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New to Kawi's and 2-strokes.

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Hey guys, I've been riding, racing and wrenching on bikes for years but recently bought my first 2-stroke and first ever bike that's not a Honda.

The bike I bought is a 2000 KX250, I've used the search and found some answers to questions I was having about the bike such as why does the thing rattle so much at idle (apparently normal on this bike).

The bike has been a little neglected, so I'm wondering what are some 2-stroke specific things I should address on this machine to make sure it's running at it's prime?

Does anyone have a .pdf service manual for this bike?

Any weak areas on this particular year KX I should address?

Thanks in advance fellas!

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It is a good bike with no real weakness. The lower shock bearing needs greasing and all the linkage should be greased too. That year IMHO has to tall of a first gear , the 99-01 all did and a 94-98 first gear fits and fixes it but most just ride them the way they are. I like the L series (99-02) bikes myself and have a 99 and a 01 and plan to keep them many more years.

BTW welcome the Kawasaki's and 2 strokes.

Ed

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Thanks for your reply, turns out it is a 2001 model as per the frame sticker.

I got bored tonight and decided to tear the bike down and have a look at things. For the most part it's fairly clean, but I found a broken reed:

kx001.jpg

kx002.jpg

How will this effect performance and how dramatically?

I also had a look into the cylinder, doesn't look great and looks like somebody did some porting. Opinions?

kx003.jpg

kx005.jpg

kx006.jpg

Another bad sign is that I reached into the ports and felt a fair bit of side play in the connecting rod, if I had to guess I would say that I could move it left to right 1 - 1.5mm.

So it looks like this engine is due for an overhaul. Do you guys typically re-plate these cylinders or should I look for a replacement? Are they chromed or nikisil?

If this was your bike, and you were in this position of requiring an overhaul, what parts would you use? (Piston, reeds, crank/rod combo, cylinder if required etc.)

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Some side to side play is normal. Up and down play is what you are really have to watch. If you can feel any up and down play then you definitely need to rebuild the bottom end.

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Spec on side to side clearance is .45 to .55 mm side clearance Maximum is .7 mm. I would measure it accurately before I condemn the bottom end.

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the motor isnt ported either. somone just went in there and cleaned up the intake a little. just trying to clean the casting. although i do the same to mine, yours looks a little rough. i wouldnt worry to much about it. the bore is nikisil plated. if it needs to be replated, send to millenium tech. you will be happy. they also supply the pistons and gaskets for an extra cost. get new reeds, bike wont run right with those reeds.

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Yeah Bansheedave, I thought it did look pretty haggard. Those two vertical skinny pieces are gnarled pretty badly, they look like they would break off with little effort.

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if they bother you, id have the repaired if you plan on replating the cylinder. otherwise your looking at a new cylinder. id hate to see them break after the cylinder gets hot if they are that skinny. just my 2 cents.

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Thanks for your reply, turns out it is a 2001 model as per the frame sticker.

I got bored tonight and decided to tear the bike down and have a look at things. For the most part it's fairly clean, but I found a broken reed:

kx001.jpg

kx002.jpg

How will this effect performance and how dramatically?

I also had a look into the cylinder, doesn't look great and looks like somebody did some porting. Opinions?

kx003.jpg

kx005.jpg

kx006.jpg

Another bad sign is that I reached into the ports and felt a fair bit of side play in the connecting rod, if I had to guess I would say that I could move it left to right 1 - 1.5mm.

So it looks like this engine is due for an overhaul. Do you guys typically re-plate these cylinders or should I look for a replacement? Are they chromed or nikisil?

If this was your bike, and you were in this position of requiring an overhaul, what parts would you use? (Piston, reeds, crank/rod combo, cylinder if required etc.)

Yeah don't get to worried about moving it side to side, even new ones do it, pull it up and down thats a different story !

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Well it's a good thing I pulled her down when I did... Discovered some cracks in the piston skirting.

kx009.jpg

kx010.jpg

kx011.jpg

Also noticed that the scoring on the piston although it's not very deep at all, is all on the intake side and may have been caused by that gnarly port grinding job if any of the port material was left over-hanging the port into the cylinder.

kx007.jpg

kx008.jpg

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At this stage, should I simply hone the cylinder and replace the piston or is cylinder plating necessary? There are no gouges in the cylinder wall that can catch a nail.

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With out seeing the cylinder it is hard to tell. I would be careful when honing the cylinder as you dont want to go through the nicasil plating. I have read posts about using steel wool on the end of a drill to clean the cylinder. I have always just hit real lightly with a bead hone. I am sure others will have there opinions on this. If it cleans up then you may get away with just a piston and ring. Looking at the scoring though, I would suspect you should really have it replated to do it properly. Good luck.

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Thanks Condor, I've read that with Nikasil plating you can only use the ball hones but I've never tried it before.

On my 450 I've never had any cylinder damage or scoring, so I've always just used soapy water and an SOS pad to clean any aluminum smearing off the cylinder wall.

Here are some pictures of the cylinder, you can see what I mean about the roughness at the edges of the ports:

kx012.jpg

kx014.jpg

kx015.jpg

kx016.jpg

kx017.jpg

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I've honed cylinders on automotive engines that I built, but they were stone hones, I know the basic principles to honing but of course those don't have ports.

I'll be sure to have the cylinder measured before ordering a piston.

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I have heard its not to hard, but you dont want too much crosshatch and it has to be angled properly, as you probably know.

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Hey guys, so I am ready to order a piston but I am just curious... Some brands (Pro-x) offer varying sizes for the piston, which makes sense to me as some bores are honed aggressively and re-plated as the cylinder wears.

But other brands (Wiseco) have no option for piston size, aside from stock bore original fitment.

Am I safe to lightly hone the cylinder and order the Wiseco piston with no option for sizing? Or should I have my cylinder measured, then order the corresponding size?

On my 450 I've always just ordered the stock bore 96mm pistons and set the ring end gap.

I don't have telescoping micrometers at my disposal, however I plan to purchase a set to measure my cylinders in the future.

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