Tuning 40mm BING CV carburetors for BMW motorcycles by ear. I have tried to do it for the carb novice. The BING manual. Bing Carburetor Bombardier Rotax has recently published an updated Bing Jet Chart and Main Jet conversion chart. All ultralights and light planes using ROTAX engines.
Steve Doyle has put together this great and simple guide to tuning your Bing carbs. No need for expensive tuning equipment. So over to Steve.
Any feed back on this How To please email me and I will pass it onto Steve. There are 3 common methods to syncing the carbs. They will all work 1. Shorting the plugs. Using a manometer of some sort.
Carbtune, Twinmax or home made 3. Using your ears. No comprehensive articles that I could find. In the spirit of learning to service and tune at home and after lots of reading, I decided that for me the 'by ear' technique might be the most useful, as it doesn't require any special tools and can be performed anywhere. There is no risk of electrical damage to the bike or the one doing the adjusting. It was very difficult to find a comprehensive description of the procedure, so using the combined knowledge and input of many at boxerworks.com, other internet articles, the 3 usual BMW tech manuals and the BING manual, I have put this together.
I have tried to do it for the carb novice.someone in an early learning phase of carb maintenance, eg me. I have used the 40mm carb 'cause that's what I have, but the principles are transferable to other cv carbs. Starting notes. Minimum 15 minute ride. If not done, you will be left with a high idle once the bike warms up. *This procedure is done with known good valve and timing settings, and a clean air filter. Ensure no air leaks around the carb connections or at the inlet stub on the cylinder.
*Throttle cables must have free play 2-3 mms. You should be able to slide the throttle cable outer (at carb) up and down in the cable adjuster 2-3mm. *The jets/carb orifices, manifolds, seals etc are all clean, tight and not leaking. *All adjustments must be done on the centre stand.
Don’t use the side-stand at all. You will need a working pair of ears, a flat end screwdriver, a 10 mm open end spanner and a fan for engine cooling.
Do not let the bike overheat. A second person can hold the throttle open at 1500rpm, or use a throttle stop of some sort. *When assessing equilibrium between the left and right, place your head between the exhaust outlets and listen for synchrony.
Don’t stay there too long as exhaust fumes aren't useful to you. The orange highlights are the basic setting adjustments. Novation V Station 1.7 Keygen.
Tuning involves ensuring the effect on the engine is equal, and smooth. Everything else is supportive information. Singer Quantum Futura Ce 200 Software more. To simplify the procedure, break down the whole procedure into 3 smaller procedures, doing them one at a time. You must adjust and set- 1.
Idle mixture. Filemaker Pro 10 Bible Torrent here. Cables in synchrony above idle. Idle speed adjustment.
Look down onto the top of the carbs. The throttle adjuster is the straight screw head between the carb and head, which sits above the throttle arm.
The arm has the throttle cable attached to it. Your aim is to set the butterflies to open simultaneously. If you are rebuilding or are just about to mount your carbs onto your bike, these settings can be visualized and adjusted easily before mounting. Otherwise, do them once mounted. On both carbs, if they're mounted, you can use a thin piece of paper between the throttle adjuster screw and where the screw touches the throttle lever. Set equal opening of the butterflies here. Tighten / loosen the screw until it just grabs the paper.
1/2 to 1 turn tighter (clockwise) is about idle speed. That’s where you start to play with a screwdriver and your ears. The idle mixture screw is under the carburetor. Set both carb mixture screws equally, by clockwise rotation in all the way (the leanest), then back out counter-clockwise by 1.25 turns. ***These settings provide the baseline, so if you haven’t already done the 15 minute warm-up ride, now’s the time.
It should run, unless there are other problems like blocked jets/orifices, inappropriate float levels, enrichener circuit is bad. If you plan to further adjust back in the shed, then it’s important to have a decent fan set up ready to switch on once you have parked the bike. The aim of the fan is to prevent overheating. The adjustments should not take more than 6-7 minutes without a cool down ride. Alternatively, go for a ride, take a screwdriver and a 10mm open end spanner, and plan a few stops on level ground to tinker. Leave your earplugs at home. Making adjustments.
For post 1980 bikes aim for 1100 rpm, and 1000 pre 1980. When one carb starts to dominate, that side muffler will start to 'pop' more than the other side. Using the throttle adjuster adjust the other side up to match, or back down the 'popping' side.