1993 KX125 Build

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10/19/2020 8:06 AM

Just picked up this 1993 KX125 from my wife's brother. Plan is to restore it into a runner and give it to my wife's sister as a gift.

Seems to have a few good things going for it, already has the hard to find PC pipe and stinger silencer. PC worked on the suspension back in period (although looks to need a rebuild). Looks like a PC clutch perch. Seems to have relatively low hours overall.

Some concerns: My father in law seems to remember it was sleeved at some point in time, so may look into trying to find a new cylinder. Some oil on the stand, thinking shift shaft seal, countershaft seal, or separated oil coming out of carb (gas was left on when I got it, hasn't been touched in ~6 years)

Plan is new plastics, rebuild suspension, inspect/grease/replace all chassis bearings, rebuild calipers/master cylinders, rebuild carb, inspect cylinder.

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12/15/2020 6:36 AM

Finally started to tear into this, the contest that Cam and others are hosting was a good motivation to get it started.

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Teardown has gone pretty smoothly so far

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I have found that there was a major sealing issue between the pipe and the silencer which has blown carbon all over the back of the cases, carb, air boot, shock, linkage, swingarm etc. On my RMs, there is a rubber seal between pipe and silencer, didn't have one on this bike. Is it missing or did these not come with those seals?

Also, any tips to get the carbon cleaned off the cases? pretty much everything is going to go in the parts washer, but trying to avoid splitting cases if I can.

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Second problem, tab for the lower radiator mount on the left hand side of the bike has snapped off

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Third problem, bolts holding the Works Connection frame guards on were pretty rusted, were able to crack 3 out of 4 loose, was struggling with the 4th and just thinking about adding some heat and penetrating oil when she rounded off on me. First time I have ever done that, so need to get to the store and buy and extractor.

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Last thing, I have never seen a spark plug do this before.

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12/15/2020 10:33 AM

I'm in the process of rebuilding a 93 KX 125 as well, for the second time.

https://www.vitalmx.com/forums/Bike-Builds,46/1993-KX-125,1368642

Make sure you check your frame over. My frame had a few cracks in it, this is why I'm rebuilding it again. I've learned a lot rebuilding it, if you need any help let me know.

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12/15/2020 10:52 AM

jt.hagerty wrote:

I'm in the process of rebuilding a 93 KX 125 as well, for the second time.

https://www.vitalmx.com/forums/Bike-Builds,46/1993-KX-125,1368642

Make sure you check your frame over. My frame had a few cracks in it, this is why I'm rebuilding it again. I've learned a lot rebuilding it, if you need any help let me know.

Yeah I've gone through your build, looks great! Do you have any sort of rubber seal between expansion chamber and silencer? After I go through all the work to get this cleaned up, I don't want to blow carbon all over everything again

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12/15/2020 1:17 PM

ArizonaKevin wrote:

Yeah I've gone through your build, looks great! Do you have any sort of rubber seal between expansion chamber and silencer? After I go through all the work to get this cleaned up, I don't want to blow carbon all over everything again

I didn't when I first built it, it was tuned pretty good and didn't have oil blow everywhere. I just ordered a rubber connector for a late model KTM 125, I've used these on other builds and they work great.

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12/16/2020 12:04 AM

Heater hose and 2 zipties work.

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04 KX125
94 KX250SM
75 Z1-900