thank you,
if this is caused by richness in the main jet, why does it not happen with the end cap on? opening up the exhaust SHOULD make everything leaner right? also why do i have so much more power with the cap off? i know 2 strokes an expansion chamber to increase compression, now i should have less compression (because of less backpressure) so less power but that's not the case
so there is no harm caused by prolonged full throttle 4 stroking? (expect the oblivious wear and heat that comes with keeping a 2 stroke at peak rpm)
would going leaner increase top speed or would it still top out at the same speed?
for tuning, is the plug-chop actually accurate? i see so many mixed thoughts about it. my ducati monster and bmw f650 are perfectly jetted (dyno) and the sparkplugs look very lean (pretty much completely white)
so i'm wondering how accurate it can really be, some say due to fuel additives and cleaners it's not reliable like it used to be back in the day.
also can a plug chop be done with a rich oil-gas mixture? i'm still using the recommended break-in period mix, i'm wondering if the extra oil would make the plug chop reading even more inaccurate.
sorry for all the questions!
i build this bike around 1-2 years ago and after using it for a while i just left it there with no time to work on it.
however i'm motivated to get back on this project.... i'm planning on making tons of improvements
disc breaks, saddle with shock absorber, spring-tensioned chain tensioner, and a bunch of other stuff
then perhaps i wanna work on performance a lil bit, what are the biggest performance mods on these engines(especially cheap ones, not planning to spend a lot as i trash this bike off-road and have tons of fun with it)?
You are getting more power, because it is breathing better. You are not really looking for " back pressure", but an acoustic wave. The wave is what stuffs the fuel back into the chamber, adding to dynamic compression. When you took the pipe off, you reduced the " back pressure", allowing it to breathe better. Allowing more exhaust gases to escape and not to be stuffed back into the chamber, reducing the available fuel to burn. By opening it, its running better, because it can push those gases out, and stull draw in a good charge, because there is less stopping the fresh mix from bottle necking. You will have a lower dynamic compression, but with more fresh fuel, it helps to make more power.
Prolonged 4 stroking will just foul the plug and build up a bit of carbon. The engine will probably stop running from the fouled plug, long before any of the carbon become a problem in the cylinder.
Leaner doesn't mean more speed, you will still have the same top speed. Your speed is determined by your gearing for the most part. An that will not change if you have more power, you will just have more ability to climb inclines.
No one does a plug chop correctly anymore. It is called that, because we used to actually chop the plug in half to read it. Now people just look at the color on top for the most part. Which is only half the story.
Your ducati and beamer are 4 strokes, an most likely liquid cooled. A liquid cooled engine will never see temps an air cooled engine will see. The cooling system allows them to run leaner without damaging components, because it is the heat that kills it. The cooling system takes away the heat faster and more of it, than just blowing air across some fins.
Even with extra oil, you should still get a nice cocoa color. You are not trying to burn the oil, just the fuel. The oil exits as a high temp vapor and some liquid, carrying away carbon and debris from combustion. Extra oil will help make more power, by sealing the rings better and helping keep it cooler by reducing friction. As long as your fuel to air ratio is correct and the right plug temp range, your plug will still look good, unless you like to idle a lot, then it will foul out from all the extra oil.
Never be sorry for asking question, it's why we are here. We want you to learn, grow, and smile while riding your MB. So please, feel free to ask all the questions you need to get going and understand your engine. No one here will ever knock you for asking questions, it's a sign of being intelligent.