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XB Project

Here is the summary of my 2005 XB12R project. First I would like to say big thx to Juergen Stellmacher and Gernot Matthies from Motorrad Matthies in Tuttlingen, Germany. These guys have been excellent. Juergen runs the workshop and it is a pleasure to work with him. When it comes to taking your bike apart and more importantly getting it back together. The guy is careful, knowledgeable, patient and most importantly meticulous.

The job would have been a lot more difficult without their help. Things can go horribly wrong when you talk to the wrong people and order the wrong parts. I did my homework and spent considerable time on sifting through the net before deciding what I wanted and how to achieve it. The short and narrow is there is no quick fix, for decent improvements you have to spend money, time and be patient (not one of my strong points). The XB requires quite a bit of money when it comes to getting more perfromance from the engie. But I think ist worth.

My intentions were simple, lets have a bit more throttle responsiveness, better sound and as little trouble with "the race commission - the police" as possible. It meant changing the bikes "respiration tract" - heads, air/box, and muffler. When I first got the bits for my bike there was no comparable package available. Now some firms offers a packages that is pretty similar to what I have put together for my bike.

Doing it by yourself I regard as a lot of fun. Planning my project and discussing it with the people who build and refined the parts. Despite all that I bought some parts that in hindsight did not fulfil my expectations. Mostly due to wrong assumptions but in some instances due to real bullshit advice.

"........the world is full of shit and loads of people with big shoffels!"

We started with stripping the bike immediately after it got delievered to the shop and got the engine out. It requires good tools, a well equipped workshop with a hoist, a couple of jacks, girths, the original service manual (most helpful as it lists a couple of tricks) and help from somebody who really knows what he does (a rare commodity in the world of German Buell dealers from what I have been told). I gather you can do it by yourself, but its a bit of an act to get the engine out and the last thing you wanna do is to break bits during this process.

We fitted Stage 2 heads from NHRS. A few words about my decision to go for the NHRS heads. They offered new heads and excellent components within (big vales, titanium valve beds, beehive valve springs etc.) combined with CNC head porting and a track record of many years. The service of Nallin Racing was superb and the heads/valves were adjusted by NHRS to fit with the rest of the engine setup. I dealt with Justin Schilling who was very helpful. You have to tell them your engine specs when you order the parts and it will work very well!. Still check your valve to piston clearance - should be no problem with standard pistons/rods/cams as long as you tell them before!). You need to check the clearance of your rocker boxes. We had to remove a bit of material from the rocker box inside walls to gain at least .020” (0.508 mm) of clearance for each spring. I also recommend the Commetic gasket kit. Read the instructions carefully to avoid mistakes when fitting the gaskets and the heads. There are a number of differences when compared to the standard head fitting instructions. Another very positive experience was the reliability and punctuality of the service and the delivery by Nallin Racing. Only few people in this "Tuning business" seem to have the parts in stock they advertise on their sites. Some of the stuff is also difficult to get anyway or so new that considerable waiting times are not unusual.

To further improve the engines "breathing" we fitted a FAST System. I inserted 3 additional fittings/grommets in the heat blanket (14mm inside diameter) to pass the engine air vents through and fitted two little K&N filters onto the original tubes (by the way, never block these tubes or you can pressurize your motor with potentially nasty results!). I also put the air temperature sensor into one of the additional grommets (it sits now in an almost original position). This way I have a clean setup (the stock rubber velocity stack and the complete inner air box are discarded). I also disposed the exhaust valve motor and fitted the electronic part from SF-bikeparts. Stefan Freitag is another knowledgeable and helpful guy in particular when it comes to XB electronics.

To get more airflow to the rear cylinder and for the looks we fitted right and left side carbon air intakes by Ilmberger (very light and well fitting). Thie has a dramatic effect on the frequency the vent starts. I basically shuts it up for good.

Now it was time to get rid of the ugly stock muffler. We initially fitted a Double VIPER muffler. Right from the beginning I noted that it was a bit to loud for my taste (The man in black/gree or blue with the funny hats also object to these pipes frequently, despite the dB killers). The welding is a rough but it fits resonable well and looks good. HSA has now produced a much better performing exhaust called the Viper Race.

Having read a few things about spark plugs I had bought the Brisk BOR12LGS..............which caused the first problem we encountered. After reassembling the engine we had a few short test runs were the engine ran at low revs and the BOR12LGS sparks promptly clogged up resulting in misfiring. Despite cleaning and drying them.........the engine refused to work with them. We than used the original spark plug’s and the problem was immediately I think that it is probably best to do the first test runs with the original spark plug’s. I contacted Matthias Krist from AMTEC via He suggested to try the BOR14LGS and explained that the BOR12LGS is to "cold" (small heat storage capacity) for the increased filling and is only recommended for stock engines. He felt that a motor like ours would probably need the BOR14LGS. So its probably easier to try the "high tech sparks" a bit later. By the way, with the FAST system it is no problem to change the rear cylinder spark plug quickly after taking the left air intake and the top cover off. I continued with the stock sparks and decided to revisit this problem a bit later.

Finally after 500 Kilometers of careful below 3000 Revs road crusing........time for the ECM training and a first time reality check.

Surprise...............the engine was not revving-up as quickly as the initial experiences during the first 500 had made me think (minimal throttle turning massive push forward in the 1500-3000 range). In fact between 5000-6200 revs it felt like the engine had less performance than the stock bike. Despite this......... The lesson I learned from this experience was simple..........With the high flow heads the Viper Race did not work well and to be fair it was never designed to do decision for buying the Viper Race was based on its looks. In hindsight a silly mistake on my part. A different solution was needed and found quickly............we exchanged it for a Deep Thunder system from Hillbilly. The flip side was we again had to lower the engine to fit the new exhaust pipes.

So here are my first impressions of the deep thunder exhaust system. It replaces everything outside the cylinder outlets (pipes and muffler). Its weight is about half of the Viper Race (due to the Titanium cans). It looks great. But there are massive Problems with ground clearance and it is a real pain to fit the exhaust pipes. The stainless steel pipes have a larger diameter than the stock pipes (50 mm inside diameter).

After fitting the Deep Thunder, we disconnected the battery to erase the ECM data and performed a TPS-zero.

We noted like a lot of people before, that the TPS adjustment is crucial to how the bike will run at low rev and how it will respond to the throttle. It makes a very big difference. I would certainly recommend to do this after any kind of modification affecting the engine.

Again time to train the ECM. (To get the ECM to switch out of the closed loop mode into learn mode, you need to ride within the 3000-5000 rev band. Make sure you always stay 1/4 clear of full throttle. When the throttle is opened quickly and fully the ECM switches the "learn mode" off and there is a time delay until it restarts acquiring data. I did about 60 kilometres of ECM training.............and than the desire to find out if the package would work took over.

Reality check take two..........what a difference. The DeepThunder gives the bike a nice low frequency growl at a very acceptable noise level at street cruising speeds (unfourtunately the mufferls frequently make contact with the road and there are other problems with this exhaust system that make it very irritating to maintain on your bike!). This changes once you start turning that right wrist when the V twin takes a deep breath matched by an intensifying thunder like may wonder how the bike feel now……………well…………..lets call it…………..very agile, massive kick in my butt when I open the throttle...........what joy! Now I have a lot of torque spread over a range of 2500-5500 (I have not pushed above 5500.......for the moment) and it feels that this pretty constant push will lead straight into the rev limiter..........The bike has now a well spread range of usable power, revs up quickly and has a sound that makes people turn their heads because its unusual and not because its shit loud!

Next stages: I like the idea of lightning the primary drive so I build a solution based on the aluminium superlightweight motorsprocket (sporster) and superlightweight clutch basket sporster. This package works very well and is reliable.

I hope that some of you will find this summary helpful. Please note: I am not an engine tuning expert. Nor do I claim to have particular insight in the mysteries of my Buell XB12R. This summary is just a personal log of my experiences. My time is unfortunately very limited, so please forgive when there is a delay in my replies in case you would wish further information. I am sure that the above named people are more than happy to provide assistance as it is there business.

Comment 04/2007: I wrote this at the beginning of 2005 and a lot has happend since......and knowing what I know now a lot of things I would have done differently, but anyway one has to start somewhere.......

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