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MF8 Tecumseh timing problem


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#1 1badMF OFFLINE  

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Posted June 14, 2011 - 12:27 AM

Well i finally got a chance to play with my massey after staring @ it for 3 months while the other projects got cleaned up. I cleaned the Carb. Put new brushes in the starter. It popped right off, but barely responded to throttle position. after tinkering with the carb for awhile it would only hit about 40% rpm with violent pops out the exhaust, I mean violent!, and no power. I decided pull the head to check Ign. timing and glance at cam timing. Cam timing looks to be good. but ign timing is .300" ATDC! How is that possible. The guy i bought it from said he replaced the short block (used the original flywheel and stator plate on the new engine) is there different stators for the 8hp tecumseh? I dont have enough room to adjust the plate and the lobe is fixed on the crank. I am not a master mechanic but I do have a strong background with small engines, although I am brand new to tecumseh. any Ideas?

#2 1badMF OFFLINE  

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Posted June 14, 2011 - 12:17 PM

Looks like it has the 3amp A.C. charging system.

#3 Tinkerer OFFLINE  

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Posted June 14, 2011 - 07:43 PM

Is there a chance that the cam gear and crankshaft gear are off one tooth? The only way to tell is to pull the case off and check. With it being .300" off I would lean towards the gears being off a tooth or two. Good luck and keep us posted as to what you find out.

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#4 MH81 OFFLINE  

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Posted June 14, 2011 - 10:55 PM

I had the same problem with an MF 8 that looked like it had a different engine in it. Asked the local mechanic, he told me that some Smaller Tecumseh engines were punched wrong on the cam and assembled that way. He said all the ones he had seen were 3 teeth off. I can't remember if it was retarded or advanced, but I think the cam was turned CCW vs the crank. If I am wrong, please let me know.

#5 1badMF OFFLINE  

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Posted June 14, 2011 - 10:59 PM

The ignition timing is set directly off the crankshaft. cam timing shouldn't be a factor. I did a visual on cam timing and the intake valve opens (guessing of course) about 3 degrees BTDC when I cycle the motor by hand. That should be normal.

Is there a difference in the position of the points on the electric start and recoil start magnetos because of the charging system windings?

A friend had an aftermarket parts manual that sold factory replacement points and mine didn't look like the picture. I was wondering if maybe the points are different also.
My wife is out of town with the camera so I can't post pics.

#6 1badMF OFFLINE  

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Posted June 16, 2011 - 12:10 AM

I think I may have figured it out!!!!!! Two different Stators. I bought one off of Ebay for 31.99 shipped. Gonna have to wait and see if that cures the problem. the pic on top of the box is the current one that is out of time. the one pictured with the regulator has the points in a different location, which looks to be where the lobe on the crank is @ .090" BTDC.
WOO HOO, I hope this cures it!!!! Massey will ride again. If not I will have two stators for sale.

Attached Thumbnails

  • stator 610938.jpg
  • stator 610818.JPG

Edited by 1badMF, June 16, 2011 - 12:15 AM.


#7 millwright OFFLINE  

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Posted June 16, 2011 - 06:34 PM

my mf8 uses the stator in the first picture from what i can tell. i just got done timing mine the worst part was taking 20 pieces of sheet metal off just to get to the head.

#8 1badMF OFFLINE  

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Posted June 16, 2011 - 10:22 PM

The cranks must be machined different.




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