Strip, modify and rebuild R1 carburettors
Check the body of the carbs for cracks and repairs around the float bowls and fuel inlet. Operate the butterflies. If they’re seized, spray penetrating fluid around the spindles to free them off.
Use a pair of long-nosed pliers to extract each float. Store in order of fitting. Check the needle valve is still attached to the float when extracting it.
Using a flat-bladed screwdriver, slacken each main jet. They are usually very tight, so be careful not to slip and damage the head.
Use an 8 mm spanner to undo each main jet holder.
Remove the float chamber covers. Each one is fitted with three crosshead screws. Store the covers in order of fitting because they are manufactured to fit accordingly.
Each carb has a small filter that’s secured with a retaining screw. Undo each screw…
Carefully remove each main jet with your fingers and store in order of fitting.
Remove the hinge pin for each float. Use a sewing needle with a bent end to push the hinge pin through, then pull it out with a pair of long-nosed pliers.
…Then extract the filter and store in order. Clean these filters with carb cleaner.
Once each one has been fully undone, extract them with your fingers and store according to the order of fitting.
Extract each diaphragm cover and spring. Store them in the order of fitting.
Use a flat blade screwdriver to remove the pilot/ idler jets. Check they’re not blocked by holding them up to the light. Blow through them if they are blocked.
Carefully extract each diaphragm. Don’t damage the diaphragm. Inspect them for splitting and renew any that are.
We’re ready to rebuild the carbs. Start with the filters from Step 5, the main jet holders from Step 7 and the pilot jets from Step 8. Avoid overtightening any of these parts.
Turn the carbs over. Undo and remove two crosshead screws for each of the four diaphragm covers. Each diaphragm cover is spring loaded, so hold it down when undoing the second crosshead screw.
Wash the carburettors in a degreaser and lightly scrub them with a soft brush to remove any varnish and dirt. Wash with water to remove the degreaser and dry with a heater or hair dryer.
Check the pointed end of each needle valve isn’t blunt. Lower each float and needle valve into position and refit the hinge pins that were removed in Step 3.
Turn the carbs upside down to make sure the floats move freely.
The main jets will need to be enlarged with a drill. Contact Bogg Brothers to find out the recommended diameter of the main jet according to your engine. If you don’t fancy drilling, the same sized main jets from the Weber DGAV can usually be fitted instead.
Check the seal on each float chamber cover is not damaged. Clean it with carb cleaner. Refit them, then turn the carbs over and refit the diaphragms, springs and covers. Avoid over-tightening the retaining screws.
Most bike carbs are secured to the inlet manifold with fluoro-lined silicone hoses (the lining is suitable for petrol). These can be fitted onto the carburettors first and retained with narrow band hose clips.
The carbs and hoses from the last step can now be manoeuvred into position and fitted onto the inlet manifold. Secure them with more narrow band clips. Jubilee clips are not suitable as they will foul the throttle linkage.
Using a flat blade screwdriver, wind in the idle mixture screws, then turn them out three-and-ahalf turns. These may need to be fine tuned when setting up on a rolling road.
Connect the choke and throttle cables, the throttle position sensor (if fitted) and fit an air filter.