GasGas Riders Club Forum  

Go Back   GasGas Riders Club Forum > GasGas Enduro Technical Forums > Enduro Engine - 2 stroke

Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


Reply
 
Thread Tools Display Modes
  #1  
Old 03-31-2016, 09:03 PM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default Complete Rebuild - EC250

I haven't seen a complete rebuild or walk through on the forum. Maybe I didn't search hard enough. Maybe this will be over-simplified, but I thought it might help someone who needed some motivation or confidence booster.

This EC250 belongs to a friend and fellow forum member. He was riding it a few weeks ago when the engine seized up. While washing it down, he noticed that the carb-to-air boot was disconnected. Here it goes:

Tonight, I'll start with the top end:

I started by removing the water pump cover:


The water pump impeller was seized to the bolt:


Gently pried out the shaft seal:


Remove the clutch cover:


Remove the right side power valve cover:


Removed the kick start lever:


Removed the shifter:


Remove the 6 bolts that hold the right side cover on. Gently pull that cover off:


Removed the lower nut that retains the power valve lever arm:


Removed the upper nut that retains the power valve lever arm:



Last edited by RockefellerGG; 07-13-2017 at 04:11 PM.
Reply With Quote


  #2  
Old 03-31-2016, 09:03 PM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default

Gently slide the lever arm off the posts and down through the hole:


Remove the two bolts for the thermostat cover and the 6 cylinder head bolts:


A view of the head underside. Notice the gouge marks:


A view down the cylinder. Notice the damage to the top of the piston:


Remove the left side exhaust valve cover:


There are 4 nuts that connect the cylinder. 2 are located under the side covers:


A gentle tap with a deadblow hammer helped pop the cylinder off the engine. If you're not doing the bottom end, be sure to stuff a rag under the piston to avoid dropping anything into the bottom end.

Remove the circlip from one side of the piston and gently press the pin out from the opposite side:


The piston walls look pretty good. No real signs of blow-by or low compression.


This piston top took a beating:


Reply With Quote
  #3  
Old 03-31-2016, 09:04 PM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default

Notice the big piece of brass that was sitting under the piston:




A couple good gouges in the cylinder wall, right above the power valve:
Reply With Quote
  #4  
Old 03-31-2016, 09:25 PM
GGRider01 GGRider01 is offline
Senior Member
 
Join Date: Jun 2015
Posts: 483
Default

So... what's the verdict here? Foreign matter in the combustion chamber... who knows what's in the crankcase. I hope you document everything if you decide to do the bottom end - love these kind of threads.
Reply With Quote
  #5  
Old 03-31-2016, 09:34 PM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default

Looks like foreign matter in the combustion chamber based on the gouges in the head and piston. I assume it locked up the piston and destroyed the connecting rod bearing. I don't know what the brass/copper piece is, but I'm sure I'll find out. Lots of slop in the connecting rod:

Not sure if photobucket videos work here, but here it goes:


With the amount of debris down in the bottom, I'll be splitting cases and documenting. Just not tonight.
Reply With Quote
  #6  
Old 03-31-2016, 10:08 PM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default

Upon closer inspection, you can see a brass or copper spacer on the left side of the connecting rod. I assume there was one on the right side as well. This is the big piece of debris.

Not sure if a piece worked it's way up into the combustion chamber or if it started from the top down.

Chicken or egg?
Reply With Quote
  #7  
Old 03-31-2016, 10:23 PM
Jakobi's Avatar
Jakobi Jakobi is offline
Super Moderator
 
Join Date: Oct 2010
Location: Australia
Posts: 7,858
Default

Quote:
Originally Posted by RockefellerGG View Post
Looks like foreign matter in the combustion chamber based on the gouges in the head and piston. I assume it locked up the piston and destroyed the connecting rod bearing. I don't know what the brass/copper piece is, but I'm sure I'll find out. Lots of slop in the connecting rod:

With the amount of debris down in the bottom, I'll be splitting cases and documenting. Just not tonight.
It looks like one of the thrust washers off the bottom end of the rod.

and from reading further I can see you've found that too
Reply With Quote
  #8  
Old 03-31-2016, 11:00 PM
barossi73's Avatar
barossi73 barossi73 is offline
Gold Level Site Supporter
 
Join Date: Jan 2014
Posts: 546
Default

Id say both the chicken and egg are overcooked m8!
__________________
2013 ec200r
Reply With Quote
  #9  
Old 04-01-2016, 12:38 AM
Rick's Avatar
Rick Rick is offline
Senior Member
 
Join Date: Aug 2006
Location: Lodi, Ca
Posts: 1,932
Default

My guess is the crank bearing / thrust washer let go.....chicken.....

please keep this thread going!!!
__________________
Rick
99 EC 200
06 RM 250
AMA D36
375X
OTHG
375S

***Thanks for the support : Twin Air /O'Neil Racing / Race 100% / Matrix Concepts / ODI / Mika Metals
Reply With Quote
  #10  
Old 04-01-2016, 10:32 AM
RockefellerGG RockefellerGG is offline
Senior Member
 
Join Date: Mar 2015
Location: Raleigh, NC
Posts: 238
Default

Here we go! Time to split the cases:


Clutch Disassembly

Start by removing the clutch spring bolts, the springs and spacer:


Slide out the clutch press plate, the friction discs and steels:


Drive down the safety washer using a hammer and screwdriver or punch:


Remove the clutch hub nut. This is pretty easy with an impact wrench, but you'll need to hold the clutch hub. It can be done with a standard ratchet set, but will take some patience.


Remove the clutch hub. The washer may stick to the back. Keep an eye out for it:


Lift off the clutch housing:


Remove the clutch bearings:


Remove the bushing:


And Washer:
Reply With Quote
Reply



Thread Tools
Display Modes

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Complete 2002 ec300 rebuild/conversion astout93v General Discussions & Announcements 1 12-07-2014 12:58 PM
S3 Race Custom Modified EC250 Complete Rebuild Jakobi Enduro Engine - 2 stroke 173 06-23-2014 03:12 AM
2011 ec250 engine complete 70hrs roverhybrids Parts 3 01-16-2014 08:20 PM




All times are GMT -5. The time now is 03:50 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2009 - GasGasRider.org