Fine tuning carb setup

[stevenrankin]

They

Paul, they show up for sale from time to time, just bring a fat wallet.

I took a ride on one the first year they came out, what a hoot. If I had a fat wallet and space, I would have one in the garage. St.

 

[Visian]

That is what I rode to and from Alaska in 1991 while Voni rode her R80ST with a raised front fender (better clearance to dig out mud) and we both had 50-50 dual sport tires. It was a great bike which I traded in when I bought Voni Big Red (R1100RS) for Mother's Day in 1993. She still has and rides Big Red. I wish I still had my R80G/S.

I did not know that, Paul. I was going to ride mine to AK in 98 but my friend bought a new oilhead R1100 and... if my airhead were to break down I would never live it down. So a new oilhead it was for me!

 

[lkchris]

Couldn't find in original or any response whether the air injestion system remains installed on this bike. The metal pipes from airbox to cylinder head.

Purpose of that system, of course, is to introduce oxygen to complete combustion--in the exhaust system--of any unburned fuel, which would otherwise be considered pollution if it exited the exhaust system unburned.

This process is a source of popping.

It doesn't really do much to mess with main jets on these bikes, except to make them perhaps overly rich, meaning more unburned fuel in the exhaust.

Some think they compensate for altitude with main jet changes, but he fact is these CV carbs by design automatically compensate for altitude since the vacuum effect on diaphragms that raise the needles is changed by altitude. Bing's other business is carbs for general aviation. It's a big laugh to almost everyone, but Bing recommends annual replacement of diaphragms. In fact, you could probably skip all the o-rings, etc. and just replace diaphragms and you would have essentially "rebuilt" your carbs. Oh, BTW, all that fuel/aiir rushing past the needles causes the needles to wear. Periodic new needles not a bad idea.

If you've modified from original compression (8.2) to 9.5, the carb change to match would be one notch richer for needles.

PS: most of the time this emissions solution is called air injection ... because there is often an electric pump to accomplish it. Another euphemism seen is "secondary air." I use injestion, because on these bikes the air isn't pumped into the exhaust, it's just drawn in by rushing exhaust.

 

[Visian]

And here I thought those tubes were for exhaust gas recirculation. Hmmmm, learn something new every day.

When the tuner built my bike, he removed those tubes and plugged the holes with drain hole bolts. I can’t say whether this mod specifically made a difference because a number of other mods were done simultaneously.

Can’t wait to get my rebuilt carbs back.

Last, interestingly, the Bing website makes a BIG deal about their warranty and liability of using the parts they sell for Aviation applications. Oh, and I wish they would get a good technical writer to brush up their manual!

 

[pglaves]

And here I thought those tubes were for exhaust gas recirculation. Hmmmm, learn something new every day.

There is an old saying: "The solution to pollution is dilution"

Which way the air flows through the tubes is significant.

What that system did was draw fresh air at the air box and direct it to the exhaust flowing downstream from the exhaust valves. As the exhaust flows, something akin to the venturi effect causes the air to be sucked to flow to the head. This injection of fresh air (including oxygen) would cause some combustion of unburned fuel in the exhaust, and it would also dilute the exhaust flow so pollutants measured at the tailpipe seemed less because what was being measured was a combination of exhaust gasses and fresh air.

I always wondered why people figured this system had an effect on performance. Injecting air into the exhaust stream after it has passed the exhaust valve doesn't seem to me to have much if any affect on the running of the engine. But as we all know, tinkerers have to tinker.

 

[stevenrankin]

Air injection

I ran my 84 R80RT's air injection system from day one to last winter. Then I pulled it off and plugged it. The reason was not performance related, rather the tubes to the heads had developed holes. LOL, it was cheaper to buy plugs and plug things rather than replace them.

I see NO difference in MPG, or performance. Ascetically, the engine looks cleaner. St.

 

[20774]

Snowbum describes the Pulse Air Injection system on this page:

https://bmwmotorcycletech.info/pulseair.htm

 

[Visian]

There is an old saying: "The solution to pollution is dilution"

That's somewhat like "there is no replacement for displacement"

Maybe someday it will be "ain't now power without kilowatt hours"