To All who have installed the no longer available Orient Express valve springs:
I discovered this mess when I pulled my valve covers to fix a minor leak.
![Automotive tire Automotive wheel system Gas Rim Auto part]()
![Kitchen utensil Household hardware Nickel Screw Auto part]()
![Automotive tire Automotive wheel system Gas Rim Auto part]()
![Kitchen utensil Household hardware Nickel Screw Auto part]()
Turns out all 8 sets of inner valve springs were broken. The engine seemed to run fine, but would blow a little smoke on heavy throttle. I thought it was just a bit rich on the tuning. The broken valve springs messed up the valve seals, and even gouged a couple of the tops of the valve guides. I investigated a bit. In my opinion, the Orient Express springs were a very poor application. The inner diameter is too big, so the springs center loosely. On top of it all, the combined pressure of the inner and outer springs is barely more than stock springs. The only benefit is that they allow higher lift before binding. Which, as it turns out, is only helpful on the old Orient Express cams. The Speedstar cams don’t have enough lift to need them.
This bike was never raced. An occasional spirited run through the gears, but no rpm abuse.
And, as I’ll detail more on another post, the Speedstar springs bind at the same height (maybe worse, since they are higher rate, thicker wire.) So, it’s ok to use the OEM Yamaha valve springs with the Speedstar cams, but not the Patrick Racing or Orient Express cams. At least, we don’t have to worry that they would bind. It’s another issue that the spring pressure might need to be higher on high compression engines to keep the valves seated on the intake stroke.
Pull your valve covers, now!
Bob
I discovered this mess when I pulled my valve covers to fix a minor leak.
Turns out all 8 sets of inner valve springs were broken. The engine seemed to run fine, but would blow a little smoke on heavy throttle. I thought it was just a bit rich on the tuning. The broken valve springs messed up the valve seals, and even gouged a couple of the tops of the valve guides. I investigated a bit. In my opinion, the Orient Express springs were a very poor application. The inner diameter is too big, so the springs center loosely. On top of it all, the combined pressure of the inner and outer springs is barely more than stock springs. The only benefit is that they allow higher lift before binding. Which, as it turns out, is only helpful on the old Orient Express cams. The Speedstar cams don’t have enough lift to need them.
This bike was never raced. An occasional spirited run through the gears, but no rpm abuse.
And, as I’ll detail more on another post, the Speedstar springs bind at the same height (maybe worse, since they are higher rate, thicker wire.) So, it’s ok to use the OEM Yamaha valve springs with the Speedstar cams, but not the Patrick Racing or Orient Express cams. At least, we don’t have to worry that they would bind. It’s another issue that the spring pressure might need to be higher on high compression engines to keep the valves seated on the intake stroke.
Pull your valve covers, now!
Bob
