QuestionQUESTION: Hi Ben! Thanks for taking my question. I have the engine mentioned above mounted on a log splitter. If the engine is warm it will start with the throttle on low (butterfly at rest). If I try and start it cold the only way I can get it to fire is to open the throttle a little. Upon doing this and I get it to fire I'm liable to lose my fingers from a severe kick back! Ive rebuilt the carb, checked the key and keyway and flywheel. I also replaced the coil as I was having trouble with the engine dying after being warm. If the problem is related to a decompression valve why would it not act that way at low throttle firing and act that way at partial open? It screems carb to me but I'm not sure how to adjust spring tension and mixture screws for correct setup. Am I correct that mix screws adjust the amount of air mixing with the fuel? Unscrewing creates a more lean condition? When running and I give it throttle and the butterfly opens wide and the engine acts like it is either loading up with gas or starving for gas then gets its legs under it and runs ok. Some help would be greatly appreciated for sure!
Thanks in advance.
Robb
ANSWER: Robb
These engines had allot of problems with kickback.
I was into a HM100 with electronic ignition awhile back and the kickback was so bad could hardly even pull it through the compression stroke with the ignition wire removed from the spark plug! I finally pulled the head after checking valve lash, etc and it had about 1/8 inch of carbon build-up in the head and some on the piston! This engine did not have very many running hours and did not burn oil! It was stored with sta-bil in the gas over the years and most of time when it was ran it burned 4 gallons or more of gas that had stabilizers added and got run very little on raw gas! (I'm assuming that the oil's in the stabilizers was the cause of the carbon build-up)
You might also check the spark with a spark tester to see that it is good a strong. A weak spark can cause kickback. You may also want to check the small spring on the MCR to see if it is broken. You will have to to pull cam to see it. As far as the mixing screws yes they set the amount of fuel & air for the intake,The initial adjustments on the carb are as follows. The main jet in the bottom of the carb bowl should be set to 1 1/2 turn open from lightly seated. The idle needle on the side of the carb should be 1 turn open from lightly seated. This should get you started and running provided you have no other problems. The final adjustments are performed after the engine has reached operating temperature. Run the engine at full throttle and turn the main needle in until engine runs erratic and note position then turn out until engine runs erratic and note position. Turn the screw back in midway between the two points.
Return the engine to idle and repeat this process with the idle jet. If the engine hesitates when going from idle to full speed when accelerating quickly then adjust the main jet with engine under a load 1/8 a turn at a time until it accelerates smoothly.
---------- FOLLOW-UP ----------
QUESTION: Hi Ben,
I'm in the process of replacing the flywheel key just to make sure. It looks ok but another guy on another site said it straightened his kickback problem out. I'm still baffled on why it wouldnt kick back on me at all-ever when warm and the throttle on slow speed but if given any throttle at all to start it (cold) it wants to kill me!! I before I go to the extent of tearing it down to check valve lash and compression release I may try and put a light spring to resist the vacuum openning the butterfly so quickly when it does fire. I bought this log splitter used from an old farmer who constructed it himself so I dont know exactly what this engine looked like stock as far as springs and rods working around the throttle-carb-governor assembly. What a pain in the rear. Thanks for your help so far Ben!
ANSWER: Robb
Hopefully you get this fixed
---------- FOLLOW-UP ----------
QUESTION: Ben,
Does the about followup question hint to anything to you? Any idea why it wouldnt kick back on slow throttle but would on increased throttle?
AnswerRob
it probably has something to do with the magnets and the revolutions when the engines spins at a certain RPM it starts the process of powering up the coil to fire so as it is spinning it gets past that weak spot you may have a bad magnet also. Some have magnets that can be replaced.
