Jump to content

Garden Tractors and Parts on eBay

- - - - -

Massey Mf1650 Kohler K341 Engine Rotation/gear Timing Help

  • Please log in to reply
5 replies to this topic

#1 quietwnd OFFLINE  

  • Member
  • Member No: 10863
  • 0 Thanks
  • 6 posts

Posted August 15, 2012 - 12:35 PM

1) Engine won't start, starter DOA, improvised rope "pull start" on front crank hub, confirmed ignition spark
2) checked fuel supply and delivery (normal)
3) starter rotation specifies CCW rotation, engine rotation should be clockwise (looking front to rear/ flywheel back, starter upper left of flywheel housing) but with head removed valve sequence definately appears wonky....
4) low "intake" fuel vacuum but noted definate compression.

Found timing mark on camshaft gear, "cam gear" mark aligned with crank timing mark closest to gear end on crankshaft front with piston postion at TDC, noted valve overlap occuring with plus or minus 5 degrees rotation???? Thought valves should be closed on ignition sequence,

Cam timing appears 180 degrees out of sync with side gear cover removed for inspection. Valve adjustments verified correct, adjustments made at point "both" cam lobes positioned "down"!
Counter balance gears have two timing marks.. one "dot" dimmple, one "arrow" pointer, I note upper & lower counter balance gears synchronized in relative position to eachother and found dimmple on lower counter balance gear aligns with crank timing mark nearest front gear on crank with piston position near bottom of piston stroke. (lower counter balance gear seems to have dimmple aligned with timing mark clooset to front on crankshaft) seemingly correct, also by appearnce lower and upper counter gears have same relative positioning means syncronized in positioned unison!
Didn't yet pull front bearing cover to check timing marks on upper counter gear.

Confused on three crankshaft reference marks to correctlly specify "Standard", "Primary", and "Secondary" timing marks! I only found two..... my reference as I see on crank is thought to be primary mark closest to gear and secondary mark closest to, "on" crank journal shoulder!

Conclude if correct secondary timing mark on lower counter gear" supposed" apparently is dimmple on wider side of counter balance gear.Manual specifies" SECONDARY TIMING MARK on LOWER "COUNTER GEAR" will align with "STANDARD" timing mark on crank when fullly installed if timed correctly, If this is correct it looks as though counter balance gear is factly timed correct looking at aligned mark closest to front gear on crankshaft

Removed head for valve/ cylinder inspection : appearance good, suspect recent rebuild but brief run only!
Moderate carbon traces at intake valve but appeared may have been backfiring, unconfirmed last "running state".

Going by presumed clockwise rotation on front pulley; valve operation appears backwards! I noted using clockwise engine rotation intake valve opening on "up" stroke (wtf), exhaust valve opening on "down" stroke! again (wtf)!!!!!

Rotated engine crank counter clockwise on front hub pully(opposite flywheel), valve sequence now appears normal as intake opens on down stroke, exhaust opens on up stroke,

4 cycle theory applies "Intake" ( valve opens on down stroke) , "Compression" valves closed through upstroke, "Power" ignition occurs (BTDC),valves remain closed on down stroke, "Exhaust" valve opens near bottom stroke forcing spent gas on upstroke. cycle repeats, Result would be running success.....

I somehow believe I need to rotate cam 180 degrees or cam gear becuase what I see to be fact crank and cam gear marks are aligned when piston is at TDC but if I slightly rotate "before" TDC and observe for point opening (ignition pulse) exhaust valve is definately "open" not closed as should be expected! With piston at TDC with cam and crank marks aligned exhaust valve is sliightly open.

I am going to readjust valves with cam lobes facing fully down and see what happens using spec (.008 intake), (.019 exhaust) would have thought cam lobes would be faced away from cam lifter when ignition occurs..... I will post update as soon as I find the cause, and while I have it open I will take pictures and their position timing marks since b&w low resolution pictures are worth diddley....lol

If you recognize something I am obviously overlooking I would appreciate and respect your knowledge just the same!!!

#2 WNYTractorTinkerer OFFLINE  


    Tinker Master

  • Senior Member
  • -GTt Supporter-
  • Member No: 10789
  • 17594 Thanks
  • 7629 posts
  • Location: Avon, NY

Posted August 15, 2012 - 01:26 PM

  • Everything you need to know about that engine is in here- D/L and save it to your H/D:

BTW the crankshaft rotates twice for every Cam revolution so it may appear to be 180 degrees off but it isn't.. It's a 4 stroke..

Edited by WNYTractorTinkerer, August 15, 2012 - 01:28 PM.

  • quietwnd said thank you

#3 quietwnd OFFLINE  

  • Member
  • Member No: 10863
  • 0 Thanks
  • 6 posts

Posted August 15, 2012 - 04:33 PM

I was aware it's a 4 storke, I outlined the sequence's too hahahaha

I did check valve adjustment and all was good. Thought I might check ACR calibration... according to the manual you posted I unfortunately didn't have that section available when I plunged into this motor !

Should have specified it was not running when I got it, part basket case per say with DOA starter. Not equipped with recoil starting means!
Out came the improvised starting aid! Typically recoil on blower housing turns clockwise on most engines so I improvised rope start off the front pulley!

I am leaning heavily on correct engine rotation cause what I found in the manual you posted was mention on setting Auto Compression Release, it says to check setting turning engine clockwise from flywheel on compreession stroke.....Interesting but made sense since starter is suppose to turn counter clockwise that would indicate crank rotates clockwise from the drivers seat/"flywheel side". Front side pulley which I added my improvised recoil rope would have to turn counter clockwise(opposite flywheel)! If that makes sense, I will be trying to reverse my recoil off the front pulley (below my exhaust) and it appears it will fall into the correct sequence I understood I wanted to have in the first place.....

ccw starter = cw flywheel > ccw front pulley = (test result normal valve sequence operation!) Doesn't show any recoil start apparatus attached but I'm very confident that should be the answer because spec reference for starter rotation is from drivers seat, The hypothesis is ccw starter rotation means clockwise crank revolution from the seat/flywheel side! Thats contrary to most engines turning clockwise off the front pulley! Obvious now I need to crank counter clockwise off front pulley since I struggled for a couple hours trying clockwise start at front(no wonder everything looked messed up!

Me owes you a heap of thank for that one paragraph reference ACR!!! :smilewink:

i think I can have it going in about 15 minutes once I dunk the oil pan back on! :dancingbanana: .

#4 JDBrian OFFLINE  


    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9679 Thanks
  • 14162 posts
  • Location: Hubley, Nova Scotia - Canada

Posted August 15, 2012 - 04:44 PM

I was just going to post that it should be CCW when facing the crankshaft.

#5 quietwnd OFFLINE  

  • Member
  • Member No: 10863
  • 0 Thanks
  • 6 posts

Posted August 15, 2012 - 05:50 PM

That's the answer to confirm my theory... so K
Oversight on my part initially!!!

I will be hoisting a few shots of Crown Royal in your direction for special thanks! It will still be great reward for the purchase price with attachments.

I wanted to do full paint restore anyway....

Thanks again, we be rollin tonight

#6 quietwnd OFFLINE  

  • Member
  • Member No: 10863
  • 0 Thanks
  • 6 posts

Posted August 15, 2012 - 09:23 PM

:thumbs: It runs, drives, and hydraulics work! Need to tweak the carburetor a touch with some new cables she be good like new!

Changed recoil direction, all is good! :laughingteeth: Counter clockwise (manual start off the front worked perfect!