tough Road America

[TZmb]

We had our '92 4DP at Road America in an interesting Open 2-stroke field that featured an '82 RG500 Suzuki and a '7? TZ750 and damned if we didn't suffer not one but two reliability failures.
On Saturday the TZ750 pulled a 5.8" gap on lap 2. Working 2 stopwatches I got excited as the gap went down to 5.0" on lap 3 and 3.5" on lap 4 of 6. Then nothing --->the long wait. Greg had managed to pass and pull away from the gently ridden Suzuki and perhaps the TZ750 had eased but....
Turned out that we had lost spark eventually traced the proble to a failed solder connection at the source coil under the rotor. Ignition swap and fumbling timing had us running by 8:00 pm.
On Sunday Greg got what looked like an uncharacteristicly bad start only to limp into the pit with a failed clutch. After digging through our notes backtracking to baseline clutch life we found that the failed clutch had 1090 miles and 14 starts on it. We also backtracked to clutch life on engine #2 that entered the frey in 2014. That clutch got 832 miles and 12 starts before failing. So now, unless Greg can get these to fail in practice, we will track clutch mileage more carefully.

[mark28]

I have always changed plates as a service item after every weekend ( 4 Starts).I've had them slip before that but I guess it depends how hard you are off the start.

[Bud977]

Wow! I'd have over a hundred starts on the clutch on my TZ250A (basically the same clutch as a 4DP/4TW) and the plates are fine. I'm not even thinking of replacing them anytime soon.

However, I do regular maintenance on the clutch. After every race meeting, I pull it apart, check the hub nut for tightness, check the plates. Replace any broken plates or ones that show signs of slip. Usually, you catch them before it becomes an issue and it becomes an infrequent affair.

The important part is to make sure the clutch cable is in new condition and you've got adequate free play. Any kinks can prevent the clutch from fully seating. If the clutch slips for a few laps, that's it, the clutch needs a rebuild.

On the start line, wait in neutral for as long as possible. For our starting system, I wait until the red light comes on. If you wait for a long time in gear, the clutch starts to hook up and get nasty.

I have added a steel RDLC clutch plate next to the hub to give a bit more pre-load.

[gmrtz44]

Mike
I get 4 launches out of a clutch, same thing that happened to me last year at Road America, that was the 5th start and it slipped. considering the cost of a clutch pack its kind of cheap insurance
see you in a couple weeks
Darrell