detailed here in forum and its ran great, trouble is i can not get it to crank and was wondering if you would be willing to help. here are the things i have done. building the kit was an education i would have never gotten this far without the hands on experience and the people i met.

The saw ran great and idled perfectly for about 1 1/2hrs. I shut it off and put away. the next day it would not start. total hours on saw, maybe 10.

i have been working at it for two days trying to determine what is wrong. I do not have extra parts where i can swap and troubleshoot and actually that has not been needed so far. this is what i have done and if you can help me out i would appreciate it. no chance of flooding and just to be sure from time to time I just held the throttle wide open and pull till i was blue in face and i would move on.

the spark was checked with a light between the plug and the coil and seems to be fine. not convinced and to exclude the spark plug as well, i laid the plug on top of the jug and took it in a dark place in my basement where i could see it and i had hot fire coming from the plug. plug is new

for the air, the filter is newish and clean and the carb shutters are operating properly and open to the correct position with the controls.

for the fuel i took the carb off and checked the jet it was clear and the area was clean. i took a small piece of hose and connected it to inlet and blew and fuel came out. fuel came gushing out when carb was disconnected so the line and filter are good. I took starter fluid w/oil and with the throttle ...on run... it would not crank. today i tried mixed fuel and it would not run. or make any combustion noises either time. the impulse line was replaced because it was not oem and i was desperate and it had no effect. the one i took off was perfect and tight.

flywheel is tight. I took a stop and wedged the piston, flywheel would not move. so much compression I have to use the decomp to pull starter.

what could it be? thanks in advance

 

[alexcagle]

Pull the plug.
Is it wet?
If you've been cranking away, it should be.
Go ahead and replace it with a new one.
*
Check the piston at Top dead center that the magnets on the flywheel lead the coil about 3/4" - 1" counterclockwise. If it's way off, then pull the flywheel and check the keyway, that it's not sheared. Just because it's tight doesn't mean it's not sheared.
*
If that's good, check the piston by removing the muffler.

 

[grack]

Did you pull the muffler just in case or do a compression check. A guy brought me a fresh rebuilt 288 with chinese rings that had worn out after little use.

 

[blsnelling]

1. Check compression and condition of P&C FIRST.
2. Check the flywheel key.
3. Is it getting fuel? Is it getting too much fuel? Replace the carb with a known good one.
4. Replace the coil.

There's really nothing else involved.

 

[alexcagle]

*
In the OP, He said he has to use the deco to pull it over because of tremendous compression, so the compression sounds very good. If a seal is damaged or has popped out, the primary compression can suffer enough to cause the saw to "not start".
*

for the fuel i took the carb off and checked the jet it was clear and the area was clean. i took a small piece of hose and connected it to inlet and blew and fuel came out. fuel came gushing out when carb was disconnected so the line and filter are good.

*
Exactly what do you mean?
Fuel came out of what when you blew into the inlet?
The jet, with a hose pressed against the High Speed circuit feed hole? -or the actual nipple that the fuel hose connects to with the carb buttoned up,(assembled)?
*
Did you try pulling the saw over with the plug removed? If so was there spray?
*
If the plug was dry when you pulled it, where exactly did you put the fuel to try to prime it? (carb or spark plug hole)
*
One thing to check is to pour the fuel out into a clear bowl and look for water on the bottom or cloudiness in the fuel.

 

[Bedford T]

i was burning leaves and i got the fire dept excited and the 4 trucks and 20 people just left. so i had to stay with them.

Exactly what do you mean?
Fuel came out of what when you blew into the inlet?
The jet, with a hose pressed against the High Speed circuit feed hole? -or the actual nipple that the fuel hose connects to with the carb buttoned up,(assembled)?

i put a hose on the carb inlet where the hose goes that comes from the fuel tank. i did that while i was checking the jet. the cover was...unbuttoned.

Pull the plug.
Is it wet?
If you've been cranking away, it should be.
Go ahead and replace it with a new one.
*

i did replace the plug. the plug has been in and out while testing and its been wet depending on how many times i have tired to crank it. i checked the plug by laying it on the cylinder head and pulling it in the dark where i could see the spark. spark look hot and plenty of it. i used a testing light inbetween the plug and the coil and it looked right.

Did you try pulling the saw over with the plug removed? If so was there spray?

spray where. i did it in the dark and i did not know to look for spray. that might be hard to impossible for one guy to see its so hard to pull.

If the plug was dry when you pulled it, where exactly did you put the fuel to try to prime it? (carb or spark plug hole)

first i used a starter fluid that has oil in it and sprayed in the spark plug hole the next day i used an eye dropper and put motomix fuel down the spark plug.

One thing to check is to pour the fuel out into a clear bowl and look for water on the bottom or cloudiness in the fuel.

checked, my mix is 92octanne fresh one week old fuel mixed with the proper amount of oil, came from a very busy pump where i know the guys changes his filters. today i emptied it and used motomix.

i know that there is very little to it but thats just the problem the things you check are checking out so it does not make sense. i am not experienced but i can tell you this. i can read and follow instructions and the details i have provided are accurate. so this does not make sense.

now to the part i do not understand the timing is suspect now and you have provided instructions could we go over those a little bit so i better understand. i would like to make one point thats is confusing me. if i put stater fluid down the spark plug hole and use a plug that minutes before glowed while the starter was pulled but does not combust when the plug is inserted and tighted and and the started is yanked about 5 times with the control in the run position. it looks like it would have "hot burbled" once. i am getting nothing but plenty of compression when pulling.

 

[Bedford T]

Check the piston at Top dead center that the magnets on the flywheel lead the coil about 3/4" - 1" counterclockwise. If it's way off, then pull the flywheel and check the keyway, that it's not sheared. Just because it's tight doesn't mean it's not sheared.

do you mean pull the plug and the side cover and check to make sure the magnets line up close with the top mark when the piston is at the top of the cylinder by looking down the spark hole and then check the mark..like installing it?

 

[Bedford T]

Did you pull the muffler just in case or do a compression check. A guy brought me a fresh rebuilt 288 with chinese rings that had worn out after little use.

you can hold the saw by the handle and it will take a very very slow ride down. you can not pull the starter without using the decomp or it will snatch the handle out of your hand.

 

[Bedford T]

i would feel better about it if my attempts had given me some burble on the assisted starts when i used the starting fluid. i have ordered extras and it will be a week before anything one thing gets here. i looked closely at the the jug and piston and it looks good rides up and down, color is good. it worked perfectly, it idled perfectly and when i turned it off it was unremarkable. it did not jump all around when it was idling and it would idle as long as i needed it to and when i was in a cut it was a very hard worker. it is fairly new and had been setup to run a little rich and my oil in the last batch i mixed was mixed at 40:1 so it had plenty of good lubrication.

1. Check compression and condition of P&C FIRST.
2. Check the flywheel key.
3. Is it getting fuel? Is it getting too much fuel? Replace the carb with a known good one.
4. Replace the coil.

There's really nothing else involved.

 

[Bedford T]

In the OP, He said he has to use the deco to pull it over because of tremendous compression, so the compression sounds very good. If a seal is damaged or has popped out, the primary compression can suffer enough to cause the saw to "not start".

i will keep this in mind and see if i can get someone to do a pressure vac test if needed. no oil is showing up in those areas. and it looks like some would seep through or i would have had some indication in its ability to idle well. anything is possible.

it might be the coil when put to use flakes out. also could be the carb. but i bypassed the carb using the starter fluid

 

[alexcagle]

do you mean pull the plug and the side cover and check to make sure the magnets line up close with the top mark when the piston is at the top of the cylinder by looking down the spark hole and then check the mark..like installing it?

*
With the plug out, just put a pencil in the spark plug hole, eraser end on the center of the piston, or something similar. I realize on an ms660 it's at an angle.
Then take the starter off.
Then rotate the flywheel counterclockwise until you are at the top, then look at the central point between the flywheel magnets in relation to the center of the two coil legs. It should be about an inch difference about (26 degrees) ahead of the coil.
Usually if it has slid on the keyway it will backfire once in a while out of the muffler, but not always.

 

[Mad Professor]

Bad decomp valve?

My 066 had one that would stick open since nearly day one.

I just stopped using it and it starts up fine.

 

[alexcagle]

I've seen new Bosch spark plugs be bad right out of the box. It's very rare, but still.
*
The fact that it's yanking the handle out of your hand lends creedence to a timing issue. Might be firing on the way up.
Does yours have an elastostart pull rope on it?
I have ran quite a few 660's. They've got good compression, but not brutal compression like the old 1960's West Bend 10hp 820's, or my old AH81 with 134cc's.
*
If it's out of time bad, it's not going to start, or try. The OEM coils actually retard the timing a bit at low RPM, and ramp up in the mid and high RPM.

 

[Bedford T]

Yes sir I put a elastostart on it.

I understand what I need to do next. you made it clear for me.

I am using a NGK plug and will replace it again just to be safe.

I will look at it tomorrow it dark here now and I am beat. Thanks for your help I will report back tomorrow.

 

[alexcagle]

The spray to look for is with plug pulled out and starter yanked on a few times with the throttle wide open, and the choke open. The spray I'm talking about is out of the spark plug hole. A Ziptie on the throttle makes it easier, but don't try starting it like that though.
Pull slower at first, because if there's a bunch in there, you might belch it out on you or something flammable nearby.
If it does spray out, then tilt the saw back slowly with the piston at top dead center, the fuel in the crankcase will run out of the carb throat.
If the crankcase is full of fuel, it can also cause partial hydraulic lock, depending on the amount in there. That might explain the excess compression you are experiencing.
If this is what has happened, then you have a leak in the carburetor.

 

[TBS]

It wouldn't hurt to check the needle valve lever in the carburetor. I had a new carb on an 017 that after running a few times started flooding because the needle lever was set to high. It took forever find out that was the issue.

 

[Daserlon]

Just being a smartash. Get an all orange 94cc and be happy. My 394 eats my friends 660.

 

[Big_Wood]

is this the AM saw with the OEM badge? it's cursed, swapping the AM badge back on might bring it back. anything OEM on it could be messing it up.







hutzl coils suck .....

 

[weimedog]

Dang, a new saw with an issue. Should bring it back to the dealer where there is expertise to fix that saw; on warrantee. With parts if they need for those warrantee issues.

 

[grack]

Figure it out yet.