BMW Service Bulletin Archive

cv-carbs-470-282-470

M (0 Customer Service V.GmbH B&S N.J Motorcycl~ R 75/5 Re: Constant Velocity Carburetor Gentlemen: Constant velocity carburetors are more critical and therefore, require that the tuning procedures are precisely followed otherwise irregular idle, poor performance, surging in mid-range and slow return to idle may occur. Tune as follows: 1. Remove and dismantle carburetor. 2. Make certain that the slide pilot sleeve has sufficient clearance in the dome bushing to allow the slide to fall freely of its own weight. The desired clearance is 0.07 mm (-.003 11 ). It is very important to have this clearance. To obtain this, ream the bushing in the cover with an adjustable reamer. Polish the guide bushing and pilot sleeve with crocus cloth. Install the slide dry. 3. In case surging was experienced, raise the slide needle to the third notch from the top by twisting 90ยฐ and pushing it in. Exposed portion of needle b~low slide in third notch from top is 39,5 mm Cl.555″), second notch used to be 41.2 mm (1.622″). 4. Before assembling the carburetors, clean all components. A. Inspect diaphragm for cracks, tighten dome screws slowly alternating in an X pattern and make certain the slide moves very freely when the 4 screws are fully tight. B. Check choke operation, lever has to move freely and close through the internal spring. c. Adjust carburetors to their basic setting. la Back off butterfly adjusting screw urttil it is clear of the operating lever. Tighten screw until ~t just touches the lever and then tiqhten one ful.l_ ~- Ktnntnlsg enomman- Prisc oanalssanc-t Noted- Tomadoa ota – Pr.so conoscanta Ablagt- Archlvff- Flit Atchlvo Betriebsleitung Direction t::\.ono11!~ent WerkJtott Atelier ~~r~1hop KD-Ann1;1hme Rllception clientele Cust. reception “-ยท—โ€ข~- ยท”ยท-โ€ข-1- Werkstatt Atelier Workshop T.ri .. Customer Service V.GmbH/B&S 1 N.J. Motorcycle R 75/5 Group Engine New Jersey,Apr.1970 No. 4/70 (282) – 2 – 2. Carefully tighten mixture screw and then~ 2ff. ~ full turn. D. Move butterfly lever from stop to stop to make sure that it doesn’t bind and that nothtng interferes with its full movement. 5. When installing the carburetor, slot the air intake tubes as shown in the enclosed drawing. De:mrr the inside of the intake tubes on both ends. Coat the inside of both ‘-‘t”‘ds of the tubes with Hylomar. This will prevent any dirt and moisture from enteri~g the intake (available from B & S). 6. Adjust both choke cables to have 0.5 to 1 mm ( .020-.040″) free play. Release the-adjustment on the throttle cables, so they do not interfere during the idle adjustment. 7. Check proper float level with the motorcycle on the center stand and level. A. Pull back wire clip from float bowl. B. Hold float bowl to bottom of carburetor and open petcock. c. Allow float bowl to fLll up. When you are sure that fuel has stoppe” flowing, close petcock and quickly remove float bowl from carburetor. D. Place float bowl on the amount of fuel i middle of bowl from level of the fuel. (.767-.787 11 ) of fuel level surface and measure che bowl. Measure in the ;~ lowest point up to the -. ,re should ยทbe 19. 5-20 mm in the bowl. 8. start motorcycle and le, it warm up. 9. Disconnect right hand 5. ,, rk plug wire. (Install an adaptor into the cap tc r: r:event the cap from being damaged). Adjust butte ! ly stop screw on left cylinder to obtain the slowest r .: sible idle. Correct.mixture K1nntnlsg enommen Prisc onnalssancโ€ข Noted Tomadon ota Presoc onOScenza Ablag, Archives ‘”‘ Botrieb,leitung Werkstatt KD-Annahme Gewtlhrl…Sachb, E-Teildien1t Berriebsleitung Oiredion Atelier Reception clientt!Jle lnspecteur gcirontie Service pikes d6toch6es Werlcstott Monoijement Workshop Cust, reception Direction Atelier Qjroc~16n !._o_l!~~ ~ecep.ci6n i:,l_ient_elo Warranty inspector Spore ports service MoMOQOffl&nl Workshop !nspector garontrc Servicic de reccmbios Direcc16n Ta!ler l ‘ ‘ I v I I / I , t A(chlvo I \ L J ( l Customer Service V.GmbH/B&S, N.J. Motorcycle R 75/5 Group Engine New Jersey,Apr.1970 No. 4/70 (282) – 3 – adjustment to obtain maximum RPM. Readjust butterfly stop screw again for slowest possible idle. Again adjust mixture screw to obtain highest possible RPM. This procedure has to be repeated until the cylinder operates only on the idle fuel system. 10. Repeat the same procedure on the right hand cylinder. 11. Connect both spark plug caps and let engine idle on both cylinders. Reduce the idle speed alternately left and right until the engine idles at 600-800 RPM. This is done by slightly backing off the butterfly screw and correcting the mixture to optimum, as is done in Step 9, only with both cylinders operating. 12. Recheck that both cylinders have the same idle speed, that both die after several strokes, by alternately pulling off the’ spark .plug caps: Theยท final engine idle should be between 600 and 800 RPM. 13. Adjust both throttle cables equally to 0.5 to 1 mm (.020-.040”) free play and make certain that they pull evenly by alternately pulling spark plug caps ,left and right at ~pproximately 4,000 RPM. 14. Do not allow engine to idle for perlonged periods. 15. If a change in operation is noted after a test ride, it is possible that the engine was loaded up during the adjustment procedure, Bayerische Motoren Werke Aktiengesellschaft ยท, I L, J ‘ , r, n ‘ ‘ -./..”–‘-ยท..-_J – Volker Beer .. j: ‘ I ‘ โ€ข i’ ‘ยท, V K1nntnlsg enommen Prisc onnalssanca Noted Tomadon ota Presoc onoscenza Ablage Archives FIieโ€ข Betrieb1leitung Werkstott KD-Annahme Gewahrl.-Sochb, E-T eildienst Betriebsleitung Direction Atelier R6ception clienttle Werkstott Monaqement Workshop lnspecteur gorontie Service pitces d6tocUe1 Direction Atelier Cust. reception Warranty inspector Direccr6n Taller Recepci6n clienlelo Spore ports service MonoQement Workshop Oirezione Officino Inspector gorantla Servido de recombics Direcc16n Toller Recezione clienti lsnellort, nnron7i,i ~,.,v\.,;,.., rirnmh; I”\” … ~ยท~~~ l”‘l

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