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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: https://drive.google.com/open?id=0B8...mFpSzJjOVE.jpg The water pump impeller was seized to the bolt: https://drive.google.com/drive/folde...pshek3brgz.jpg Gently pried out the shaft seal: http://i71.photobucket.com/albums/i1...psb0omflcd.jpg Remove the clutch cover: http://i71.photobucket.com/albums/i1...psmrl2ptpm.jpg Remove the right side power valve cover: http://i71.photobucket.com/albums/i1...psu43zwx8b.jpg Removed the kick start lever: http://i71.photobucket.com/albums/i1...psvel7f3vd.jpg Removed the shifter: http://i71.photobucket.com/albums/i1...psaheulndz.jpg Remove the 6 bolts that hold the right side cover on. Gently pull that cover off: http://i71.photobucket.com/albums/i1...psgq8ewzso.jpg Removed the lower nut that retains the power valve lever arm: http://i71.photobucket.com/albums/i1...ps1q5cn44h.jpg Removed the upper nut that retains the power valve lever arm: http://i71.photobucket.com/albums/i1...psfhffy0uy.jpg |
Gently slide the lever arm off the posts and down through the hole:
http://i71.photobucket.com/albums/i1...psq6wlu49r.jpg Remove the two bolts for the thermostat cover and the 6 cylinder head bolts: http://i71.photobucket.com/albums/i1...psklimdefj.jpg A view of the head underside. Notice the gouge marks: http://i71.photobucket.com/albums/i1...psxfvzdseb.jpg A view down the cylinder. Notice the damage to the top of the piston: http://i71.photobucket.com/albums/i1...ps5dkahmbk.jpg Remove the left side exhaust valve cover: http://i71.photobucket.com/albums/i1...psuoxueckt.jpg There are 4 nuts that connect the cylinder. 2 are located under the side covers: http://i71.photobucket.com/albums/i1...psunhwryaw.jpg 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: http://i71.photobucket.com/albums/i1...psnmoeo0bg.jpg The piston walls look pretty good. No real signs of blow-by or low compression. http://i71.photobucket.com/albums/i1...pshm3mmxuf.jpg This piston top took a beating: http://i71.photobucket.com/albums/i1...psmkyii3wc.jpg http://i71.photobucket.com/albums/i1...ps60ax3gnq.jpg |
Notice the big piece of brass that was sitting under the piston:
http://i71.photobucket.com/albums/i1...psmkyii3wc.jpg http://i71.photobucket.com/albums/i1...psjr7cfaq1.jpg A couple good gouges in the cylinder wall, right above the power valve: http://i71.photobucket.com/albums/i1...ps6umugyff.jpg |
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.
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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: http://i71.photobucket.com/albums/i1...psodb5u2gf.mp4 With the amount of debris down in the bottom, I'll be splitting cases and documenting. Just not tonight. ;) |
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? http://i71.photobucket.com/albums/i1...pser12zviu.jpg |
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and from reading further I can see you've found that too :D |
Id say both the chicken and egg are overcooked m8!
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My guess is the crank bearing / thrust washer let go.....chicken.....
please keep this thread going!!! |
Here we go! Time to split the cases:
Clutch Disassembly Start by removing the clutch spring bolts, the springs and spacer: http://i71.photobucket.com/albums/i1...psjqvdb68p.jpg Slide out the clutch press plate, the friction discs and steels: http://i71.photobucket.com/albums/i1...pshx1yaups.jpg Drive down the safety washer using a hammer and screwdriver or punch: http://i71.photobucket.com/albums/i1...ps5yjm3nwo.jpg 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. http://i71.photobucket.com/albums/i1...ps1cb8lbot.jpg Remove the clutch hub. The washer may stick to the back. Keep an eye out for it: http://i71.photobucket.com/albums/i1...psdvjtp3cx.jpg Lift off the clutch housing: http://i71.photobucket.com/albums/i1...psjlyhht8l.jpg Remove the clutch bearings: http://i71.photobucket.com/albums/i1...ps3bn6cnnt.jpg Remove the bushing: http://i71.photobucket.com/albums/i1...psghxqaeqa.jpg And Washer: http://i71.photobucket.com/albums/i1...ps9iethfji.jpg |
Remove the two bolts holding on the shaft block and remove the assembly:
http://i71.photobucket.com/albums/i1...psb0iyv6pb.jpg http://i71.photobucket.com/albums/i1...psi4q1nfoo.jpg Lift out the centrifugal mechanism: http://i71.photobucket.com/albums/i1...psorlsfnnp.jpg Lift the kick start return spring out of the hole and release the tension: http://i71.photobucket.com/albums/i1...psggfc0pif.jpg Remove the starter pinion circlip: http://i71.photobucket.com/albums/i1...pscyfugcle.jpg Lift out the inner starter pinion and spacer washer: http://i71.photobucket.com/albums/i1...pswapu0xry.jpg Lift out the Starter pinion assembly: http://i71.photobucket.com/albums/i1...psgdzbbebr.jpg Remove the gear selector spring: http://i71.photobucket.com/albums/i1...psi46kegf5.jpg Lift the gear selector unit straight out of the case. Mine didn't come out too easily. It got tighter the further out i pulled it. There is a small white plastic bushing under it. Don't forget to grab it. http://i71.photobucket.com/albums/i1...psymr1ifqt.jpg Remove the spring from the hole and remove the bolt that holds in the gear lock: http://i71.photobucket.com/albums/i1...psbr5v9sfj.jpg |
http://i71.photobucket.com/albums/i1...psy6itvvtt.jpg
Time to remove the crankshaft flywheel nut. This is opposite thread. YOU NEED TO TURN THIS CLOCKWISE TO REMOVE IT. http://i71.photobucket.com/albums/i1...ps3aejd7tr.jpg Lift of the washer, crankshaft gear, and flywheel: http://i71.photobucket.com/albums/i1...psbkeie8re.jpg Don't forget the drive pin: http://i71.photobucket.com/albums/i1...pspx3iagnc.jpg Remove the reed block: http://i71.photobucket.com/albums/i1...pspd0oyvdj.jpg Remove the ignition cover: http://i71.photobucket.com/albums/i1...pswcd1ggst.jpg http://i71.photobucket.com/albums/i1...ps6pdbm2ik.jpg Remove the ignition flywheel nut: http://i71.photobucket.com/albums/i1...pspvwy0xa5.jpg Remove the flywheel using a flywheel puller: http://i71.photobucket.com/albums/i1...ps3vq6ahsj.jpg http://i71.photobucket.com/albums/i1...pssnv8ou3j.jpg |
I marked the timing position to help reassembly:
http://i71.photobucket.com/albums/i1...psmwhmk6fw.jpg Remove the ignition: It looks like there should have been three bolts holding it on, but this one only used two: http://i71.photobucket.com/albums/i1...ps07mamygp.jpg Remove the c-clip and front sprocket: http://i71.photobucket.com/albums/i1...psemun8xzl.jpg Fragments are everywhere! http://i71.photobucket.com/albums/i1...psr5vpwlqo.jpg Remove all the cap head bolts from this side. Notice that there are three lengths of bolts. Keep track of what goes where: http://i71.photobucket.com/albums/i1...psu6qamrtr.jpg I used my Tusk case splitter. I know this can be done with other techniques, but using the right tool for the job makes this a snap. It came right apart with no drama. It happened so easily, that I forgot to snap a pic of it all mounted up. http://i71.photobucket.com/albums/i1...pskt4i52e2.jpg http://i71.photobucket.com/albums/i1...psp45jxpeh.jpg All the sub assemblies are removed and put into labeled bags: http://i71.photobucket.com/albums/i1...pst090fr0o.jpg |
Awesome post! Thank you for taking the time and effort to document the tear down. I appreciate the detailed informative pictures.
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Nice post, thanks for sharing!
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+1
I stickied this thread so it will serve as a quick reference for those that need it. |
I just did a full rebuild. Where was this post then!?!?
Hahah!! Good work! Rad post! |
Glad you guys like it. More to come soon. Sending parts out and I hope to document the case mating and cylinder stacking in a couple weeks.
For now, I leave you with the removal of the inner bearing ring from the crank: Installed the bearing splitter and tightened the base under the ring: http://i71.photobucket.com/albums/i1...psdhyuchio.jpg Tighten down and the magic just happens: http://i71.photobucket.com/albums/i1...pslip7xd5x.jpg |
Removing the power valve internals from the cylinder
Ok, to send off the cylinder for repair, I needed to remove the power valve and bearings from the cylinder:
On the left-side, start by removing the bolt and washer that retain the two bearings: http://i71.photobucket.com/albums/i1...ps9ehoxjmq.jpg The bearings were frozen in there pretty good. I used a small torch to heat up the aluminum around the bearing and using a small L-shaped pick, they popped right out: http://i71.photobucket.com/albums/i1...psvugd1qup.jpg There should also be a small washer behind the two bearings, but it might be adhered to the exhaust valve. I pulled the pin and the exhaust valve came with it. Notice on this one, the washer is basically baked up against the little valve. They all separated with very little force. http://i71.photobucket.com/albums/i1...psrfpo1qkv.jpg I slid my long 4mm allen wrench through the hole of the shaft that was just removed and lined it up with the hole on the right side. With a little pressure, the right side valve assembly came right out: http://i71.photobucket.com/albums/i1...psk6bxsizf.jpg I inserted the 4mm wrench again into the small hole and drove out the other pin that acts as a hinge pin for the power valve. Push the pin out the right side and fish the power valve flap out of the cylinder: http://i71.photobucket.com/albums/i1...psskcvmmxn.jpg |
Amazing post. I'm just about to attempt my bottom end after something in there locked up shortly after burying it in a swamp. This is exactly what I've been looking for. Thanks !
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Just a quick question.. Did you use an impact for the flywheel nut, and was it threaded on normally, or opposite like the crank nut? (Since it is on the other end of the crank)
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Is using an impact generally frowned upon? I've been using that exclusively, along with the puller. Don't even need a backup wrench when popping the flywheel.
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I use an impact. Quick and easy.
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Sweet, thanks guys.
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I use an impact to remove nuts/bolts. Not for installing them. I cracked an expensive clutch basket a while back using an impact to install.
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Yeah. You can't be trigger happy.
Once the socket stops, let off the trigger. |
So, as stated earlier, I am in the process of replacing some crank bearings on my 2007 EC200 Hobby. I want to be a little pro-active and order the parts while waiting on a flywheel puller. Other than the bearings, seals and gaskets, what else should I order? Will it be necessary to replace the locking washer/tab for the clutch basket or can I be re-used?
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New top end?:) |
If you're doing crank bearings and seals, it may not hurt to replace the kickstart, shifter, and waterpump seal... and the primary seal/o-rings
I didn't think about this and decided to order them while I'm doing the crank seals. |
Transmission
Time to disassemble the transmission. When you split the cases, the gears may be in the opposite case side... mine came out this way, so here it goes:
http://i71.photobucket.com/albums/i1...psvmgqr6n7.jpg Slide out the shift rails: http://i71.photobucket.com/albums/i1...psbvgi9wnm.jpg http://i71.photobucket.com/albums/i1...pslzajrajn.jpg I marked the position of the shift drum, so I can make sure it goes back in the right orientation: http://i71.photobucket.com/albums/i1...pslgo8q74q.jpg Removed the shift drum: http://i71.photobucket.com/albums/i1...psubvedkqk.jpg Carefully remove the gear sets, keeping track of what went where: http://i71.photobucket.com/albums/i1...psyf7ayexo.jpg http://i71.photobucket.com/albums/i1...psm1av6yks.jpg http://i71.photobucket.com/albums/i1...psa8hwjpqn.jpg |
Crank Seal Removal
Remove the crank seals:
http://i71.photobucket.com/albums/i1...pskwnu6rqk.jpg On the other half, remove the spacer, and remove the seal: http://i71.photobucket.com/albums/i1...psffqvcfp9.jpg http://i71.photobucket.com/albums/i1...psjyxjvdfd.jpg |
Remove the seal for the primary shaft. There are 2 o-rings. One inside the spacer and one behind the spacer.
http://i71.photobucket.com/albums/i1...pslwygy292.jpg |
Removing the crank bearings
Time to clean it all up:
http://i71.photobucket.com/albums/i1...psuxagbqsq.jpg Removing the crank bearings: I started by removing all of the alignment dowels to let the case half sit flat. I used a large socket (1 1/16") to drive out the bearing: http://i71.photobucket.com/albums/i1...psudmnbefg.jpg http://i71.photobucket.com/albums/i1...ps7kagt3ci.jpg For the other side, I used a flat screwdriver inside the edge of the outer bearing race and drove it out. The bearing cage broke leaving just the outer race. I applied a little heat to help it release. http://i71.photobucket.com/albums/i1...psiblkicz7.jpg http://i71.photobucket.com/albums/i1...psqbflasah.jpg |
To help identify when it was last rebuilt, I etched in the date near the original factory etching. Maybe this will help some future owner... who knows.
http://i71.photobucket.com/albums/i1...psnn2aa2rf.jpg |
http://i71.photobucket.com/albums/i1...ps7kagt3ci.jpg
Bearing seat looks a bit rough. Rather than driving the bearings out, if you heat the cases the bearing will fall out on its own, or with very little persuasion. |
The pic looks worse than it is. Smooth to the fingernail.
I used heat on the other side, where there is nothing to hit, but it still took some persuasion. |
Since there are no raised edges, the new bearing should still drop right in. No ball or rotating surface will ever touch that surface... I'm not losing any sleep over it.
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Looks like your doing a nice rebuild, Jakobi makes a good point about heating the cases. Use an oven or a hot plate. The bearings will drop right out. Freeze the new bearings. When you put it back together, reheat the cases, and drop the frozen bearings right in, no tools required.
Ill be doing a full rebuild here in a couple weeks, i may use your pics instead of the manual, nice write up. |
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