Is this dyno graph consistent with a de-cat, or is there air ingress ?

chrismckay

Registered User
#1
Hello Guys,

I want to ask your opinion on the following

I had a custom map made for the motorcycle at "Dyno Centre A" with the bike having the following mods....K+N filter and Dam exhaust.

At a later date I had another map made at "Dyno Centre B" with the bike having the following mods.............K+N filter and Dam exhaust (baffle removed), catylytic converter removed


"Dyno Centre B" carried out a base run using "Dyno Centr A's" map, with the additional modifications of baffle and cat removed He said that the fueling was way way lean, he even swapped out his O2 sensor to satisfy himself that his equipment was working, the second O2 sensor yielded the same results. He then asked me if I was certain that I had blocked off the pair valve, as he was surprised at the AFR readings. I confirmed that I had . So he proceeded to start tuning the motorcycle with the latest dynojet software, this was basically a programme where you enter the desired AFR values in the cells and then hold the throttle open at the desired percentage and the software produces a trim table which is then transfered to the power commander. job done and AFR looks pretty good on the graph.

I have not had much ride time since the re-map due to being offshore. However I have been thinking a lot about "Dyno Centre B's" concern about the lean mix and this got me thinking about if there could be any other air leak paths in the exhaust system causing the base run to run to show such a lean reading (bearing in mind baffle and cat are now removed).

Playing on my mind is the following....I remember when removing the headers from the engine, I had left the two short sections of pipe from the rear cylinders attached and disconnected the rest of the rear exhaust from the sleeve that connects the two. When fitting the de-catted exhaust ( all new gaskets apart from the short pipework from the rear cylinders which were not removed) I had a bit of a struggle getting it back on, I loosely connected the front headers then tried to get the rear pipes married up at the sleeve joint, this took a bit of wiggling of the short sections that was left attached to the rear cylinders in an effort to get the system to marry back together. this has left me with the niggling thought in my head that in "wiggling" the rear short pipes that i might have disturbed the gaskets attaching them to the engine, thus introducing air into the exhaust system that may have gave a bogus reading whilst the bike was on the dyno getting the map made.

From looking at the AFR readings on the charts do you think that the de-cat and removal of the baffle could cause such a difference in the fuel mix.....or do you think that there would be the possibility of a gasket passing introducing air, due to me having a struggle fitting the exhaust back in place?......

As the gasket that is sealing the rear cylinders is not really easy to get at, is there a tell tale or easy way that I could check????

Below is the dyno chart from "Dyno Centre B" with the baseline in blue and the new in red


HMD dyno.jpg
 

PeteD

Registered User
#2
Not sure if it helps but whilst going from basic to full exhaust change I had a period when I removed the exhaust except rear header pipes. I removed the cat fitted K&N filter and Scorpion end can. I believe I ended up with an exhaust leak where the exhaust fitted onto the rear headers. There are two doughnut shaped ring gaskets made out of what I would describe as a sort of brillo pad. The problem I had seemed to be coming from there. When I had an exhaust made for the bike the other week the rear header pipes were not touched and just a normal connection without the brillo gaskets was fabricated and fitted. No more problems!! My exhaust leak never showed up on the dyno graph like yours though. I had a dip in midrange power which manifested itself as a sort of stutter between 3 - 4K revs. This has since gone and bike pulls like a train throughout the rev range. I would though, point out that I have not got Power Commander system. I went down the route of a ECU re-map by Geoff at Hilltop Motorcycles in Hinkley. His system uses the two O2 sensors for A/F monitoring/changing and works the very best. Good luck in your modifications.
 

chrismckay

Registered User
#3
Hello Pete,

Those gaskets that you talk about being like a brillo, I actually replaced those with new ones and it was them that made the job of marrying up the exhaust to the rear cylinder headers a bit of a challenge.
I ended up giving the rear header pipes a bit of a jiggle to get everything lined up and it was because of this that i have a niggle that I might have upset the copper gasket at the exhaust port
I may be worrying over nothing as from the chart where he has tuned the AFR to 13.1ish there is an increase in both HP and torque.

Did you have a complete set of headers manafactured?
 

PeteD

Registered User
#4
Hello Pete,

Those gaskets that you talk about being like a brillo, I actually replaced those with new ones and it was them that made the job of marrying up the exhaust to the rear cylinder headers a bit of a challenge.
I ended up giving the rear header pipes a bit of a jiggle to get everything lined up and it was because of this that i have a niggle that I might have upset the copper gasket at the exhaust port
I may be worrying over nothing as from the chart where he has tuned the AFR to 13.1ish there is an increase in both HP and torque.

Did you have a complete set of headers manafactured?
Hi Chris. I had a complete exhaust made with the exception of the rear header pipes. They were too labour intensive to bother with. I have not experienced any bother from them. I replaced the nuts, studs and gaskets for the front down pipes. I now have a four into one exhaust. I willl attach some photos. IMG_666A0EC6974B-1.jpeg IMG_0404 3.JPG IMG_7120.JPG IMG_9533.JPG UNADJUSTEDNONRAW_thumb_9ad.jpg
 

Pig949

Registered User
#6
Hey Chris

Your new red line looks good, with the AFR fine from 4K onwards. This is my before and after at Hilltop. The bike is standard apart from an Akra end-can minus baffle. it was done in July when it was nice and warm, note 24 degrees at 10am.

Stu

IMG_5897.jpg
 

Pig949

Registered User
#9
The power and torque fall off a cliff because this was a 6th gear run and the speed limiter stops the fun at 157mph - circa 8,700 rpm

So a couple of weeks later I went to a local dyno, on a proper hot afternoon, for a run in 4th gear to th
 

Mr.hifi

Registered User
#12
Hi 949, so after the hilltop ecu reflash the speed limiter isn't gone ????
I live in Denmark and are considering the hilltop reflash....but i thought the 1-2-6 gear limiter was gone with hilltops reflash...
Best regards from Denmark IMG_20180731_130324932.jpg
 

Pig949

Registered User
#13
No, the restrictions in 1st and 2nd, together with the speed limiter are unaffected, the Hilltop software just works with fuel and ignition timing. However the bike is substantially nicer to ride at lower speeds and pulls brilliantly. I do have a harshness between 4 and 5k which is not ideal, particularly in top gear, but I can now ride at a constant speed much easier rather than having to be either accelerating or decelerating.
 

PeteD

Registered User
#14
No, the restrictions in 1st and 2nd, together with the speed limiter are unaffected, the Hilltop software just works with fuel and ignition timing. However the bike is substantially nicer to ride at lower speeds and pulls brilliantly. I do have a harshness between 4 and 5k which is not ideal, particularly in top gear, but I can now ride at a constant speed much easier rather than having to be either accelerating or decelerating.
When I had my ECU mapped by Geoff he told me that the restrictions in first and second gear were not removed altogether as Honda had put them there for a reason but the limiter had gone. I asked him specifically about that because I saw 170mph on the readout when he mapped mine. I seem to remember him telling me that he shut off at about 8800rpm because it had made full power and anything further was just noise.
 

Pig949

Registered User
#15
Hey Pete

Peak power for the standard engine is at circa 10k and we haven't changed the architecture of the engine (by that I mean cams etc), so I would expect your engine to peak at about the same revs. I would be tempted to have a baseline run at a local dyno in 4th gear, particularly with that gorgeous new exhaust of yours! It cost me £50 and was well worth it for the excitement :)

Stu
 

Mr.hifi

Registered User
#16
No, the restrictions in 1st and 2nd, together with the speed limiter are unaffected, the Hilltop software just works with fuel and ignition timing. However the bike is substantially nicer to ride at lower speeds and pulls brilliantly. I do have a harshness between 4 and 5k which is not ideal, particularly in top gear, but I can now ride at a constant speed much easier rather than having to be either accelerating or decelerating.
949, so the hilltop/ECU remap and the Akra end-can minus baffle increased bhp at the wheel with about 16 bhp ? Everything else on the engine are standard ?
Kind regards from Denmark
 

Attachments

Pig949

Registered User
#17
Yes, everything else standard, in fact when I changed the air filter a few weeks later it was filthy, I wouldn’t be surprised if it was the original !
 

Mr.hifi

Registered User
#18
How funny you mentioned the air filter!!! I bought my VFR in july-18..32000 km...1 week ago the air filter and the spark plugs was changed....my missile are visually mint condition, but somebody forgot the maintanaince...never seen such a dirty filter before....the spark plugs was also the originals...34500 km.. anyway after 2500 km this summer, No oil or water consumption.. IMG_20181112_173858051.jpg
 
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