Stihl 084 starter kick back

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A few years back I was occasionally getting bit by my 084 , my 288,and my 2101xp. I saw a ski-doo
starter (d- handle) on flea bay for maybe 4-5 bucks and put one on each of them .Sure does save
arthritic hands. I didn't know there were OEM d- handles.
 
My 290 was doing the same thing, it was acting like it was trying to vapor lock. I ran some VP fix-it fuel in it and let it sit overnight, It' pulls easy now and starts like it did when it was new. Not sure if that will help but it can't hurt anything.
 
Update - new coil appears to have resolved kick back at start up. Easy to start and seemed to run well at wot, but an ongoing issue worsened quickly - mid-range throttle very erratic and unstable. Very limited runnng to prevent engine damage. Pressure and vacuum testing - manifold has a crack - looking for additional leaks.
Robin, I think you're right - appears saw does not like me very much.
 
Main leak - pulse line broken at the bend off tip of the niple at the body.
Appears, manifold boot 1124 141 2200 has been updated to 1124 141 2201 and is available for about $60. Is there a product that would successfully repair a rubber manifold boot - maybe with spray coating that would seal leak and withstand gasoline and oil?
 
Advertisements for Flex Seal Spray Rubber Sealant Coating make you wonder. Flexible, chemical bonding agent to rubber - just a thought.
 
Two things you may want to check, it can be either jumping time at the flywheel or the carb may need rebuilt because it’s dosing the fuel at too high of a rate and hydro locking the engine. Have you tried rebuilding the carb? How much torque are you putting on the flywheel, and are you sure all the mating surfaces are clean between the crank and flywheel?


Thanks for the feedback. Answers :
1) Best I can tell - woodruff key, slot in crankshaft and flywheel appear perfect. Flywheel only has one slot.
2) Coil Bosch - 2 204 222 114 - I worked with local Stihl dealer in 2011, when I selected and installed these parts. I understood this coil to be same as 1124 400 1305.
3) No hydraulic lock or flooding.

Additional info - no kick back until maybe a year ago. Began very rare - now it's almost every pull. Can't express how violent kick back is. I use heavy leather gloves when attempting to cranking it. I have enough hand grip that the Stihl rope grip / handle folded as rope pulled it between fingers.
Rope is about 40" long. If I pull rope slowly to full length, kick back only occurs first time piston goes thru tdc.

Could a bad coil or trigger be the cause ?
thin
 
Thanks for the feedback. Update:
1. Pressure/vacuum issue:
A) manifold boot - crack not completely through the rubber, but repaired/sealed with super glue, as suggested.
B) replaced impulse line.
No leaks - holds 7psi (p & v) for one minute with no detectable movement of guage needle.

2. Kick back at start up appears resolved -has not happened with new coil. Saw cranks and runs well at high rpm.

3. Saw will only run couple seconds at below full throttle. Carb vacuum tested well, but replaced gaskets, pump and metering anyway. No improvement. Removed welch to check ports - all clean as could be.

Waiting for new welch plug and additional ideas.
 
No, the spring felt good. I adjusted the lever slightly, set it perfectly level.

Saw had shown very minor symptoms of this issue for several months, just worsened suddenly, to point it's not usable. Interesting, up until now, it would idle for minutes - running just not stable at partial throttle.
 
Thanks. I'll start search for a coil, and check for carbon. I think a person would have to experience the kick back to believe the magnitude.

My 084 has grabbed me a few times. I remember each one of them[emoji1787]


Sent from my iPhone using Tapatalk
 
No, the spring felt good. I adjusted the lever slightly, set it perfectly level.

Saw had shown very minor symptoms of this issue for several months, just worsened suddenly, to point it's not usable. Interesting, up until now, it would idle for minutes - running just not stable at partial throttle.

Swap back to the old coil and test it out again to be sure
 
Re trying old coil - I think I'll pass - I'm probably lucky to still have my arm. I can relate to "Grabbed". One day, determined to crank it, I counted over twenty consecutive kick backs. I have a fairly strong grip, but learned that was not a good idea - one kick back pulled the "T" handle between my middle fingers, folding original handle to "V". Ended day with broken pull cord.

Re valve jet - Stihl tech gave me part number 1124-121-5403 - ordered it today.
I asked tech if there was a way to test a valve - pressure/vacuum test from venturI end. Mine has no restriction either direction .
 
Re trying old coil - I think I'll pass - I'm probably lucky to still have my arm. I can relate to "Grabbed". One day, determined to crank it, I counted over twenty consecutive kick backs. I have a fairly strong grip, but learned that was not a good idea - one kick back pulled the "T" handle between my middle fingers, folding original handle to "V". Ended day with broken pull cord.

Re valve jet - Stihl tech gave me part number 1124-121-5403 - ordered it today.
I asked tech if there was a way to test a valve - pressure/vacuum test from venturI end. Mine has no restriction either direction .

If you are talking about the nozzle check valve, it is a one way device. It should let fuel through it into the venturi of the carb when running at full throttle but should seal and not let air back through it when not at full throttle. Any air being sucked back through it will lean out the mixture in the low speed circuit and make it hard to get a consistent idle as well as screwing up the "return-to-idle" after full throttle. These valves consist of a small caged rubber disc blocking a fuel orifice and the disc often gets deformed by alcohol in the fuel and won't seal (sticks wide open). Another favorite way to destroy them is to blow out the main jet with high pressure air and inadvertently blow out the disc.
 
Thanks, Old2stroke - best explanation I've gotten re the function of that valve. Also, your description of how the saw would run with open valve is exactly what the saw was doing. I've not taken the valve apart yet to see what's inside, but a thin piece of clear plastic is exposed, with what appesrs to be a piece of foam above it.
 

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