Author Topic: Bren tuning - any up-dates??  (Read 2539 times)

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#10

Offline Mark_62

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Re: Bren tuning - any up-dates??
Reply #10 on: February 01, 2020, 01:30:59 AM
All,

I finally got to the point where I am now considering how to proceed with fuel/ECU changes. I spent a good deal of January with my bike stripped down studying the frame/engine and the over all design. I like what I see so far and was happy with the ease of taking it apart and assembling it. I ended up installing some parts in preparation to my next step, although at this point, I do not really think they contributed much. In fact the one thing to me that turned out to be exactly as advertised was the Akro front header. They claimed an approximate 6 hp increase in the mid range, and a peak hp of 2-3 at redline. I think it got real close.

The header made the low end much richer almost to the 4K mark. The added midrange is noticeable and based on the A/F reading from the dyno, this bike could be ridden with no additional changes if elected to do so. Note on the spreadsheet that (1) was our original run on 11-11-19 and the (2) was from 01-30-20. Our printer bit the dust and we were not able to put together everything I wanted, I will revisit that part.

Heading to Chicago next weekend for a bike show. I hope to see Bren there but have not checked the line up yet. I am at the point where I want to know specific details about the ECU and exactly what restrictions exist, and what restrictions will be removed as part of their service. I will post results if or when I decide and implement the next phase  on this project. 

Cheers!

Mark62



"Life is fast, never look back and never let off"

#11

Offline SimonS1KR

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Re: Bren tuning - any up-dates??
Reply #11 on: February 01, 2020, 09:22:33 AM
Mark, Iím really enjoying your methodical approach to quantifying performance gains. This kind of information is sorely lacking.

Iíd be really interested to know how the gains youíre seeing translate to the real world. Is your bike now better to ride in some way, either the feel of the experience or in measurable performance terms?

From a measurable point of view, what would really interest me are comparative in-gear acceleration times (30 to 70 mph in 2nd, 3rd and 4th gear etc). I donít find 0 to 60 mph or standing 1/4 mile times all that relevant to the real world as few of us spend our time drag racing from every set of traffic lights.

#12

Offline Mark_62

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Re: Bren tuning - any up-dates??
Reply #12 on: February 01, 2020, 01:32:34 PM
SimonS1KR,

Thanks, I try to evaluate my changes as accurately as I can, and where possible I used fixed methods to do so. I have a bit of an engineering mind, so this is a big part of what I enjoy through motorcycles. Of course riding the bike plays a huge role, and that is why I insist on quality functionality when it comes to making changes.

Measuring changes: this in itself is something that must be done with care. I do not have a way at this time to accurately measure (in time increments) roll on acceleration from 3rd, 4th and so on. But what I do is use a drowne bike as a standard and make comparisons in such gears at various speeds. This is pretty effective but again, no real numbers to accompany the process. Currently I use a VFR1200 and a BMW1300 to make the comparisons. If the weather is decent, that should happen this weekend. I use scales to document weight on given parts as well as the bike itself. Example; my bike stock with gas running out of the overflow was 458 pounds, the header exchange including the servo removal was a 12 LBS 8 ounce loss. Rear sprocket 1.1 pounds and so forth. I use a dyno to measure HP & torque, but insist on using the same machine and operator. I do not consider myself a drag racer, but occasionally I visit the track to measure acceleration. It is a consistent way to measure not only elapsed time, but equally important terminal speed. I also measure top speed but only calculated by tachometer readings. They are more accurate than speedometers. And last, the one that no one cares about, gas mileage. This is important to me as well. This bike makes that easy because of the average speed feature.

The gearing change was a good example to me. By reducing the rear sprocket from 45 to 43 teeth I got the following results; 7 hundredths of a second quicker acceleration and two miles per hour faster terminal speed, almost 6 miles per hour faster top speed, and 1.7 to 2 miles per gallon better mileage. It did loose a slight bit in roll on comparisons, but the trade off was more than worth it IMO. Also, the bike is more pleasant to ride with the lower rpms (there's that quality functionality part).

My Buddy John calls this a "sickness that you never get over". He may be right, I have been sick since age 8!  :008: :008: :087: :087: :112: :112:

It is just mid winter in Kentucky and so there is more study research and hopefully development in the coming weeks. IMO, BMW did a great job with this bike. I have really enjoyed every aspect of it up till now.

"Forever the student"

Mark62 - 2020

 

"Life is fast, never look back and never let off"

#13

Offline S1000R_QC

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Re: Bren tuning - any up-dates??
Reply #13 on: February 14, 2020, 02:23:21 AM
Hi, here's are my results of the brentuning stage 3 flash



Both run were made the same day on the same dyno. Stock tune vs stage 3.

Here's my mod

Hindle full exhaust system
Iat relocation
Sprint air filter





#14

Offline Mark_62

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Re: Bren tuning - any up-dates??
Reply #14 on: February 14, 2020, 01:49:26 PM
S1000R_QC,

I did see your post earlier, and to me it is very impressive. Also kudos for spending the extra time & $'s to dyno the bike before and after. I am a bit old fashion in the sense that I like measured results (no matter which way they turn out). Other wise, we cannot learn over the long run. Your post not only validates your project, but others on here as well that used Bren. I also am considering the Bren tune to finish my bike for the 2020 season. There is another gentleman on here that is going forward with the RR cam installation. I look forward to those results. I hope he take the time to do what you did with dyno testing before and after.

I do plan to visit a couple of events this year for some quarter mile and top speed testing if all goes well. I will share those results when available. But it's been a tough Jan/Feb so far with other challenges here, so we'll see how it goes?

Meanwhile, keep up the good reporting and thanks again!

Mark62

"Life is fast, never look back and never let off"

#15

Offline podders

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Re: Bren tuning - any up-dates??
Reply #15 on: February 14, 2020, 05:07:02 PM
Nothing to add other than 10/10 for the lovely old CBX and its location.... :821:

#16

Offline SimonS1KR

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Re: Bren tuning - any up-dates??
Reply #16 on: February 14, 2020, 05:15:56 PM
I really hope at least some (if not all) of the photos that Mark posts are from his personal collection... because that would be one hell of a biking history!

#17

Offline Mark_62

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Re: Bren tuning - any up-dates??
Reply #17 on: February 14, 2020, 05:22:28 PM
Thanks podders!!

I figured not too many would recognize it on here. It was one of my favorite bikes from the seventies. It had many firsts still found on modern bikes today. And I have dubbed it one of Japan's first retro bikes if you know anything about Mike Hail or the 1960's when the bike actually competed.

This one belongs to my Buddy, it's the last one he had. It's actually on the second floor of his garage, along with a few others.

Cheers!

Mark62

"Life is fast, never look back and never let off"

#18

Offline SimonS1KR

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Re: Bren tuning - any up-dates??
Reply #18 on: February 14, 2020, 05:56:25 PM
There are some great vids on YouTube showing just how awesome the CBX sounds when used in anger  :005:

#19

Offline Mark_62

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Re: Bren tuning - any up-dates??
Reply #19 on: February 15, 2020, 12:51:56 PM
SimonS1KR,

I wish I could lay claim to having all the bikes I have pictures of but.... unfortunately, not so. Although with a stay at home wife and four children, I feel very lucky to have what I do (or did). In the case of my 1979 CBX I owned for a few years, I let it go to buy my first house in 1983. I hated to loose it but felt the sacrifice was worth the trade at the time. But I really loved that bike and still hold it as one of the best bikes I owned for it's unique character, good performance, striking looks and sound. And oh, that sound... different than anything on the road then or now. I had a grand prix kit on it, a D&D exhaust, ported heads, re-degreed cams, alloy sprocket, and I drilled the disks. The bike was a pure joy everytime out. Here is a crappy picture of it.   

"Life is fast, never look back and never let off"

 



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