bikepilot

It is possible to make big HP on a low maint schedule, but hard to do it on a big na push rod 2 valve moto because you have to use such extreme cams to get them to breathe. Other engines use two cams with the can lob pushing directly on the valve. Done right this can flow very well with relatively modest cams and the can only has to move the valve so less weight to control. As an extreme example a performance motorcycle makes up to 200hp/liter stock and I've yet to see o e wear out! I imagine this is a big part of why merc went for a four valve head on their high end motors.

Drew555

very true. I've raced motocross for years... Back when they were2 stroke motors..... No valves. You could ring the nuts out of them. Now with the 4 strokes you can still ring them out but there made to have the power at the bottom end. ( use the torque) for power. They still turn up to 13 k rpm and above with over head cams. As far as the hp motors +/- " black" motors. ... If you want more power= more fuel = more air= more rpm = more rotating mass= fast and lots of $$$$$ hahaa! But that's why we do it anyway. So just pin it and hold on

Cole2534

iTrader: (1)

Because big power equals big stress and as you approach something's ultimate stress its fatigue resistance falls. Eventually the fatigue line and stress line meet, and that's when 1 piece objects become 2 - 3 - 4 - infinity piece objects.

payuppsucker

I thought we'd already discussed the issue of you holding back, or withholding. Or was it withdrawing? No, now I'm thinking we talked about pulling out. What was the question?

Drew555

Never hurts to freshen up valves. Your power will start to drop off year by year. If you freshen up the valves, springs etc you can be back to original speeds for a few $

payuppsucker

As components are added and changed to achieve the desired power, each part involved is subjected to more stress. The parts are manufactured to be functional, marketable, but only reliable enough to hold their share in their particular market or niche while keeping production costs within margin. Without a doubt the perfect or near perfect powerplant could be designed and manufactured to make any given horsepower and last as long as 10,000 hours provided money was spent without discretion. Every part that moves on and automobile has a built in failure rate. They are engineered to fail at so many hours or a given number of cycles or actuations plus or minus a certain percent. Parts could be made to last forever but they'd be expensive and the manufacturer would go out of business. I think I got off track somewhere so I think I'll stop here and get another IPA and let SB finish because I don't remember the question. He's probably not drinking tonight.