Buell XB Tips & Tricks
Replacing intake seals without rotating the engine
My XB had the issue of revs only slowly decreasing when letting off the gas, and sticking at around 2000 RPM. This only happened with the idle speed turned up (my 2007 models has manual idle adjustment) to the recommended setting of 1050 (max is 1150) rpm; with the idle at set around 1000 rpm or lower, revs dropped at a what I assume to be normal speed. I've found multiple causes for the hanging idle issue looking around online:
- The fact that this just happens if the idle speed is set even slightly too high; some recommend dropping it to 950. Which has the added bonus of a cool-sounding lopey idle, but I like to keep as much idle oil pressure as possible. Still, it's a known issue that this happens if the idle speed is set too high.
- TPS reset improperly. I can see it being the cause, though it seems that resetting the TPS is praised as some magical fix-all cure in the Buell community.
- The fact that the ECM is programmed to prevent engine braking by artificially keeping revs up on deceleration. Probably adjustable by remapping, and might tie into the TPS thing. I remember reading a complaint about this in a magazine review of the XB12.
- Leaking intake seals. Sportster/Buell intake seals seem to leak frequently. Thankfully Twin Motorcycles are trying to fix the underlying cause.
- Finally, the engine's got a heavy flywheel so just likes to keep spinning merrily away; don't expect dirt bike like engine braking even on a perfectly tuned bike.
Long story short I had my intake seals checked (spray some carb cleaner on there while idling the engine, check if idle changes) and they were a tad leaky. I ordered some thicker James brand gaskets that have an extra lip under where the manifold touches the intake ports, and went to work. Any serious engine work on an XB requires rotating (i.e. dropping) the engine, something which takes a couple of hours even with experience; obviously I try to avoid having to do so whenever possible. It took a bit of effort but this job is possible with the engine staying put.
The manifold is attached to both cylinders using an allen bolt on the right-hand side and a hex bolt on the left-hand side (hex bolts only on 2008+ models). There's also a smaller bolt attaching it to the bracket which holds the coil (black box spark plug wires attach to).
From left to right:
- American Sportbike intake manifold wrench cut in half; was too long to fit between rear cylinder and frame otherwise. Any 1/4" allen key you're willing to sacrifice will work.
- Torx wrench from bike's toolkit; used to remove airbox.
- 7/16" swivel spanner, used to detach coil bracket from manifold.
- Metal rod used to hammer down on allen key when removing rear cylinder manifold bolt; apparently it used loctite from the factory and was on super tight.
- Screwdriver to pry intake flanges loose.
- Curved 1/2" wrench for intake manifold bolts. This thing is a life saver.
- Allen keys, used to remove throttle housing.
- Hammer, used to beat on metal rod.
- Remove both left and right-side air scoops.
- Remove airbox, air filter, plastic slab below air filter (push breather hoses down through their holes, disconnect sensor cable that attaches underneath)
- It's possible to leave on the velocity stack (rubber tunnel attached to manifold) but it'll be in the way all the time.
- Remove throttle housing from handlebars and detach throttle cables from handle. Now you can detach them from the manifold as well.
- Try and clean away the dirt around the cylinders/manifold as much as possible. I used a flexible vacuum cleaner attachment and rags. Being able to clean everything more easily is a major advantage of actually dropping the engine.
- Remove coil from its brackets, you can leave the spark plug wires in place.
- Remove the bolt attaching the coil bracket to the manifold.
- Remove the bolts attaching the manifold flanges to the cylinders. As described above, to loosen the allen bolt on the right-hand side of the rear cylinder, I had to hammer on it using a rod I inserted from the top of the frame; make sure not to hammer on the injectors or their connectors by accident!
- Once all the bolts are out, the flanges should be slid towards the manifold.
- Finally the manifold can be carefully lifted up and cleaned, and the ports/cylinders can be cleaned as well.
- Clean the flanges and insert the new seals. Coat all interfaces (flange/seal, flange/cylinder, seal/cylinder, seal/manifold) in grease so they seal better.
- Put back the bolts that hold the flanges onto the cylinders, but don't tighten them at all, keep plenty of play so everything can slide around a little.
- Getting the coil bracket bolt back on is extremely fiddly, I managed to so by holding the bolt with one finger from below and one poking down from the top, where the coil is.
- After bolting on the oil bracket, tighten the manifold flange bolts. These aren't supposed to be too tight, they go into the aluminum block after all, so just tighten them nicely but don't force it. Manual says 96-120 in-lbs.
- Put the rest back together...
The manifold being lifted up.
All in all not that hard a job if you know what tools to use, but extremely fiddly. Anyway, after putting everything back together again, the idle speed did drop quicker, but still slow for my tastes with the idle at 1050 RPM. I think I'll keep it at 1000 RPM, which is where it was before changing the gaskets too, though it did drop there slower.
Blocking off evap hose fitting
The throttle body has this fitting for an evap canister hose for California models, see image below. I guess this is supposed to be capped otherwise, but for me it wasn't. This results in unfiltered/unmetered air being allowed into the throttle body. I used a bicycle valve stem cap to seal it, fit perfectly!
Throttle body evap canister nipple.
What I used to block it off.
Preventing the chin fairing from rubbing through the clutch cable
Cut a bit of oil line open and zip-tie it around the clutch line, perhaps after cleaning said line and wrapping on some electrical tape for a snug fit.
I also like using bits of oil line to protect electrical wiring, for example that of the rear cylinder temperature sensor, tends to wear through from resting on the rocker box.