Go Back  RCU Forums > RC Airplanes > Questions and Answers
Reload this Page >

four stroke assembly

Notices
Questions and Answers If you have general RC questions or answers discuss it here.

four stroke assembly

Old 01-23-2007, 06:39 PM
  #1  
mteal
Member
Thread Starter
 
Join Date: Jan 2006
Location: welch, OK
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts
Default four stroke assembly

I was given a Magnum 80fs that is in a box in a bunch of peices. The guy said that it ran before he tore it down but he wanted to see how it worked. When he went to try to put it back together he couldn't get it to run. My question is this, how do I make sure that the valves are installed right with the right valve moving on the right stroke? This is my first four stroke and I dont know much about them. I have messed with two strokes for years but this is a whole different ballgame.

Thanks
Matt
Old 01-23-2007, 07:42 PM
  #2  
Campgems
Senior Member
 
Join Date: Feb 2006
Location: Arroyo Grande, CA
Posts: 4,465
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

Matt, does the 80 have the cam in front or in back?? If the cam is in front, you will find a small drill mark on the outside of the cam. With the piston at TDC, the mark on the cam points down. You can check with magnum service, they are great at answering questions. Other than the cam timing, the only other issue is adjusting the lifters. You want 0.002" tight, 0.003" loose and you have them set. Not much to it.

Don
Old 01-23-2007, 11:16 PM
  #3  
mteal
Member
Thread Starter
 
Join Date: Jan 2006
Location: welch, OK
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

The cam is in the front. I can take that info and run with it now. Thanks a lot Don!!!

Matt
Old 01-24-2007, 01:08 AM
  #4  
Campgems
Senior Member
 
Join Date: Feb 2006
Location: Arroyo Grande, CA
Posts: 4,465
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

Matt, don't know why I said what I did on the lifter adjustment. It should have been 0.002" loose, 0.003" slight drag.

Check with Golobal or Hobby People on the cam mark. I just went back over some of the old post and some are saying that it should straight down at TDC and others are saying it should be in line with the lifters. I timed mine with the lifters and it ran sort of OK, good high end but not so good at idle. I sent it into Magnum for service and they said the cam timing was wrong. When they were through, it ran good on high end but not so good at idle, in other words no change. It wouldn't hurt to get another opinion on the exact timing.

Don
Old 01-24-2007, 05:32 PM
  #5  
mteal
Member
Thread Starter
 
Join Date: Jan 2006
Location: welch, OK
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

I will check with them and then I will let you know what they say. Then we will both know in the future.

Thanks again
Matt
Old 01-29-2007, 03:22 PM
  #6  
mteal
Member
Thread Starter
 
Join Date: Jan 2006
Location: welch, OK
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

OK, The service department at Global said the the proper way to set the timing was..........

CRANK PIN AT 12 O'CLOCK (STRAIGHT UP) AND THE TIMING DOT ONE TOOTH AHEAD OF BOTTOM, ABOUT THE 5:30 POSITION.

This may help someone else a little later.

Matt
Old 01-29-2007, 05:05 PM
  #7  
Charlie P.
 
Charlie P.'s Avatar
 
Join Date: Feb 2003
Location: Port Crane, NY
Posts: 5,088
Likes: 0
Received 0 Likes on 0 Posts
Default RE: four stroke assembly

The guy said that it ran before he tore it down but he wanted to see how it worked.
LOL!

Not laughing at you, but the prior owner.

I once went to look at a 1940's Ford 8N tractor advertized in the classifieds as: "Runs GREAT!" When I arrived he started walking me around his garage and introducing me to the pieces scattered all over.

"How do you know it runs great?"

"It did when I took it apart. I can have it back together in a week."

"Here's my number. Call me when it runs great again and we'll talk."

Never did find out if he got her back together.

Did you check to see if there is a downloadable exploded diagram on their website?

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.