| Author | Message | ||
     Sqbuell |
I recently built an 1190 drag bike out of a 08 1125r. DME Chassis setup and all. 1190 EBR kit, Crower cams, CycleRama did the heads. Broke a follower on the dyno at 8000rpms. Is there a chronic follower problem? Also are the KTM parts a cross over? Thanks Vance | ||
| Nikoff90 |
You should email EBR tech support, my experience they are very helpful and quick to respond. | ||
| Sqbuell |
Funny you suggested that. I just got a text from Michael Ricter at EBR. Thanks, I'm still interested if others have had followers break. Vance | ||
| Stirz007 |
I've broken 4 of them, but the cause was jumped time (chain gear slipped on camshaft resulting in about 15-20 degrees out of correct timing), causing intake valves to slap piston. I broke two, replaced them, then broke them again before it occurred to me to pull the head - then I found the problem. Normally, from what I understand this is somewhat rare. Were the cams higher lift than stock? - after reinstall of new cam followers, you may want to hand rotate motor to make sure you aren't getting valve/piston interference. I've got decked heads, so my tolerances were tight to begin with. | ||
| Sqbuell |
Thanks Stiz007. I didn't assemble the motor. The cams were modified by the base circles. Lost one valve and valve guide. The bike is at Rossmymer's HD. Their Buell guy who worked on supersport bikes is working on it and dyno tuning as well. The cams were indexed when assembled. | ||
| Stevel |
Sqbuell, You stated you are using Crower cams. Are they new or reground Originals? I would very much like to know the cam profile specs, if you have them. I wish to acquire new cams as well, so your specs would be helpful. I would like to point out that reducing the base circle diameter on the Buell design changes the valve geometry significantly and this geometry change must be compensated for very carefully. Please keep in mind that the valve shim is retained by close contact with the finger. The new profile most probably has faster ramps and higher lift. The reduction in base circle was likely compensated by thicker shims increasing valve inertia possibly beyond the ability of the valve springs to prevent float, potentially allowing the shim to jump out of the seat in the spring retainer jamming the assembly and fracturing the finger follower. I suggest this is the most likely failure mode, as there is insufficient forces to cause failure without float. Secondly, adding additional spring tension with all that drive chain is dangerous without very careful bench testing. Reducing valve mass is the way to go first with titanium valves and retainers. | ||
| Sqbuell |
Stevel I agree with you about the base circle. Bigger shims were supposedly used. I think youre right 100%. Crower sent the cams back to Wes Brown at Cyclerama with little info on a hand written piece of paper. I suggest buying 1090 RX cams from EBR. This is a expensive learning curve and waste of time. I've already missed one race out of four. If you want to talk more use Houdyshell@comcast.net I can send pictures there or try my facebook Vance Houdyshell. | ||
| Sqbuell |
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| Battyone |
I've only broken followers when spitting shims!!! So not at 8000, more like 12,000 1125 doesn't need cam work for drag racing, the required rpm band is so high and narrow - 9k to 11k and as flow testing has showed the port shape is the restriction at those levels. Littlebutquick has had two attempts to build quicker/faster motors but still goes quicker than anyone else on a stock motor! Weight and airflow up to 70mph are the areas that need looking at to go quick. Don't waste money on cams.Spend it on mag wheels or carbon bodywork. |
