Kids Quads Discussions about Kid's Quads and other ATV's.

LT-A50/KFX50 top end replacement difficulty?

  #1  
Old 10-26-2018, 02:33 PM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default LT-A50/KFX50 top end replacement difficulty?

So I picked up a 2006 KFX50, did the typical restrictor removal (exhaust, piggy back, intake, 67.5 main, air box). Still been somewhat difficult to start, and very little bottom end power, still sputters on the top end. But as I started it today, I could see smoke come out of the head gasket, and also some almost foam. I assume my head gasket is toast. I can have the head shaved down .045, I donít really fear taking the head off, but if Iím going that far, should I go all the way and pull the cylinder off? Iíve got to say, the piston didnít look the greatest when I had the flashlight in there doing the exhaust.

Is this essentially a beginner job? Do I need to pull the whole engine? I believe I understand the basics, but the last time o touched a piston was small engines class in 98 and I was probably high.
thanks for the advice
 
  #2  
Old 10-27-2018, 09:13 AM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default

Pulled the head this morning, cycled the cylinder, it seemed pretty smooth. Bit of carbon on the combustion chamber. Not sure anything stood out as excessive.
 
  #3  
Old 10-27-2018, 12:26 PM
Extreme Pro Rider
LT80 Expert
Join Date: Mar 2001
Posts: 7,927
Likes: 0
Received 0 Likes on 0 Posts
Default

1) please don't shave the head that much. I bet it'd hit the piston. I'd leave it stock for now.
2) get it together and do a compression test.
2 strokes top ends are easy. We'll help.
 
  #4  
Old 10-28-2018, 03:44 AM
Extreme Pro Rider
Join Date: Oct 2013
Location: Lancaster England
Posts: 3,805
Likes: 0
Received 0 Likes on 0 Posts
Default

To check if the head is warped, and also flatten it if it isn't too bad, I get an old sheet of glass, rub some coarse grinding pate on it and slide the head about on that. Where the paste is taking metal off, the surface takes on a dull grey/white appearance, if this shows a low spot, continue until it disappears. You will get fed up of doing this before you take too much metal off. You can do the same with the cylinder top surface if you think it is warped. Clean all traces of grinding paste off with solvent before re-assembly. If you do take the cylinder off, I would get it and the rings checked for wear. The rings may have a right way and wrong way up, and there will be a peg in each ring groove that the ring gap has to sit against, as two stroke rings must not move round on the piston.
 
  #5  
Old 10-28-2018, 08:35 AM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default

I can say, itís incredible that this forum goes back to the years before during and after the LTA50. Lots of information stored in there.

i got the .045 number from those archived posts. Iím under the belief at the moment that the head may have a slight warp. I could see the exhaust when cold, seemed to get better when warm. Iím going to take the head to a very experienced shop. I can probe and see what they think.
www.billbune.com

the goal is to have it back together and relatively functional in 2 weeks for the kids birthday, after that I can go deeper if needed. I have to draw the line somewhere I guess. I want the quad to have enough power to move on a limited throttle, and run good enough for the wife or grandma to start.




 
  #6  
Old 10-28-2018, 08:49 AM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default

https://youtu.be/MnQqOm3dz6M

As it got hot, it ran worse too. The wife wasnít able to drive it back to the garage under itís own power. I go 275 so it will be a bit different with the 35lb kid on it
 
  #7  
Old 10-29-2018, 08:26 AM
Extreme Pro Rider
LT80 Expert
Join Date: Mar 2001
Posts: 7,927
Likes: 0
Received 0 Likes on 0 Posts
Default

I wonder if the pipe is plugged.
 
  #8  
Old 10-29-2018, 08:33 AM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by LT80 View Post
I wonder if the pipe is plugged.
I can certainly put a little more effort into checking it. Looking down the pipe when I was checking for that exhaust restrictor looked clear. Exhaust does flow out the muffler, but it certainly could be a little restricted. There was a lot of carbon built up on the combustion chamber.

When I bought the quad and brought it home to go through it good, the spark plug wasn't even tight. just black from soot. cant believe it started and ran.
 
  #9  
Old 10-29-2018, 08:51 AM
Extreme Pro Rider
LT80 Expert
Join Date: Mar 2001
Posts: 7,927
Likes: 0
Received 0 Likes on 0 Posts
Default

Take the pipe off and throw it in a fire (fire/charcoal/wood stove/etc) and get it red hot. Blow compressed air threw it. CAREFUL it'll blow flames.
 
  #10  
Old 10-29-2018, 09:23 AM
Weekend Warrior
Thread Starter
Join Date: Oct 2018
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by LT80 View Post
Take the pipe off and throw it in a fire (fire/charcoal/wood stove/etc) and get it red hot. Blow compressed air threw it. CAREFUL it'll blow flames.


Ok, I was going to say, I think I do have a plumbing snake that might work
 

Thread Tools
Search this Thread
Quick Reply: LT-A50/KFX50 top end replacement difficulty?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: