CR125 Top End Rebuild, NEED HELP!

laramik said:

The cylinder is in great shape, no gouges whatsoever and maybe the tinyest of chips near an exhaust port.

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This concerns me. Anything less than perfect, especially on a plated cylinder, is likely to get a lot worse real quick. If that chip is where the ring will side over it I would expect it to continue chipping.

laramik said:

The old piston also had a ring on the top which i guess indicated possibly a bad wrist pin bearing. The one in there certainly does not hold the wrist pin tightly by any means.

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I don't understand what you are saying here. The wrist pin is NOT held tightly. It is a precision fit into the piston, which is why you get a new one with every new piston. The pin should slide into the piston fairly easily. The wrist pin has to roll in the bearing easily. The bearing should be easily inserted into the rod end.

Did you replace the wrist pin bearing when you replaced the piston? I usually replace the bearing just because and if there was anything suspect about it at all then you should have changed it.

laramik said:

Im missing a couple different crankcase bolts, 1 by the kickstarter mechanism which Im guessing is why my kickstarter return spring isn't working, and another by the water pump.

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I am not familiar with your bike but I doubt that the kickstart return has anything to do with the bolts holding the cover on. The kickstart return spring is inside the cover. The right side "crankcase cover" is a casting that will have the water pump on it, the kickstart shaft coming out of it, held on with a half dozen or so small bolts.

If the return spring is broken you will need to remove the side cover to replace it. I would not expect this to be a difficult job, but you do want to pay attention to the governor and make sure that none of the pieces go bouncing out and get lost. It also helps to have manual so you can see how to put it back together.

If the missing bolts are simply missing then they are easily replaced. If they are missing because the threads are stripped then you should really fix them with a "heli-coil"

laramik said:

I filled her up with oil last night on the cranckcase cuz it was bone dry, what seems to be the drainplug on the bottom has nothing that I could use to get it off?? Is the drain the screw on the right side of the case not the magneto side? there is what appears to be a screw with a brass washer that might be a drainhole?

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I would expect the drain plug to be a fairly good size bolt on the bottom of the case. It is big to allow the oil to drain out, not because it needs to that tight. It could have a small head, like for a 12mm wrench but it wouldn't surprise me if it required something like a 17mm wrench.

These bolts are in harms way and it is not unusual for them to get banged on rocks and damaged to the point that a wrench won't go back on. You can sometimes get them off with a pair of vice-grips but I have had to take a chisel to one to get it off. Before you chisel it off, order up a new one, it should cost you about $5.

laramik said:

Any idea how much oil and what kind goes in there.

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The oil volume might be marked on the side of the case. Mine says 750ml. Unless you have gone to some lengths to get all the old oil out (like tipping the bike all sorts of different directions) there will probably still be some old oil left in there.

On either the case cover or the clutch cover there should be one bolt that is a little different than all the others. This bolt screws into the cover, rather than threw it and into the case. This will be the oil fill level. Remove that screw and fill the oil until it comes out that hole. I am guessing your fill level screw is just below and to the right of the A in HONDA on the clutch cover.

laramik said:

I mixed up some pre mix at 32-1 and lubed up the cylinder with 2 stroke oil before installing the piston. I am getting spark but it won't start. The petcock was all gummed up so I'm guessing that its the same inside the carb so I'll clean it tonight.

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Yes, the carb is probably a mess. You will need to take it, remove all the jets and clean everything. You may need to get a can of carburetor cleaner (and I don't mean the spray stuff) to soak the parts in over night. Just be sure that you don't soak anything made of plastic or rubber.

laramik said:

my Front forks are leaking a very little but everything else appears relatively ok.

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Fork seals aren't expensive and changing them really isn't that difficult. It took me a day and a half to fix the first fork and less than an hour to do the second one. A manual is essential, however.

laramik said:

Any advice on things I may be missing and what to look out for would be appreciated. I am desperately trying to get this running by this weekend so I can sell it and pay my rent. So please help.

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I encourage you to fix things right, especially with regards to the internal engine parts. I would hate to be the new owner of a bike that wasn't repaired properly.

Rod

and buy a service manual.

If you have to prime the cylinder or bump start it the compression is most likely too low. You'll probably lose money trying to get that bike good enough to sell........

Add to the list: You have coolant in your transmission. Not good. Vintage Bob

Water + oil + vigorous mixing (ie, gears) = what looks like chocolate milk.

I suspect that there was a reason that this bike was only $250.

In a two stroke there are very limited number of places where oil and water get close to each other. The most likely culprit is the seal on the water pump, or perhaps the water pump bearings are bad as well.

I suspect that the leaking oil is because you are missing several bolts that hold the case cover on. It is possible that a previous owner broke/stripped the bolts trying to tighten the cover down to stop the oil leak. You will need to remove the cover, extract any broken bolts, heli-coil any stripped threads and re-assemble with a new gasket. That cover needs to come off to replace your kick start return spring anyway. When you have the cover off inspect the mating surfaces and make sure there isn't a gouge where someone used a screwdriver to pry the case cover off.

As for the need to "bump start". No kick start return spring and really hard to start, hmmm, not a bike I would want to ride farther than I was willing to walk. You could have weak spark, poor carburetor jetting, air leaks, bad reed valves, low compression, or a partially fouled spark plug. I would start with a new plug as that is the easiest and it will also allow you to get a reading on the carburetor jetting.

Clutch Issue: Idles OK in neutral, won't idle in gear with clutch in, difficult to push with engine off and in gear with clutch pulled. Sounds fairly normal to me. This is referred to as "clutch drag" and to some degree all dirt bikes do this. There are issues with the clutch that can make it a LOT worse but it is possible that your bike is in the "normal" range.

Rod

I agree with Joe...run like hell from this bike. Get what you can get and call it a learning experience. I was $1100+ into my 1982 RM 125 "restoration" project before I threw in the towel. I sold it for $650.

Never have any intent of making money or even breaking even on a toy and you will live happily ever after.

Patman said:

Never have any intent of making money or even breaking even on a toy and you will live happily ever after.

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:cool:

laramik said:

I'm gonna throw on a new ring and try like hell to dump it for like 750. Here's hoping!!

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I really wish you wouldn't do that. Nothing pisses me off more than someone who bandaids a pile of junk and sells it to an unsuspecting victim.

If fixing the bike properly is not what you want to do then I recommend that you part the bike out and sell the pieces. Heck, you can probably make a decent profit on the deal.

If the wheels are in good shape I would expect that you would be able to get $60 to $80 each, maybe even more.

Each radiator could get $20 to $40.

The triple clamps should get $20, the plastics (if in good shape) could fetch some dollars. If the gas tank doesn't have any leaks it could get $40 or so.

Bottom line is that it wouldn't be hard to get your investment back, and possibly even make a few bucks. If you try to replace the ring and sell it quick it could be just throwing good money after bad.

What makes you think that the bike is going to start easily once you replace the ring? I am guessing that the previous demise of the engine was from the ring gap gouging the cylinder, causing the "chip" in the cylinder which in turn destroyed the ring. Your recent attempt to put a new piston in it just resulted in the ring catching on the chip right away, destroying that ring. The new ring will have its gap in the exact same spot, so it will catch just like the last two did and you will have the same result. Insanity is doing the same thing over and over and expecting a different result.

You are going to have a real hard time selling the bike with it leaking fluids and having to be bump started. I sure wouldn't pay you $750 for such a bike. Attempting to hide the oil and water leaks would be just plain dishonest and that can come back to haunt you.


Either sell it "as is" with full disclaimers or part it out.

Rod

I agree with Rod, sell "as -is" w/full disclaimer or part it out. That was a decent bike in it's day - the last year the CR125 (Honda) had a steel frame and the engine was not yet enemic. If it were me I would do a full blown restore but like mentioned before don't expect a return. If I wanted to make a few dollars I'd part it out but that can be a slow way to make money.