120 tuning..open loop vs closed loop

[fmj1550]

Im thinking about trying a 2 in 1 exh. ( maybe a boarzilla ) and trying to find somewhere to get a really good tune to gain a little more hp and torque and get rid of the tq dip in the 2000 to 2500 rpm range. I have a SE super tuner. Are there advantages to going with an open loop tune ? To do this would I have to purchase a different tuner ? I am at 119hp and 121 torque now with a dealership tune. Am i wasting my time and money trying to get around 130 tq with no dip ? Thanks for any advice.

[strokerjlk]

That's a great idea.
You can use the tuner you have , and tune it open loop.
Your motor will be much happier.
You should hit 128-130 tq.no problem .
Hp with that cam won't square up with tq. But I think you already knew that.

[aviscomi]

I've been wondering how much power is loss on the 120's running True Duals, 119hp and 121 torque is a noticable amount. Most of us are averaging 130ish while running 2/1 pipes.

[strokerjlk]

He has a short cam and diff heads
My Reinhart t/d's on the crate made 136 tq
They can do better than most 2-1 's on tq.

[aviscomi]

I guess I should have read his sig...

[INDEPENDENT 1]

I never tune closed loop. I wouldn't do that to my worst enemy! If you want to take the drive, I'd be happy to oblige and as already stated, you will most definitely notice a difference in the way it runs. It will be much more responsive. As for exhaust, the pipe you're considering should work well. Another option is the Dragula. It's less costly and I've had good results with them.

[fmj1550]

Thanks for the advice, I will be in pursuit of at least getting an open loop tune. Stroker, yea I know my heads and cams are on the short side for making big hp #'s. I should have went a little more aggresive. You stated that the RH td's make good torque. Do you think I can get 128 to 130 tq with only a tune ? I have also been thinking about bumping my comp up a little and trying the TR662-2 cams.

[INDEPENDENT 1]

I wouldn't get too caught up in chasing a number. Different dyno's show different numbers. The driveabilty and power at partial throttle positions is what makes a bike a good driver unless you are just drag racing. There's a difference in a bike that has been dyno'd and a bike that has been tuned. I'll take a bike that has been TUNED and might show lower peak numbers over a bike that has been dyno'd and has great 100% throttle numbers every day of the week and twice on Sunday. Good TUNERS are hard to find.

[Ziggy57]

Originally Posted by INDEPENDENT 1

I wouldn't get too caught up in chasing a number. Different dyno's show different numbers. The driveabilty and power at partial throttle positions is what makes a bike a good driver unless you are just drag racing. There's a difference in a bike that has been dyno'd and a bike that has been tuned. I'll take a bike that has been TUNED and might show lower peak numbers over a bike that has been dyno'd and has great 100% throttle numbers every day of the week and twice on Sunday. Good TUNERS are hard to find.

Excellent points!

Raw power is fun but driveability is key!
Although my motor made really good numbers in my book, 143hp/140tq, I spoke with Steve(GMR) in detail about my goal to have reliability, driveabilty and to run on pump gas.He spent the better part of 2 days "tuning " my bike. I had one of my previous motors "dyno " tuned years ago at a shop in San Jose, Ca. and as a result it was too lean and lost a piston.

John

[cruzmisl]

Probably a dumb question but can someone explain open vs. closed loop?

[INDEPENDENT 1]

Basically, in closed loop, your EPA compliant O2 sensors are adjusting to make your bike run within the parameters of the EPA regulations creating a lean condition. In open loop, your O2 sensors are not doing that.

[fmj1550]

Great point Independent. Thats what is most important to me...drivability and part throttle response between 2000 and 3500 rpm which is where i am 99 percent of the time. Thats why I was wanting to get rid of the tq dip.

[cruzmisl]

Originally Posted by INDEPENDENT 1

Basically, in closed loop, your EPA compliant O2 sensors are adjusting to make your bike run within the parameters of the EPA regulations creating a lean condition. In open loop, your O2 sensors are not doing that.

So are the o2 sensors being used at all?

[INDEPENDENT 1]

Yes, they fill the bung holes in the exhaust pipe.

[guydoc77]

Originally Posted by INDEPENDENT 1

Yes, they fill the bung holes in the exhaust pipe.

And that's their most important function, at least the NB sensors.