rear pipe glowing
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
If your plugs are not bone white and your ign isn't way out you'll be fine.
I would make a point of strobing your ignition though...with your set up I would time it to the stock marks and not mess with it, use whichever advance curve you like but it needs to end up at the same place.
I would make a point of strobing your ignition though...with your set up I would time it to the stock marks and not mess with it, use whichever advance curve you like but it needs to end up at the same place.
Grand HDF Member
Joined: May 2008
Posts: 4,328
Likes: 3,614
From: Picayune, Ms.
Actually your engine is in perfect tune, don't do anything.
What you are seeing is the result of a "RICH" mixture in the rear cylinder(normal) and on hard acceleration, or continuous high speed the mixture is burning(relative term here) in the exhaust. Exactly what it is suppose/should do. Therefore causing the rear pipe to glow. Now if it was the front cylinder then you would have a "LEAN" problem. The rear cylinder then would be on what is called the high side of lean and actually be cooler than the front for lack of fuel.
After years of flying P&W R-985's with EGT gauges this is easily explained and understood.
On a side note, this is why the rotary engine can't pass emission test, there isn't enough time in the exhaust cycle to completely burn the fuel, it cools off to soon after the exhaust port opens.
If the exhaust pipes were short enough or there wasn't a muffler then it would be easy to adjust mixture on our bikes.
from rich to lean it would look like this:
Orange attached(to the pipe end, way rich)
red attached(just rich)
blue attached(best mixture)
blue transparent(going lean)
blue unattached(over lean)
If you ever watch the movie "The Spirit of St. Louis" with Jim Steward there is a scene where they show the engine at nite, note the flame is not attached to the exhaust pipe. That was because he was running the engine over lean for best fuel burn.(least fuel consumption)
At any rate all this boils down to, you won't hurt the engine. The true indicator of what is going on will be the spark plugs, just make sure they are the correct heat range and the correct gap.
What you are seeing is the result of a "RICH" mixture in the rear cylinder(normal) and on hard acceleration, or continuous high speed the mixture is burning(relative term here) in the exhaust. Exactly what it is suppose/should do. Therefore causing the rear pipe to glow. Now if it was the front cylinder then you would have a "LEAN" problem. The rear cylinder then would be on what is called the high side of lean and actually be cooler than the front for lack of fuel.
After years of flying P&W R-985's with EGT gauges this is easily explained and understood.
On a side note, this is why the rotary engine can't pass emission test, there isn't enough time in the exhaust cycle to completely burn the fuel, it cools off to soon after the exhaust port opens.
If the exhaust pipes were short enough or there wasn't a muffler then it would be easy to adjust mixture on our bikes.
from rich to lean it would look like this:
Orange attached(to the pipe end, way rich)
red attached(just rich)
blue attached(best mixture)
blue transparent(going lean)
blue unattached(over lean)
If you ever watch the movie "The Spirit of St. Louis" with Jim Steward there is a scene where they show the engine at nite, note the flame is not attached to the exhaust pipe. That was because he was running the engine over lean for best fuel burn.(least fuel consumption)
At any rate all this boils down to, you won't hurt the engine. The true indicator of what is going on will be the spark plugs, just make sure they are the correct heat range and the correct gap.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
I dug out my old TD pipes and took the heat shields off them. I thought you might like to see a healthy pair of pipes! They have been run to over 6,000rpm on a dyno, to optimise air/fuel ratios, which may help explain their spectacular colour. They have certainly been up to dull red hot, to turn that blue, although I wasn't in the booth while the bike was being run, to see that first hand. 
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