Scrambler 800 Track Bike Tuning

[koko64]

Edit.
Second dyno session completed. I had a closer look at the dyno chart. Gained another 2-4 hp right through the range after tuning the front cylinder. The dyno operator said the difference in mapping required was substantial. 5 ft/lbs of torque gained at 3000 rpm. About 3 more peak hp but good gains in torque and hp through the whole rev range. An increase in response and smoothness was reported by the owner during ride testing.The gains match those from similar intake, exhaust and tuning mods achieved by others locally. It highlights the severe restriction of the oem airbox design compared to say an 800 Monster. About 12 peak hp was gained, or rather to be more accurate, 12 hp was recovered! This also highlights the value of individual cylinder tuning on a V/L twin.

Common map vs individual cylinder mapping. From my page.

https://www.facebook.com/photo.php/?photo_id=887711399817468


Local shop results to indicate before and after from stock vs the mods mentioned. Link provided to comply with copyright. Looks like a Termignoni high rise full system and they dyno tune/flash the ECU. Kudos to them. From their site. A good reference and about the same result. Brad bikeboy uses these guys so thats a strong recommendation.


https://dynobike.com.au/product/ducati-scrambler-800-stage-2-custom-tune-15/

[koko64]

In regards to exhaust, the Delkevic conventional 2-1 with 450mm oval muffler was used. Note that the Delkevic site indicates more lower and mid range power with the shorter mufflers in their range while using the same mid pipe. This indicates the influence of total pipe length. The effect was more pronounced the shorter the muffler. 350mm and 225mm length mufflers were available.
The shortest Delkevic muffler matched the gains of the Termignoni and Zard  2-1 full systems when compared to their respective company dyno charts.

[MonsterHPD]

Hello,
don't know if you also read other forums; there's quite an interesting thread there concerning exhausts:

https://www.ducati.ms/threads/exhaust-design-question.751516/#replies

It's well worth the effort to go through!

[koko64]

Good article.
I thought of doing a 2-1-2 ala Ducati M900 style with two of the Delkevic pipes, but a short and annoyingly loud 225mm Delkevic muffler would achieve the same goal within a pony or two. The Zard short muffler may have given more mid range but the owner couldn't stand the noise. Reducing overall length of the system by 200-300mm should help the midrange from what I've seen of dyno charts.

[koko64]

We are going to try another exhaust on this bike seeking more power through the rev range. Various dyno tests supplied by different exhaust manufacturers seem to indicate that the current exhaust is too long by approximately 225-300mm depending on pipe diameter. The pipe to be tested will probably not make more peak hp, but my enquiries appear to support a shorter total exhaust length giving 2-4 more hp throughout the bottom end and mid range. My local dyno guy has had this view from the beginning, so we'll see if he's correct. The decible level reported by the manufacturer is moderate for a perforated core, straight baffle type muffler with claims of a deep note rather than a high frequency raspy sound.
I'll update when we try it.

[koko64]

Tested a short loud muffler (Verex) with an instant gain in midrange response reported by the rider under acceleration. Unfortunately the angle of the pipe sent the resonance right into the right ear of the rider. He went back to the pipe that left the noise behind him, so we didn't get back to the dyno. There is a full header set available that routes like an early Monster 2 into 1 system that will have shorter overall length (and not shroud the cambelts). I can't recall who makes it, maybe Spark or some such. I still think a Monster 800 set of headers with twin mufflers modified to fit is the best option.

[koko64]

Further track testing revealed a flat spot and hesitation on the transition from closed to open loop operation. This is in an awkward part of the mapping that causes throttle lag exiting some corners. It did not show itself to the dyno operator but did reveal itself on track in certain corners.
I also tested some O2 Eliminators from Smartmoto with the same issue arising. Interesting.
To my knowledge ,there is no O2 Optimiser specifically made for the SC800 and I used one from an M1100. It gave a 13.2:1 afr rather than a 13.6:1 afr, but the problem was more about device interface then a few points of fuel . Removing it solved the issue while losing a little part throttle low rpm smoothness and torque, but the throttle lag is gone. The motor now storms through the region into open loop/PCVI mapping. This picked up mid range torque and acceleration. It shows the dyno doesn't tell the whole story.

I read some articles on the subject of closed loop/open loop transitions which confirmed my suspicions. The 1100 O2 Optimiser will be saved for an 1100 project.

I note that Kamna did not use a closed loop device, just a PCV.

[greenmonster]