KX Guru Racing

*** UPDATE 10-11-24 ***
Tom Morgan Racing TMR can put a new bushing in your gear

https://morganracingengines.com/

949-421-7112

That's right folks, 26T - FITS 86-04 KX500 - 59051-1150 is no longer avalable



If your KX500 is 10-15 years old it's likely that the bronze bushing is worn out....
Almost every KX500 Jason and I have rebuilt over the last 5 years needed a new gear and we use to simply order a new one.

What to do....
If you look closely you can see that this bushing is split.
So, I am looking for a trans gear of the same dimensions ID and OD... The width can be a little wider with no issues...
Just means a little grinding after the bushing is pressed in.

We are also working on a upgrade

OK, we also found a needle bearing that may work but that is for a later project.

In the mean time Jason and I were talking about how to solve this issue and Jason said that he wondered if one of the trans gears had the same size bushing...
Turns out that yes, first gear has a bushing ID and OD that is exactly the same.
The bushing is a little wider but that is no big deal.

Since I have a bad first gear I measured the ID and guess what? It is right on spec for a new bushing for the Idler gear.
So, I pressed out the bushing.
But since, the KX500 gears are disappearing we need to use something else.
Scroll down to the bottom to see other options.

Next, I pressed in the new bushing from the trans into the idler gear.


As you can see, it's a bit wide but a quick trip to the grinder and sander fixes it up nice.
Also, the bushing is now just a little wider then the stock bushing.

After grinding I measured the ID...
It's perfect.

I wondered why the idler gear wears out so much faster then first gear.
Jason and I discussed it and figured there has to be three reasons.
1. The idler gear is narrower and has an even narrower bushing.
2. The idler gear has a lot of side load on it where the trans has a very even load on it.
3. Potentially there is a lack of oil getting to it.

So, I was thinking about this..


Maybe... Maybe not

As discussed above you could use a KX500 1st gear output from a KX500 for a bushing.
But, since KX500 gears are disappearing fast I am looking for other gears from other bikes to see what we can use.
One piece of advice, measure the ID the bushing you want to use BEFORE you press it out.
If it's oversize before you press it out, it will be oversized when you press it into the idler gear

13260-1759 GEAR, OUTPUT LOW, 27T Fits 99-01 KX250

13129-1160 GEAR, OUTPUT LOW, 32T FIT THE FOLLOWING: 1980-1998 KX250 & 1984-1987 Tecate KXT 250

13260-1752 GEAR, OUTPUT LOW, 31T fits 1999-2005 KX125