Do TP Rocker Boxes cause valves to break?

[BadBrad]

I just had the exhaust valve break causing catastrophic results with the rear head, jug, piston and possibly the crank/connecting rod. I called S&S and they informed me that BDM used TP Rocker Boxes on my '05 Pitbull and they have had valves break due to impropper contact points on the valve. Has anyone else heard of this? I'm new to the "Dog" world and finding out the hard way. Looks like I'll be on 4 wheels for a while till I can get funds for all the replacement parts and labor.

 

[Fibersnake]

Have not heard of TP Boxes causing vavles to break as per S&S. Have heard of some of the geometry is off causing the valve guides to wear unevenly and getting excessive wear. Not hearing of an actual breakage though, for I would imagine that if you had one of the guides wearing unusal, you would have notice long before a beakage would occur, but then again anything is possible.

Was there anything else done on the bike other than stock, possibly larger cams without good springs to match??

Any unusal noises prior to breakage or did it just come out of no where. Inquiry minds want to know.

Hope that you are able to get it fixed and back on the road soon. Sucks to have that major of a failure for sure.

 

[woodbutcher]

hate to hear about this since you only just got the dog a few months ago. the statement about the weak valve springs makes sense to me. any way of talking to the previous owner about whether or not he had any work done? probably not, because that would kinda say he knew there could be a problem.

 

[BadBrad]

The previous owner showed me all work being performed by a certified BD mechanic and no additional work was done to modify the engine. There was a light tapping of a valve since the day I got it but not extreme. Other than that, just before it broke, I had some carb problems (I think) of the engine "spitting" every now and then. I would occasionaly get into the throttle but never to the red line. I thought that's what this bike was made for. I didn't buy it just for low riding. Anyway, no one ever seems to recall having a valve break off and fall into the motor. It looks like I rode a hundred miles afterwards from the head, but only about 30 seconds at most. A bummer in the summer for sure.

 

[Raywood]

The previous owner showed me all work being performed by a certified BD mechanic and no additional work was done to modify the engine. There was a light tapping of a valve since the day I got it but not extreme. Other than that, just before it broke, I had some carb problems (I think) of the engine "spitting" every now and then. I would occasionaly get into the throttle but never to the red line. I thought that's what this bike was made for. I didn't buy it just for low riding. Anyway, no one ever seems to recall having a valve break off and fall into the motor. It looks like I rode a hundred miles afterwards from the head, but only about 30 seconds at most. A bummer in the summer for sure.

Check Dakotabos' thread on his top end job. He did it himself over the weekend after ordering the right parts.
Nothing wrong with the TP topends other than some issues with the valve guides as FS mentioned.
Get the ignition down loaded and see how the previous owner operated the bike. It will tell you a lot.

 

[RCAdd1ct]

What is a ballpark cost on the hardware to replace the TP boxes?

 

[05chop]

The previous owner showed me all work being performed by a certified BD mechanic and no additional work was done to modify the engine. There was a light tapping of a valve since the day I got it but not extreme. Other than that, just before it broke, I had some carb problems (I think) of the engine "spitting" every now and then. I would occasionaly get into the throttle but never to the red line. I thought that's what this bike was made for. I didn't buy it just for low riding. Anyway, no one ever seems to recall having a valve break off and fall into the motor. It looks like I rode a hundred miles afterwards from the head, but only about 30 seconds at most. A bummer in the summer for sure.

Depending on which valve and where it (broke) separated can happen if the valve set is off. When the rocker slaps the valve stem for extended time can cause a valve to fail. Pictures of all the failed parts do have a story to tell! Rev hits from the EHC should of told where the RPM range had been.Friction weld breaks are like you say unheard of here.

 

[BadBrad]

Big Dog returned my call today. "Doug" said that a bad spring most likely caused the failure. His suggestion was to replace the valve springs with S&S triple springs. I forgot to ask what springs come stock in the head. The set costs about $110. To answer a couple of previous questions, the valve stem broke inside the sleeve at the base of the sleeve. The failure occured in the rear cylinder. Doug (BD) also stated that the geometry of impact on the TP rocker boxes is slightly off and suggested buying S&S rocker boxes for a truer geometry. Too late. I found a complete upper end on Ebay from a BD 117ci test bike with less than 2K miles. The set includes both jugs, pistons, new rings, complete heads and rocker boxes. I paid $850 for the lot but only need the rear set. I guess I'll list the front set back on Ebay and try to re-coup some of my costs.

 

[woodbutcher]

i think i would go ahead and use as much of the new stuff as i could so as not to leave a weak component in the system. then maybe sell some of the old stuff on ebay. :zz2cents:

 

[prodiver]

I had the same thing happen with my 06 Mastiff at 12 k the rear valve broke and tore the cylinder and piston up. This put a lot of crap into the lower end. Sent the motor to S&S for a rebuild and got S&S rocker boxes. This bike was never over revved or even rode hard and the motor only lasted for 12k. I am still breaking in the new motor and I hope it lasts longer then the last one.