Post by 90GTVert on Oct 24, 2015 8:55:00 GMT -5
Definitely not taking the stator off though, it seems like there's enough room to cut into it with the stator still attached.
You should be fine doing it that way. Sometimes I just like having more room to work.
it was recommended I open the exhaust valve a bit more to .005/.006 so more air can get out through the exhaust, what are your thoughts on this?
My first thought is that whoever told you that may not know what they're talking about. If you wanna push your exhaust valve lash up to 0.005", that's OK. I usually like about 0.003" on mine. Just don't set the clearance wider to increase flow. Every thousandth that you add to valve lash takes a thousandth off of your valve lift and slightly decreases the duration for that lobe. Don't go setting it to zero lash, because you do need a small gap.
And a question to 90GT, what exactly is the definition of peak torque and peak RPM so I know what to be looking for when I'm tuning the CVT?
Peak torque would be the rev point at which your engine makes the most torque. Peak horsepower is the RPM where it makes the most horsepower.
Peak torque is the point of greatest volumetric efficiency. That's when you have the best cylinder filling. For example, 100% volumetric efficiency (VE) would be when a 49cc engine ends up with 49cc of mixture in the cylinder. The more mixture you can cram in there, the more mixture you can burn, and the more force can be applied to the piston. Max VE is not necessarily 100%. It can be more or less, depending on the engine. Regardless of the actual percentage, your maximum cylinder filling should coincide with peak torque. Horsepower is basically a measure of torque over time.
Say your engine's peak torque is at 6500RPM, but it revs out to 8000RPM and keeps pulling well. Because of the cam and intake and exhaust components, you aren't seeing maximum cylinder filling on each revolution by the time you push 1500RPM beyond peak torque and volumetric efficiency. Because the engine is spinning faster though, it produces more power as long as cylinder filling is sufficient and it's burning a large volume of air and fuel over time. So at 6500RPM you may fill the cylinder with 49cc of mixture each revolution. That would be 318,500cc or mixture per minute (49cc x 6500RPM). If you spin the engine to 8000RPM and it's able to burn a lesser 40cc each revolution, you'd be burning 320,000cc of mixture per minute and actually processing more mixture per minute and doing more work in a given time.
This may be confusing. I'm not great at explaining it. Honestly, it doesn't matter at all if you precisely understand the concept. You can find lots of explanations online and in print much better than what I've said if you do wish to pursue a better understanding of HP and TQ though.
What you really are looking for when tuning is quite simple. You are looking for the best performance. Unless you have a dyno graph to show you where peak TQ and HP are located and a tach to help you keep RPM in that range, all you need to do is figure out what RPM range works best for your scooter. What RPM range makes you go the quickest or fastest?