Flashed CB1100 Review

[CIP57_imp]

80 hp at the rear wheel not to bad
CIP Don says your taking your bike to him! Today? Tomorrow ? Let us know the results!!

I was going tomorrow but had to cancel due to work issue's. I have to re-schedule.

[Bike #12_imp]

Why do the engine revolutions drop off so suddenly at ~6900 rpms? Seems like horsepower production is still climbing.

[DAC]

Wow. Torque curve about as flat as you could ever expect.

Bike #12 - That may be where the ecu rev limiter kicks in. Others please check in to confirm.

[grover_imp]

Wow. Torque curve about as flat as you could ever expect.

Bike #12 - That may be where the ecu rev limiter kicks in. Others please check in to confirm.

The stock rev limiter must be at least 8500-9000, he's probably hitting the top speed limiter of ~115 mph in 3rd or 4th?


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[DAC]

Ya. That's what I meant - just didn't say it right.

[Greg_imp]

Bike #12

The dyno operator wondered the same thing. I had forgotten to tell him about the rear wheel top speed limit at around 112 mph. If he had done the WOT run in 5th gear, the cutoff would have happened at a lower RPM, which makes me wonder just now if 3rd gear is actually a better choice for doing the WOT run on a stock CB1100. I mean "better" in that the bike will rev higher and show higher peak HP. Anecdotal evidence suggests RPM limit is not reached in 3rd gear before the speed limiter kicks in. Which would further suggest that RPM limits are redundant in all except 1st and 2nd gears, but that's just dumb speculation.

Speed and RPM limits have been debated at length ever since the CB1100 was released in the US. The posts make for interesting reading if you care to drill down on it.

[Greg_imp]

Here is are dyno charts from a stock CB1100, mileage 3400. There are 3 runs: 1/4 throttle, 1/2 throttle and wide open throttle (WOT). I believe he had it in 4th gear for the WOT run.

He also did an idle chart that is not shown here. The AFR was in the range of 17:1

They do run lean out of the box!!

For those who are following along merely out of curiosity, CIP is referring to the bottom section of the graphs labeled "Air/Fuel Ratio". Lower numbers are richer, higher numbers are leaner. The red dotted line at 13 is roughly the ideal air/fuel ratio for a happy engine; 13 parts of air to 1 part of fuel, written 13:1.

So-called perfect combustion, where all the air and all the fuel is consumed, occurs at 14.7:1. Emission standards require that air/fuel ratios be at least 14.7:1 for almost all of the time the engine is running, and the CB1100 only dips below that at wide open throttle and near the top of the RPM range. Practically speaking, most owners will rarely or never operate in that range, so their bikes are running lean all of the time.

One of the great things about our bikes is that they are engineered to be smooth, powerful (enough for most), quiet, relatively clean running and fuel efficient all at the same time. Since optimum tuning for any one of those variables compromises the others, the designers have done a great job of balancing contradictory parameters and making it all invisible to us.
Somewhat related to CIP's thread is air intake.

I calculate the air inflow at 7k RPM at around 141 cubic feet per minute. To feel what this is like, turn on your shop vac and hold your hand near the open hose. A typical large shop vac pulls in about the same amount of air and the vac's hose is about the same diameter as the inside of the air filter on your bike.

[flynrider]

Bike #12

The dyno operator wondered the same thing. I had forgotten to tell him about the rear wheel top speed limit at around 112 mph. If he had done the WOT run in 5th gear, the cutoff would have happened at a lower RPM, which makes me wonder just now if 3rd gear is actually a better choice for doing the WOT run on a stock CB1100. I mean "better" in that the bike will rev higher and show higher peak HP. Anecdotal evidence suggests RPM limit is not reached in 3rd gear before the speed limiter kicks in. Which would further suggest that RPM limits are redundant in all except 1st and 2nd gears, but that's just dumb speculation.

Speed and RPM limits have been debated at length ever since the CB1100 was released in the US. The posts make for interesting reading if you care to drill down on it.

Third gear is the best choice for a dyno run on a speed limited CB11. Others have posted their charts and it is possible to hit redline in 3rd just before hitting the speed limiter. If your run had been done in 3rd, I'd expect that you would have seen a few more HP, as the peak HP on runs in 3rd gear has been shown to be around 7300-7400 rpm. You didn't quite get there.

From a performance point of view you should make dyno runs in the gear that comes closest to a 1 : 1 ratio. That minimizes gear reduction losses in the transmission. On the CB11, that would be 5th gear. Unfortunately, with the limiter in place, we have to be content with the highest gear that will allow a full run to redline.

I agree that the rev limiter is pretty much only useful in 1st and 2nd gear. In 3rd, you'll be reaching the rev limit and the speed limit at about the same time.

[Ridem32_imp]

CIP will be able to tell us lots in a few days when dyno his bike with the flash ECM Don will fine tune it and will know what the motor can really do! It's not honda,s idea to really power back the motor it just has to meet all the government rules and EPA. I think a lot of us will be shocked to see what a cb11 motor can really do. Time will tell

[Greg_imp]

CIP will be able to tell us lots in a few days when dyno his bike with the flash ECM Don will fine tune it and will know what the motor can really do! It's not honda,s idea to really power back the motor it just has to meet all the government rules and EPA. I think a lot of us will be shocked to see what a cb11 motor can really do. Time will tell

I agree, but dramatically increasing power creates other issues. Many high powered bikes have traction control as part of their throttle by wire design. CB1100 has a mechanical throttle control so there's no possibility of mediating lots of power when conditions warrant it.