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First Bike/Project: 1996 KTM 250 EXC?

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Hey guys I'm pretty new to the forum although I've visited frequently for research purposes.

I apologize in advance for the lengthy post but I'm sure it could be an entertaining read for some 2T members.

I have a nasty habit when it it comes to impulse buys of firearms and toys in general but needless to say I bought my first bike a couple months ago on cragislist. I grew up riding four wheelers and I've tinkered with a couple mopeds here on campus but I felt a need to get into the big boy stuff. So I picked up what I thought was a 1996 KTM 360. I knew the moment I bought it that I was probably in over my head but I've only ever made money off two wheel purchases to this point so I thought it couldn't hurt. Plus there was something about this thing that just oozed sexiness so I couldn't resist. Maybe it was the orange and purple combination. The story behind the bike was this guy only had it for about six months but it was too big for his son so he wanted to sell it. Supposedly all he did was install a new air filter.

This is her loaded up for the trip back:

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I didn't really have a checklist of things to look for when I bought it which is my fault but I knew it wasn't in great condition and probably needed some work. The front tire had some serious dry rot, the grips were disintegrating, the clutch and brake levers were broken off on the ends, and the plastic was in rough shape. The bike definitely took a couple tumbles by the look of it but that comes with the territory. It started up first kick every time so I was happy with it.

I took it home and rode it around a little and to my surprise I didn't hurt myself considering that was my first time on a two stroke bike. I started researching maintenance for this bike and it was then that I discovered this thing was basically a unicorn and impossible to find info and parts for online. Apparently this bike was only made in '96 and '97 so I started to get a little worried (yes I should have known this when I bought it) . I took her on some trails behind a house I used to live at off campus and everything went pretty well.

 

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I started it up and took it for a little spin at least every other day to make sure everything was okay with it. I started working on some cosmetic stuff here and there. I took the front wheel off and bought a new tire.  Fast forward a couple weeks and I was taking for a spin around the block when it died out on me in second gear. I wasn't able to get it started again that night but the following morning it kicked over and revved for about a minute but died again when I went to put it in gear. I had a feeling it wouldn't be long before I started having problems with it. I figured I should begin troubleshooting with the carb because every time I tried to start the bike it seemed flooded. After some research I took the bottom bowl off and unscrewed the jets. It didn't appear to be extremely dirty or anything but there was some tarnish in the bowl and around the jets. I attempted to clean them but I'm not sure how much good I did because I only had some seafoam to use at the time. I put everything back together and tried to start it again with no luck. I tried bump starting it down my driveway a few times and on my last attempt it fired and ran for about fifteen yards but died out again.

 

At this point, frustrated, I took the bike over to the suzuki guys because the local KTM dealer wouldn't touch it. After sitting there for three weeks, they told me that it was a compression issue after looking through the exhaust port. He wanted about $800 to resleeve the cylinder and drop a new piston. At this point, I had plenty of time to do some more research so considering he hadn't even started breaking it down yet, I went ahead and picked it back up to put in a new piston by myself. So I ordered a new piston for a KTM 360 and began the process of tearing it down. It took forever because every step of the way I had to clean off layers of caked on dirt and grime because apparently no one had cleaned the engine area of the bike before. I discovered the "coolant" was basically rusty pond water. The power valve and covers were pitch black and oozed thick carbon sludge. Upon removing the cylinder I didn't see anything too alarming. The only thing I noticed was some wear on the very top edge. I compared that spot to the piston to see if it was causing any damage but I couldn't really see any correlations.

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So I went to put in the new piston and realized it was bigger than the original one. I should have looked at it before ordering a new one. Apparently I bought a 1996 KTM 250 EXC instead of a 360. The piston I needed was a 67.5mm instead of the 72mm or whatever that I ordered. I'm sure it would be obvious to most people but I really had no idea and I had never ridden anything else of that size to compare. I don't think the previous owner tried to sell it as a 360 on purpose. I was pissed for a while until I realized the 250 is a much more common bike and parts are about half the price.

I am currently waiting for the right piston to get here but in the meantime I'd appreciate some opinions on the piston/cylinder or advice in general on this dinosaur. I feel like I owe it to the bike to get her back running again.

Go Tigers

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I wasn't happy. More pissed just because it took me so long to realize it. No markings what so ever and KTMs were so confusing back then.

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I noticed on the side of the cylinder base there is a stamp that reads "STROKE 69.5" but I didn't even pay attention to that until I saw 69.5 on the old piston.

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Definitely a 250 then - probably best to throw a new sleeve and piston kit in it

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What do you recommend as far as a new sleeve and piston? The suzuki guy wanted to ship the cylinder off and have it replated I believe for $200-$300. I'd need a matching piston I assume. LA sleeve doesn't have any kits for that year. Would I be able to get away with my cylinder as it is? I know its probably hard to tell by those pictures. It doesn't look to be in that bad of shape compared to some that I've seen on eBay.

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No I didn't. I don't really have all the tools. But he told me a new piston, rings, and gaskets should get it running for a while at least so I might just do that and replate if it goes bad again.

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those bikes are still great. and if you want to update the cosmetics i fitted 2013 tank/plastics/ subframe to one. it was quite easy. IMO they can handle better than the early pds suspended bikes too. 

most of the engine bits fit from later engines (i think up to around 2005ish)  for example so can convert it to the later adjustable powervalve . clutch, gearbox, piston etc all the same.

the worst thing is the ignition on those models as they can fail suddenly.

id personally replate the original cylinder as its cheaper that way.

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Awesome thanks for the tips.

My next concern on this thing is the front forks. They seem to be leaking a little. Mainly when I took it on those trails that one day I noticed some oil gathering on the bottom of the forks. Has anyone just done a fork swap on these? I think they are the 48mm but I can't remember the brand. I think I remember reading that the 50mm that came on the bigger bikes of this year are still pretty desirable. I'd like to at least upgrade to fork guards instead of the old boots. I kinda like the retro look at the same time but who knows.

I agree the replating is probably the way Togo because some people complain about the heat retention and everything with the sleeves.

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If you are going to spend big bucks, sure you can make almost any modern front end fit but getting the original ones rebuilt to suit your weight etc would be a better bet

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it sounds like you blew the head gasket/oring. super easy fix. -The bike will sometimes run intermediately depending the on temperature but then quickly stall and youll kick it until you pass out with no luck.

Are your radiators banged up? this would cause this if they are bad enough.

 

A cylinder replating is $200-300. I just do that instead of resleeving it.

 

For a shop to replace the fork seals is ~$100 from what I remember. Though your suspension is probably totally sacked out for bike that is over 20yrs old. 

for a suspension rebuild from a dedicated suspension shop is ~ $600 +/- $200. 

Might be better off finding better condition forks on ebay.

 

You could freshen up the plastics with that dirtbike plastic restore product, better then spending $200 on plastic on a bike that has other problems.

 

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I started the process of repairing the plastic when it died on me. I really only need a new rear fender and light which I found on ufo for like $40. But I've been told I can get away with new piston a rings for now. If I need to replate the cylinder in the future I can do that.

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The radiators look to be in good shape but they were full of basically sand water. I need to flush it when I get it back together.

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I got the old girl running a couple days ago. I dropped the new piston and put everything back together. I wanted to go ahead and clean out the carb properly while I was at it but I was impatient so I tried starting it up that night with no luck. I knew the piston helped because there was significantly more compression than before but it seemed like it wasn't getting fuel. I stayed up and took the bowl and jets out of the carb and let them soak overnight in carb cleaner. The next day I noticed that I couldn't really see through the hole in the main jet so I cleaned it out a little more and put everything back together again. Sure enough it turned over within a few kicks. I flushed the coolant until it ran clear and put in fresh Engine Ice.

 

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I ordered a new rear fender for about $30 but had to do some trimming around the middle centering holes for it to fit properly. I noticed that the previous fender had similar cutouts so I'm not exactly sure whats going on there but the new one made a huge difference cosmetically. It even makes the side panels look dingy so I'll probably replace those somewhere down the line.

 

My concern right now is trying to reseal or connect the pipe back to the silencer. I noticed some sort of disintegrating rubber gasket laying on the silencer pipe with a hose clamp on the pipe side. I'm not sure how it's supposed to be set up but currently its spraying carbon goo on my kickstarter and engine cases. I tried burning the carbon build up out of my pipe with a heat gun but I don't think it worked very well. Does anyone know an easy fix for the silencer/pipe connection? I've seen some metal connector pieces online but I'm not sure how that would work. 

I wrapped the split rubber gasket thing around where the silencer joins but its not doing any good.

 

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Its hard to tell by the picture but that's what I'm dealing with.

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Part number youre after for the pipe is  54605157000

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Are you missing the tension spring as well ? part number  51005063000

 

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Edited by S.O.A.N.Z
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Thats the piece I need to replace. Is it supposed to go around the joint area and be clamped down somehow? It was virtually impossible for me to try to hose clamp it in that spot with the frame and suspension right there.

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Wait I definitely don't have a tension spring. That would explain the matching loops. Thanks for the diagram. So I slip the gasket on the pipe end, attach the silencer and spring, and seal it up with silicone?

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