KDXRIDER.NET

Hey, look I split the cases, rebuild crank with RB designs, put cases back together like butter, and long story short I ran in to a brick wall. I went to the top end assembly stage. I went to install the bearings/pin to the top end of the rod and they do not fit. The bearings do fit in the rod alone, and they do fit the pin alone. But when the pin and the bearings are together they do not nearly fit into the rod. I don't know what to do. The rod I bought was off eBay, I will put a link > http://m.ebay.com/itm/Kawasaki-KDX-200- ... Ciid%253A1

Yes I know it is a cheaper rod kit. Don't kill me lol. The piston I bought was ProX. What should I do? Is their any where I can buy an pin that is a bit smaller than the ProX one I have? WELP!!

Are you sure that you're using the right pin? Have any photos of the parts you are using? Seems odd, might just be missing something...

Welcome to the forums. Is this your bike, or are you someone working on someone else's bike?

Have you contacted the seller to ask him how others got along?

Does the pin fit the piston?

Tyl3r wrote:Are you sure that you're using the right pin? Have any photos of the parts you are using? Seems odd, might just be missing something...

I am positive i am using the right pin. I just took some photo's of everything but can't figure out how to upload them on this site

Post them on photbucket then link them hereusing the IMG tags

We don't have ads to make money to pay for the space to host a ton of pics. The site stays open on donations.

Jason wrote:Welcome to the forums. Is this your bike, or are you someone working on someone else's bike?

Have you contacted the seller to ask him how others got along?

Does the pin fit the piston?

It is my bike, the seller is long gone now I have no way to contact him and the pin does fit the piston. I bought a ProX piston kit it needed and it comes with 1 piston, 2 c-clips, 1 pin, and 1 top end bearing. I have pictures but as I said I cant figure out how to upload them

Jason wrote:Post them on photbucket then link them hereusing the IMG tags

We don't have ads to make money to pay for the space to host a ton of pics. The site stays open on donations.

Alright will do, gimme a sec. Thanks for the quick response

http://s86.photobucket.com/user/josefre ... 7/library/

Their should be enough pics

You should measure old rod small end ID, old piston pin OD, bearing inner and outer dimensions on the holder portion, then compare to the new parts.

I wasn't able to open your pics.

Do you have or know someone who has precision measuring tools; micrometer and telescope gauges? If yes, I would suggest measuring the various ODs and IDs and see where the interference is.

No I don't know anyone with those kinds of tools, ill look around at the local machine shops and see if they can help

Do you have all the old parts??

Mix and match to see what changed.

Grab some small items and try to compare them to it to somehow see if something is different. Do you have a ruler or tape measure?

Does the old bearing work with the new pin in the new connecting rod? My best guess is the connecting rod is slightly undersized, but without measuring it, its hard to say. You can get a digital caliper from harbor freight for like 10 bucks, then you can take some measurements of all of the fits on the new and old parts and find exactly which piece is the problem.

Yea I do have all of the old parts, ill try mismatching and comparing tomorrow. And also I will check if the old bearing will fit woth the new rod. I dont think it does if I recall correctly. It may be under sized but I will make sure tomorrow. I will also see if I can grab the digital caliper. What happens if it is undersized? Is it possible for me to get a slightly smaller pin? The bearings fit in perfectly but both the bearings and the pin wont fit at the same time. Yous dont know how much I aprreciate all your guys help.

Does the pin look like it will fit in the piston?

Jason wrote:Does the pin look like it will fit in the piston?

Yea the pin does fit rhe piston. It actully came with the piston along with the bearing. But the pin might be to big for this specific rod kit maybe?

As much as I hate to say it, It really seems to me like the rod kit is wrong... If the rod bore is undersized, it could be too small for the bearing, regardless of how you modify the pin.

Tyl3r wrote:As much as I hate to say it, It really seems to me like the rod kit is wrong... If the rod bore is undersized, it could be too small for the bearing, regardless of how you modify the pin.

Wouldn't I be able to buy a modified bearing/pin that will fit the rod? Theirs no way I can take this whole build back apart

This may sound like heresy, but if you don't want to do a complete teardown and fit the correct parts, you could go with an easily (relatively) made bronze bushing instead of the needle roller wrist pin bearing. The bushing would need to be a press fit in the rod bore, and have running clearance for the wrist pin.

Many high performance 2 stroke bike and other engines use(d) a bushing for this bearing including my 2 Maicos. You may need to add lubrication holes or a slot to the rod's small end. Back in the day, I even used an Oilite bushing for this application.

To arrive at proper dimensions, precision measuring tools and a lathe will be needed.

If measurements show the problem to be the rod has an undersize small end bore, and depending on how undersize it is, you may be able to have the bore honed out to proper size.

Keep in mind that this is a case hardened bearing race surface, and if too much is removed, the surface will be soft and not suitable for a bearing race. A typical case depth is .005".

As advised earlier, precision measurements of the parts is needed to determine what part is wrong.

Donovan401 wrote:

Tyl3r wrote:As much as I hate to say it, It really seems to me like the rod kit is wrong... If the rod bore is undersized, it could be too small for the bearing, regardless of how you modify the pin.

Wouldn't I be able to buy a modified bearing/pin that will fit the rod? Theirs no way I can take this whole build back apart

If you got a modified pin, it would have to be smaller in the center, and larger at the ends... you wouldn't be able to push it all the way thru from on side of the piston to the other... it would hang up in the bearing when you went to push it thru.

But still... we really don't know with 100% confidence which part is the culprit here.

If you went with a custom sleeve bearing (as pumpguy) mentioned, I don't know how you would determine the proper running clearances to have one made I could see that as being a nice upgrade tho if you could figure out how to make it work.

Where did the bearing come from? Maybe that's the piece that's wrong? I have a new Wiseco one at home, but I took a look at it and didn't see any part numbers scribed into it to help with identifying the size. I have seen cheap Chinese bearings come in at work that did not match the manufacturer's published specs. You never know....