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2019/11/23 09:53:26
Jon A

Hard pull when starting Predator engine

Hi, This is my first post on this forum.  My problem is with my generator with a manual start Predator 420 engine (R420 III) (A1412015080).  There seems to be so much compression that I cannot move the pull cord thru the compression stroke.  this happens when the motor is both hot and cold.  It will take the cord right out of my hand.  The generator is new and has only 20 hours of running and did not do this when the unit was first used.  I do not know if it has any type of compression release.    Any suggestions on how to resolve this would be appreciated.  Thx, Jon
8 comments Leave a comment
AVB
One of three things it can be. Either valve clearance are excessive disabling the ACR or the ACR on the camshaft has failed. OR if the valve clearancce(s) are too great due to the engine dropped a push rod.
 
Intake 0.004" - 0.006"
Exhaust 0.006" - 0.008"
 
ACR = Automatic Compression Release
2019/11/23 10:08:59
Jon A
AVB
One of three things it can be. Either valve clearance are excessive disabling the ACR or the ACR on the camshaft has failed. OR if the valve are too great the engine dropped a push rod.
 
Intake 0.004" - 0.006"
Exhaust 0.006" - 0.008"
 
ACR = Automatic Compression Release




2019/11/24 08:09:37
Jon A
So I found both valves slightly out of spec and adjusted with the engine a few degrees beyond TDC but the compression lock remained.  The valves open and close normally but if I rotate the engine by hand I cannot see any movement of the rocker arms as the engine comes up on TDC. If the ACR is operating properly shouldn't I see a valve open slightly when I turn it over by hand?  Is there any other things to check before I open everything up to examine the ACR?
Thx,
Jon
2019/11/24 16:25:27
AVB
Yes one of the valve should open monetarily just before TDC compression. It would be a great lot of movement but you should be able to feel it and see it move.
2019/11/24 17:25:32
Jon A
So I got the engine/generator assembly out of the frame today and onto my bench but I cannot figure out how to separate the generator from the engine so that I can open up the engine and take a look at the ACR.  Does the side of the crankcase come off with the generator?  Do I have to disassemble the generator to get it off?  I cannot find a setscrew or any other way to separate the shafts and I am not going to beat on anything until I figure out how went together.  Any suggestions would be appreciated.
Thx,
Jon
2019/11/26 16:39:48
AVB
You need to disassembly the generator alternator. First by removing the outer field assembly and then the rotor. These rotors are generally held by one long screw [bolt]. The rotor held on to the engine crankshaft tapered end. Some rotors have a puller bolt available to force the rotor off the taper. Others the long screw is loosen but not removed and using a heavy hammer much like handheld sledge hammer with a block of wood up against side of the rotor. You hit the wood block to shock the rotor loose. Just got to be careful hitting the wood block and not the rotor itself during this time. Don't this with the retaining fully removed either as the rotor is very heavy and can fall off and get damage or hurt yourself.
 
From there it should easily removed and the engine disassemble.
2019/11/26 18:00:53
Jon A
Thanks.  I appreciate this information and I'll get it apart tomorrow.  
 
Jon
2019/11/26 21:27:38
Jon A
 
Success.  I got everything apart and found bits of hard black plastic in the crankcase and one little bit jammed in the ACR, preventing the spring from returning the pin to the stopped position.  I cleaned everything up and could not find where this plastic came from.  The only plastic piece in the crankcase is the low oil level sensor and that was intact.  So I buttoned everything up and it ran well for a half an hour test.    Harbor Freight offers little in tech support for this generator and I was told that parts are no longer available even though this unit is only about 3 years old!  Might be a reason to pay the extra  money for a Honda next time.  Thanks for your help.  
 
Jon 
2019/11/30 11:40:50

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