mmosel wrote on 08/23/11 at 00:51:51:


What is it doing that you interpret as "running lean. I can feel it, I can hear it." ??

The only real danger from running lean is detonation.  If it is not pinging, you are okay.  Trouble is, sometimes light detonation is not very obvious.  If you think it might be pinging even slightly, use premium gas for a while until you get the mixtures right.

Running lean may cause inconsistent combustion which can cause less-than-smooth operation,.. just like a stock late model Savage.  They come from the factory on the ragged edge of lean mixtures, so you running yours even leaner won't be that much different,.. just a little cooler.

CHT is maximum at 14.7 air/fuel ratio.  (stoichiometric)   When mixtures get leaner or richer, temps go down.  There are some factors that can modify this just a little, but generally if you run lean or if you run rich, CHT goes down.  EGT may go up, but not much gets harmed with high EGT.

Wow, I ordered on the evening of the 24th from Nichecycle and I received the jets today. I was expecting to get them by the end of the week!

Now I can put her back together again...

I just read not to long ago on the internet the reason newer cars will go a lot more mile than they did years ago in because with fuel injection your not to lean in the winter and not to rich in the summer. Your always at the right mixture.

bill67 wrote on 08/29/11 at 18:54:32:

Well that along w/ slower piston speeds, hotter running temps, and better oils, and other stuff, I agree.

So lets get after it !!

Wouldn't that be neat,.....a bolt on EFI kit for.........anything, not just our bikes. I have often wondered,....this day and age, why don't we ever see after market EFI. They make everything else !

 
Mixture too lean

Combined with a high power setting this will result in high cylinder temperatures, possible detonation, very hot or burnt exhaust valves and maybe damage to the pistons resulting in a power failure and a possible off airport landing.


Just read it for what it says -- mixture too lean at wide open throttle will result in higher cylinder temperatures.  Detonation is easy to explain when the valves get anywhere near hot enough to burn (cherry red) and aluminum pistons can get soft and blow out in those conditions as well.

It's not like we haven't seen a holed out piston here on the list -- luckily they are pretty rare things.

Damage to piston ring areas (galling coming up the front of the pin bosses up into the ring area) is a lot more common, unfortunately.   Most teardowns on high performance engines have this problem.

You make a good point though, Suzuki sets the bikes up pretty lean in all the later years to meet EPA target standards and then we yank off the restrictive stock air filter and exhaust pipe (lowering intake vacuum levels) then run the immortal piss out of the more powerful engines, not realizing that we might be gas starving the engine at full throttle because our vac petcocks were designed to work at the original stock filter intake suction levels.

And that's before the petcock gets old and its performance declines.

You could say rejetting is a performance and reliability enhancer.

Routy wrote on 08/30/11 at 05:22:10:

There's aftermarket FI, just not bolt-on for any particular bike. A couple of guys have converted their DR650s to FI and were asked if they were interested in selling kits.. not interested.  It is an expensive proposition for diehard tinkerers who would want to hand-select each individual component (and not pay a middleman) anyway. Anything can be FI'ed with enough brainpower and tenacity, though.  I have a friend who built one of those Velocity kitplanes and plumbed up a 6-cyl Franklin from scratch.. ignition, FI, sensors, electronics, full logging.. guy's a genius.  Unfortunately the engine crapped out on the plane's maiden flight and he had to put it down in a cornfield.. currently rebuilding.

It is interesting to note in Gyrobob's graph that on the far lean side, specific fuel consumption begins to go back up.  It is good to be slightly lean of 14.7 so that there's enough air to scavenge for fuel molecules, but push it too far and the engine loses efficiency by huffing extra air around for no good reason.

In europe, Audi/VW came up with (I think) what was called K-Jetronic back in early 80's, in VW golf rabbit. Mechanical fuel injection, no lambda (02 sensor) , no ECU... It can be done... but it takes a lot of trial and error.