meatness
Well-known member
I picked up a little ATV for the wife. She has wanted one for a while and I figured I would pick up a project that me and the boy could work on.
The quad is a Kawasaki Mojave KSF250 from the 90's. After doing some research I have found two common fail points for it. The kickstart idle gear and reverse shaft gears like to fail and the valves like to tighten up. Okay that may be three things. Of course so far the one I picked up has at least the kicker problem.
Here is the issue.
The idler and the reverse shaft gears are held onto their respective shafts with c clips. They both ride on a brass bushing that is lubricated via oil flying around in the crank case. The bushings fail causing all kinds of issues.
Here is the crank case and the placement of the gears. Notice the gap between the reverse shaft gear and the shaft. This is because the bushing failed and is now missing.
The idler gear shown in this picture is a new gear I purchased to replace the failed idler gear pictured a few below.
Here is a close up of the shafts and the placement of the C clips that hold the gears in place.
This is a reference of where the shafts are in the motor overall.
Here is the original failed idler gear. I did notice that the replacement idler gear is a little different, the gear is wider overall with a wider bore to ride on the shaft. I am thinking that this was Kawasaki's fix for this known issue.
Failed c clip
The 3 gears that I have from left to right, failed Idler gear, replacement idler gear with new bushing, and failed reverse shaft gear.
This is the reverse shaft gear close up. Notice some of the bushing is still crudding up the gear from the failure.
This is a close up of the new gear with the good bushing.
Now here is where I need advice. How would you go about fixing this issue so that it will
A. Not cost a small fortune and
B. Not fail again.
My ideas are this. Machine out the gears to fit a Drawn Cup Needle Bearing that has the correct width and ID to fit the shaft accordingly. I see two issues with this, the cost of machining the gears to fit the bearing and finding bearings that would fit my application. So far after about an hour spent on Grainger on a few others I haven't found anything that would work.
The dimension of the gears.
Idler Gear - ID 19mm exactly, width of the gear that meets the shaft is 9mm.
Reverse Shaft Gear - ID 19mm exactly, Width 7mm.
The bushing on the idler gear is 2mm thick making the shaft 17mm OD on both gears.
The other idea I had was to just fit the new/wider gear hoping that this was indeed a good enough fix and find some material that would work as a bushing for the Reverse Shaft Gear. The issues with this fix are I have no idea where to source the correct material in the dimensions I need to make a bushing and I obviously don't have access to a lathe.
Any advice would be much appreciated. Thanks.
The quad is a Kawasaki Mojave KSF250 from the 90's. After doing some research I have found two common fail points for it. The kickstart idle gear and reverse shaft gears like to fail and the valves like to tighten up. Okay that may be three things. Of course so far the one I picked up has at least the kicker problem.
Here is the issue.
The idler and the reverse shaft gears are held onto their respective shafts with c clips. They both ride on a brass bushing that is lubricated via oil flying around in the crank case. The bushings fail causing all kinds of issues.
Here is the crank case and the placement of the gears. Notice the gap between the reverse shaft gear and the shaft. This is because the bushing failed and is now missing.
The idler gear shown in this picture is a new gear I purchased to replace the failed idler gear pictured a few below.
Here is a close up of the shafts and the placement of the C clips that hold the gears in place.
This is a reference of where the shafts are in the motor overall.
Here is the original failed idler gear. I did notice that the replacement idler gear is a little different, the gear is wider overall with a wider bore to ride on the shaft. I am thinking that this was Kawasaki's fix for this known issue.
Failed c clip
The 3 gears that I have from left to right, failed Idler gear, replacement idler gear with new bushing, and failed reverse shaft gear.
This is the reverse shaft gear close up. Notice some of the bushing is still crudding up the gear from the failure.
This is a close up of the new gear with the good bushing.
Now here is where I need advice. How would you go about fixing this issue so that it will
A. Not cost a small fortune and
B. Not fail again.
My ideas are this. Machine out the gears to fit a Drawn Cup Needle Bearing that has the correct width and ID to fit the shaft accordingly. I see two issues with this, the cost of machining the gears to fit the bearing and finding bearings that would fit my application. So far after about an hour spent on Grainger on a few others I haven't found anything that would work.
The dimension of the gears.
Idler Gear - ID 19mm exactly, width of the gear that meets the shaft is 9mm.
Reverse Shaft Gear - ID 19mm exactly, Width 7mm.
The bushing on the idler gear is 2mm thick making the shaft 17mm OD on both gears.
The other idea I had was to just fit the new/wider gear hoping that this was indeed a good enough fix and find some material that would work as a bushing for the Reverse Shaft Gear. The issues with this fix are I have no idea where to source the correct material in the dimensions I need to make a bushing and I obviously don't have access to a lathe.
Any advice would be much appreciated. Thanks.
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