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My green lane bike

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My green lane bike Empty My green lane bike

Post  weasley Sun Apr 04 2010, 15:52

Some of you may remember that recently I bought an off-road bike for a bit of greenlaning. It's a 1996 Kawasaki KDX 125 and for the money it was a bargain. I bought with trepidation as I know how fickle 2-strokes can be but thought it would be an adventure nonetheless.

Well, the adventure has begun. Yesterday I was just popping out to the shops and as I pulled into the Tesco cap park the engine cut, the back wheel locked up and that was that. It still kicked over but no way was it going to start. I pushed it home (3 miles, done in two stints - included a 1-in-10 hill... up!) and today have started stripping it down. It didn't take long to see the problem - once the exhaust was off you could clearly see two huge gouges out of the bore opposite the exhaust port. That would be why there was no compression then!

Anyway, all was going well with the strip down until it came time to lift the barrel off of the piston. No way was it coming off and I have deduced that a ring has broken and become trapped in the inlet port of the barrel, thus preventing the piston from pulling out of the barrel. I have pulled, twisted and even given it a damned good swearing at, but nothing has worked.

Any advice or ideas from anyone? The engine is still in the frame and it's not like you can just drop the 'sump' off the bottom and release the big end from the crank (gearbox is in the way, see). I can't get enough access to the inlet port to try and free the obstruction from that way. I would prefer to try and save the con-rod, but the piston and barrel are junk so happy to trash them if needs be. I did think about trying to rig up some kind of press on the cylinder head studs, to screw down onto the piston and push it down but haven't yet worked out how to do that.
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Post  Rosco Sun Apr 04 2010, 17:22

Nice try.....not falling for that one again!
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Post  Guest Sun Apr 04 2010, 17:38

Who is going to believe you now after your April fools' prank ? pmsl
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Post  weasley Sun Apr 04 2010, 18:43

Well, as I was taking the cylinder head off, Kate Winslett popped in to try and persuade me to have an affair. Then I found a winning lottery ticket down the back of the sofa.

Come on guys, can't you take a joke?! This is serious now - grow up! tongue
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Post  Panzerbuilder Sun Apr 04 2010, 20:12

Three suggestions W.

1. Give the piston a good twatting form the top to try and move it to free the obstruction. naughty
2. Chain drill the top of the piston to free the conrod and extract both the CH & piston. Push cloth into the inlet and exhaust ports to catch the swarf.
3. Push it to the back of the shed and forget about it!tongue

And the 1st April post was brill. You had me going as well. You should have been on Jackanory! jocolor
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Post  JDM Sun Apr 04 2010, 20:46

Panzerbuilder wrote: 1. Give the piston a good twatting

Would that be the technical description?? Haha like it! my kind of mechanics
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Post  yamahamad Sun Apr 04 2010, 21:20

It sounds like the only way is going to be to remove the engine & strip the bottom end. You may end up replacing the barrell if the scores are too deep to bore out anyway. Not sure what that type of engine looks like if you take a couple of pictures we might think of a good idea. Paul.
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Post  weasley Sun Apr 04 2010, 22:17

I'll try and get some pics tomorrow. Will deffo need a new barrel - these grooves were deep enough to completely destroy any compression.

Twatting it seems to be the best solution so far! Unfortunately as the engine is still in the frame there's not a lot of twatting space - I'll get the tank off and see if that allows room for a decent twatting; I have a good twatting hammer.

I really don't want to have to strip the bottom end out... Neutral
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Post  Ezzy's Mum! Sun Apr 04 2010, 23:52

weasley wrote:

Twatting it seems to be the best solution so far! Unfortunately as the engine is still in the frame there's not a lot of twatting space - I'll get the tank off and see if that allows room for a decent twatting; I have a good twatting hammer.

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What is this 'twatting' that everyone keeps referring to these days ....... and where can i buy one of these 'twatting hammers' from please Smile
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Post  Krusty Tue Apr 13 2010, 07:18

You don't want to bend the conrod though. If you're writing off the barrel what about gaffer-taping up the bottom end and angle grinding the barrel off of the piston - two vertical slots on either side should only take 5-10 mins
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Post  weasley Tue Apr 13 2010, 11:57

Well unless the con-rod is at BDC then there shouldn't be any risk of damaging it or its bearings. I was planning on lifting the barrel a bit and chocking it underneath with some wood - the crankshaft will then be at some part-stroke angle, so it should simply move as the piston is driven out of the barrel.

Or something.
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Post  Krusty Tue Apr 13 2010, 21:04

Might be worth a tap with a drift, probably a bit of a lottery as to if and how the piston ring has jammed itself in between bore and piston and whether drifting the piston downwards will release it or jam it in harder.

I'm biased mind, I like angle grinders: ever since I used one to fix a 'broken' locking wheel nut Twisted Evil
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Post  Guest Wed Apr 14 2010, 20:25

If it's any consolation Paul (and I'm sure it won't be), I've gone and seized the engine on my Honda XL100.

I had been using it for commuting and had only done 200 miles or so. Stupidly, I hadn't checked the oil. Turns out it was losing a lot of oil somewhere (it wasn't obvious though). So the engine seized, I had to push it about 3 miles to get it to my parents where I have stripped it down.

I'm now waiting on my new piston, rings, gudgeon pin and circlips before getting a rebore. Luckily I can get this done through my workplace at very little cost. Hopefully I will be back on the road in a couple of weeks.

Hope your rebuilt is going ok.

Tony
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