| Author | Message | ||
     Squishy |
I know XB12 headers are a bigger diameter than the 9 headers, but will this negatively effect my bike? | ||
| Blake |
Most likely absent any other compensating measures, it will. The larger headers will throw of the entire exhaust tract tuning. How much is hard to say. | ||
| Jadow |
Come on XB owners! Squishy and I can not be the only XB9 owners that have thought about this exchange. In fact when asking NHRS builders what pipe to use they highly suggest an aftermarket Exhaust system that has larger header diameter for performance packages. So spill the Knowledge...who has instaled the XB12 header pipe on the 984 and lived to tell about it? Anyone brave enough to share Dyno results? | ||
| Bombardier |
What about the reverse? 9 headers on a 12. | ||
| Jadow |
Yeah why not? Both bikes have the same Exh. valve size..same header primary length, dumping into a large Muffler. Different stroke so different volume of burnt gases trying to get out, but a smaller dia. pipe could rush things along. What is up Buell? any other manufacture would see the savings using the same pipe on both bikes..using the exh. valve in the muffler to adjust for different volumes and power curves. | ||
| Pontlee77 |
Why do 2008 have thiner pipes? | ||
| Bombardier |
A little more torque as well. | ||
| Buelltuner |
Jadow... smaller dia headers do cause more velocity, but too much velocity causes friction on the inside of the pipe having an adverse effect and actually slowing the gases down. ideally exhaust gases should travel 280-300 ft/sec, increases in tube dia slow the speed, and decreases in dia promote higher speeds. the larger the displacement, the more gases that need to be moved, this why the two are different dia. But as any exhaust builder will tell you there is waaaay more to it than that. | ||
| Thespive |
I want to put 12 headers and a 12 pipe on my 9, while running the Race ECM. Any thoughts? The goal is to have a freer-flowing exhaust to take advantage of the Race ECM without having the noise associated with an aftermarket pipe. Thoughts? --Sean | ||
| Chelpdogg |
I say do it. i dunno what the pipe diameter sizes are but engine is about 20% different. do the math the 984 revs higher than 1203. multipy that by redline and see if they are close. may lose bottom end but gain top end. look at the size differences they do on cars. eg WRX. 2 1/4" pipe is 3.94" standard and 3" pipe is 7" in cross section area. thats about 44% more flow. a huge difference. and every high tech turbo car out there has it done without problems. how many harley's are there out there without any muffler and very little flow restriction and back preasure. . . . | ||
| Jfkersh |
I read Eric rides an XB9 with XB12 headers and throttle body. So if you are looking for answers?? | ||
| Jadow |
I have been living with 12 header with custome mufflers. definitely lost low end and it took alot of tuning at cruze. But the rush at the top is great. I also noticed Twin Motorcycles exhaust system for XR1200 uses the XB9 dia. for the header flowing into a XB12 pipe into a great muffler. So the smaller pipe and higher velocity is correct. I think a correctly made step pipe would work. | ||
| Jfkersh |
I have an XB9R 2003, I have tried TiForce exhaust with almost no packing in the can. It was loud and pretty poor down low. It was better with an XB12 throttle body, but the power up top was awesome. This system came with reducers in the pipe just before the collector, I did not have these in place, the previous owner had the removed. These would be better for low torque I would believe. The bike has the other mods too, white wire, air filter, racing spark plugs a stock ecu that was re flashed to race. I found the race settings were making the bike difficult to ride on the road. So I took the fuel maps and transferred them to a standard ecu. The best improvement I found was the later model XB12 throttle body. The bike was almost impossible to run at 3000 properly. Now I am running the std drummer that has been hollowed out with a half baffle plate and XB12 headers. I will need to map the top end a bit, seems a bit rich, but I have plenty of older maps to choose from, or it will be seat of the pants. |
