Originally Posted By: Spazdog
Originally Posted By: boraticus
Originally Posted By: Spazdog
I think the redline on my old RD350 was 8500. Which really seems kinda' low. Especially by today's standards. But when you think about everytime that piston goes down, it's a power stroke, that doesn't seem so bad.
The stock RPM red line of 8500 on the old RD350 is a bit conservative. Many of the old two strokes are still around and a lot of them are used in certain forms of racing. The RD350 in race trim is often run past 11000 rpm but that's getting close to the limit of what the engine can handle. Speeds beyond that can cause the piston crown to separate and main bearings to cook. Racers prefer to use main bearings from the Yamaha factory racers (TZs) to cope with the higher rpms.
Accordingly, modern two cycle engines shouldn't have any issues running wot provided they have adequate lubrication and cooling.
With just expansion chambers and rejetted carbs, my RD went north of redline many times without incident. I don't remember running it to 11,000 rpm but certainly 10,000. I had to keep up with a CB750F and a KZ650
(another friend had a snot green CB350 Four...we ran away from him pretty easily. Even so his 350 Four and my old "RingDing" 350 are on the big list of bikes I wish I could have)
Something of importance I don't see mentioned...
There is a BIG diff between MAX RPM and PEAK H/Power & Torque..
While these engines may very well rev above 10K I assure you they are NOT making anymore power at 11k then they are @ 10k..
While the idea that more revs means more power is a popular notion once in reality it's not true.. Once peak power is made more revs nets you zero. At that point your quite simply applying stresses to the engine unnecessarily.. While in certain applications over-rev is useful (holding a gear into or out of a corner while racing for example) in most instances it's just shortening engine life..