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Ill research on that bronze bushing idea. Sounds interesting. And Tyl3r, I have 2 bearings. One came with the ProX piston and one came with the rod kit. They are both the same size i'm guessing because the results are the same. If i was to go down the road of the bushing bearing idea, can you guys find a good explanation on how to do it? Sounds like a better outcome.

Typical running clearance between the wrist pin and the rod bushing is .0005" - .001". You'd want the bushing OD to be maybe .001" larger than the rod bore to get the needed press fit.

My Maico rods have their phosphor bronze bushings staked at either end to prevent movement.

To properly deal with this problem, you need to get the numbers. You need to know:

1) The OD of the wrist pin.
2) The ID of the rod bore.
3) The diameter of the needle rollers.

So, take the OD of the pin, add the diameter of 2 needle rollers, and subtract this sum from the ID of the bearing bore.

If the parts are right, you should end up with a slight clearance, maybe .001".

To find someone to take the measurements, ask around at auto parts stores or independent repair shops, lawnmower shops, places like that. You'd be surprised how many professional or retired machinists, or other guys into mechanical hobbies, have machine shops in their garages and basements.

IMO, the suggestion to mix and match old and new parts until you find a combination that fits is a good one. Another idea is to measure old and new parts and see which are the same and which are different. IMO, the problem is either an undersize rod bore, or oversize needle rollers. If the new piston is for your KDX, I can't imagine it would have a non-standard wrist pin OD.

Alright once I get those numbers ill post them. Ima look around today

" And also I will check if the old bearing will fit woth the new rod. I dont think it does if I recall correctly."

Then I will assume the new rod has an undersized small end ID.

Did you contact the cheapie rod seller?

Jason wrote:" And also I will check if the old bearing will fit woth the new rod. I dont think it does if I recall correctly."

Then I will assume the new rod has an undersized small end ID.

Did you contact the cheapie rod seller?

The old bearing does not fit the new rod. And I have been trying to contact the guy from ebay but he is not texting back.

I want to get better measurements tomorrow but roughly this is what I got, this is as accurate the meter can read, not sure if its enough:

New Rod:
0.79" ID
1.11" OD

Old Rod:
0.80" ID < Makes sense
1.09" OD <The outside of the old rod is very worn

The Wrist Pin is 0.63" OD, the bearing is 0.81" OD on the edge and 0.76" ID Directly down the middle & 0.61" ID. For the needles i got 0.10"

Makes more sense because when the bearing is in the rod, the pin wont go through through by just a pinch to little space. So we have settled that is has to be the small end bore of the rod correct? From here would I be better off converting it to bronze busher bearing or boring it?

To answer that question, you need more precise measurements. Two place decimals are not enough.

If you really do have an undersize rod bore, depending on the amount of undersize, you may be able to just lap it out using fine lapping compound. I wouldn't pursue this method if the amount of undersize is more than .002" or thereabouts.

To learn more about lapping and honing processes, do a Google search so you understand the processes and differences. Lapping can be done with just a split wood dowel, and some fine lapping compound. Old time gunsmiths used this method for sizing rifle and shotgun bores. With either process, the goal is a true cylinder bore parallel to the crankpin centerline. A bore that's barrel or dumbbell shaped, or going off at an angle is no good. The bore also needs a smooth enough surface suitable for a bearing race.

pumpguy wrote:To answer that question, you need more precise measurements. Two place decimals are not enough.

If you really do have an undersize rod bore, depending on the amount of undersize, you may be able to just lap it out using fine lapping compound. I wouldn't pursue this method if the amount of undersize is more than .002" or thereabouts.

To learn more about lapping and honing processes, do a Google search so you understand the processes and differences. Lapping can be done with just a split wood dowel, and some fine lapping compound. Old time gunsmiths used this method for sizing rifle and shotgun bores. With either process, the goal is a true cylinder bore parallel to the crankpin centerline. A bore that's barrel or dumbbell shaped, or going off at an angle is no good. The bore also needs a smooth enough surface suitable for a bearing race.

Alright, right now where I live (Rhode Island) theirs a snow storm. Ill give them a call as soon as possible. Im not a noob at rebuilds but when numbers get this technical I get a little lost. So basically, when I call/visit the machine shop what should I ask? If they can measure the ID of the rod? OD of the pin? I want to get all the information possibly needed in one go. I also want to see how much they will charge to even bore and hone it for me. So once I get the information I will report back, because they are going to want to know what it needs to be bored out to if possible.

I would take them all of your parts and tell/show them the issue.

They may be able to hone out the rod with everything still together (who knows?). If you take them the old rod, they can measure that and see how far the new one is off.

They also may another idea to help get you going.

Goood luck!

Put the bearing on the pin. If they fit in the old rod and not the new one, then the new one is too small.

Jason wrote:Put the bearing on the pin. If they fit in the old rod and not the new one, then the new one is too small.

Yup. Thats what I did. Now my plan is to bring the rod to a machine shop and have them measure the old rod and bore/hone the new one exactly the same.

Is the new crankshaft in the engine or still out? (crosses fingers)

Jason wrote:Is the new crankshaft in the engine or still out? (crosses fingers)

Sorry for the late response been busy, its already in the engine. I thought the bike was all set till go till it was time for the top end. Who woulda knew

Oh man. Maybe it will all work out.

Called just about every place and no one can do it. Their is one guy that said he might be able to but I don't want to depend on him and him end up not being able to do it. Im going to bring it my engine/pin to a friend and have him precisely measure it. I think I am going to have to go with the bushing bearing idea. Ill get back to yous as soon as possible. Thanks

Damn, that's tough. I don't know if 200/220 are same, but if you need any measurements let me know.
My crank s/b here tomorrow with a new pro x con rod.
Could verify oem dims or whatever I got.

Will make sure my bearing & pin fit con rod before I assemble bottom end, so an apologetic thanks

Best of luck

Just wanted to let yous know the bike is up and running. My friend was able to hone it with a Drill Hone kit picked up at napa. Runs better than ever.