mac chainsaw

Reply

  #1  
Old 04-18-05, 03:39 PM
justshootme
Visiting Guest
Posts: n/a
mac chainsaw

For the love of god someone help me with this. Mac Eager Beaver starts and runs at idle, wont run at full throttle to save my life. Rebuilt carb, replaced plug, checked muffler, checked key way (worn but did not show to have slipped). Spits fuel out of carb and exhaust when throttle is depressed and is hard to crank wants to kick back. New fuel and all seems to be in order. Almost seems to be out of time.
 
Sponsored Links
  #2  
Old 04-18-05, 03:46 PM
puey61's Avatar
Member
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
Sounds like you need to remove the muffler as well as the spark plug and inspect the piston and cylinder for scoring. My guess is that you'll find damage to such.
 
  #3  
Old 04-18-05, 04:22 PM
justshootme
Visiting Guest
Posts: n/a
mac

pulled plug and exhaust. mind you i am no expert but did not see any major trauma. cylinder and piston look to be in decent shape actually
 
  #4  
Old 04-18-05, 11:08 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,814
I agree that it sounds like the cylinder/piston are shot. Maybe not though. No scratches or scrapes in the cylinder? It may need a new ring. The reason the cylinder and piston are suspect is because you say it blows back through the carb. About the only way a 2 stroke can do this is when air gets past the piston. Unless maybe the carb is flooding badly, but then you'd have a better chance of it running wide open but not at idle instead of the reverse.
 
  #5  
Old 04-19-05, 06:01 AM
justshootme
Visiting Guest
Posts: n/a
mac

Decided to try and spin rings around to see if broken. Spun top ring with no problem. Which got me thinking should i be able to do this with ease? Piston rotates with ease in hole about 1/8 turn. Is this normal?
 
  #6  
Old 04-19-05, 07:52 AM
Beaver lout
Visiting Guest
Posts: n/a
Compression

When you crank it over can you feel much compression? So long as there is good compression a two stroke engine should basically run. I assume you have tried varying the mixture whilst it's running and tried opening the throttle whilst you do so? Two stokes, particularly of this size, are very fussy on mixture and the condition of the exhaust silencer or muffler or whatever you want to call it. They won't run with no muffler but they also won't run with a sooty one, even if it's not very blocked. So long as you can feel a reasonable amount of compression and it cranks over reasonably smoothly, it can only be a problem with the mixture or the exhaust.
Hope this helps.
 
  #7  
Old 04-19-05, 11:18 AM
puey61's Avatar
Member
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
It's been some time that i've gotten deep into this model saw, but...You may have a blockage in the muffler. I don't recall if there is a spark arrestor screen or not so take a look. This may well be the problem or if there is not one, check the inlet and outlet ports of the muffler for any carbon build-up. Any such will create excessive backpressure and cause the exact trouble you have.
 
  #8  
Old 04-19-05, 09:07 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,814
The piston rotates 1/8 turn in the cylinder??? As in, it spins perpendicular to the stroke? If so, it sounds like the bearings came out of the rod.
 
  #9  
Old 04-20-05, 04:02 AM
justshootme
Visiting Guest
Posts: n/a
mac

No bad rod sounding noises when running but the piston dang sure is free enough. The slack seems to be in the wrist pin. Plenty of compression damn thing will pull your arm off if you dont have a good grip. Muffler may be an issue i have checked the screen and it looked OK but did not check the ports. Will do next.
 
  #10  
Old 04-21-05, 06:18 AM
justshootme
Visiting Guest
Posts: n/a
S.o.l.

Muffler did not seemed to be stopped up. I am gonna put it back together one more time before i throw it in the ditch unless someone has a better idea. Thanks for all the help guys sorry i cant do much for you. I am a surface prep (sandblasting/vibe) expert if i can help with that let me know.

Late
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes