Ural (Урал) - Dnepr (Днепр) Russian Motorcycle Carburetors
Contents
1. K 68 to CVK32 Keihin Carburetor Transition http www cossackmotorcycles com dnepr html K 68 Runs a Little Rich Most of the Time Requires Frequent Adjustment to Stay Perfectly in Tune Looks Similar to the K 68 Fitted to Late 650cc Urals They re Not the Same Don t go Swapping Them from One to Another o6 Ural Changed to Dual Keihin Seiki for US Import Models ll Fitted to Pass Stringent Emission Regulations EPA f Current Carburetors for 650 750cc Motorcycles p Generally a Good Carb but Needs Re Jetting to Avoid 3 Overheating at High Engine Loads Must Be Kept Clean and Jets Need Regular Blowing Out Especially the Ones that Can Be Seen in the Carb Throat when Air Filter Pipes Are Removed The common carburetors found on 750cc Ural motorbikes were the K 68 s Prompted by the need to meet the stringent EPA requirements for imports to the US Ural chose the Mikuni which was later replaced by the CVK32 Keihin which appeared in 2000 and has remained steady today Russian Carburetor Time Line 042011 1940 LE 7 E PETI 1 4 E n 1 0 r F N 7 x TN Ww p Ne Ja 1 2 E q hi at N UU C x 7 NM 1 al VY 1 f pu e V4 ASQ 1 37 HON NS eN Chae Paz 0 d CN 5 5 m S gt ba K 302 Y K 63 K 65 K 68 Last of the Dneprs 1975 1980 1985 1990 1995 2000 2005 2010 T2. e Xod DOCVJGHpyeMVoco GHHIHOM UIUECHHG CMECH Pay attention to the opening of the idle channel when operating a motorcycle with a faulty engine Part of the holes could be clogged with soot emissions from the cylinder Coasting Enrichener oppozit ru Slide Diaphragm T oui PRR bt OCHOGHORN NICIONKH Cap ES Tuodpacwa 1 eR Cab ulus S rin Sea 3 7 der if H FUCHOHKIE pies di d jf Y By 7 Slide Spring ayal Seco P E AHH MOIH GHA HOHE zt You re blasting down the trail and you see a hairpin coming up so you let off the throttle which closes the butterfly valve Your 700 Ib Ural is still rolling with inertia keeping the engine rev s high The engine can t get the mixture it s trying to suck in because the butterfly valve is closed blocking air flow To compensate for this there s an air jet in the lower diaphragm chamber that transfers ambient pressure to one side of the coasting enrichener s spring loaded cut off valve The excess vacuum in front of the butterfly valve is transferred to a drilling that leads to the other side of the cut off valve This sucks it open allowing the pilot jet to feed more fuel to the engine preventing an overly lean condition Keihin Carburetor oppozit ru ri 3 I lum 3 f SOCHOHRG cope m OCCUHOHKO De PCIe HEIDI HBVNCHH KDBHIEKG W
3. Be 5205854 Pai up ho r ic E Ree 5 2 m I i AA rai b LP aoo 16020 RH IN OUT beca IBOZOA LH IN OUT E VQ Float Chamber H 4223 IMZ 8 128 15001 93500040081H 12908802000 14028462200 12298007000 N425 6NE00 N41303C00 991013931220 991013931250 N42425B38 N42425B40 16155ZG8L100 N42431065 10528292100 09018146000 11988102002 93500040141H N44602C00 IMZ 8 1037 15157 Carburetor Keihin Coil spring Vacuum Piston Comp Spring Seat Jet Needle Needle Jet Holder Main Jet 122 Main Jet 125 Slow Jet 38 Slow Jet 40 Float Valve Comp Starter Jet 65 Float Valve Float Body Gasket CO2 Adjust Screw Cap for Carburetor Breather Float Valw J Y Qf gt Pen Pin 8 9 1 1 Slide Spring 2 Slide Diaphragm Vacuum Slide 9 Needle Jet 6 7 2 S Am r J Jet bes E w Air Jet H a Noodle Jet Main Air Jet i 5 ja Md 5 5 i i WP Pilot Screw v m E Pilot Jat Slow Jet Main Jet 3 os 1 1 ii 38 Jet 0 38mm or 0 0149 in 45 jet 0 45 mm or 0 0177 in 125 Jet 1 25mm or 0 0492 in Vacuum Port Main Air Jet WN po 1 Main Jet n le 5mm Pilot Slow Jet Pilot Slow Jet Idle Mixture Adjustment Screw 0 Throttle Plate Round Slide vs Flat Slide vs Butterfly Throttle Valves 0 th Ht IX 5 o Round Slide Throttle Valve
4. Diaphragm Chamber Full Closed Venturi Enrichener On Enrichener Off Starting The enrichener is referred to as the choke But that s a misnomer When you apply the choke lever what you re doing is retracting a plunger that opens a tube connected to the starter jet allowing additional fuel to enter the venturi Just below the vacuum hose nipple supplementing the pilot system at start up 2000 2003 Patrol Keihin and Gear Up Enricheners Keihin Carbs Do Not Have a Choke but Use a Mixture Enrichment Circuit or Enrichener Enricheners Work by Opening a Secondary Fuel Circuit below the Throttle Valve Circuit Works Like Idle Circuit Supplying Extra Fuel when Throttle Is Closed First Enricheners Used on Urals Imported to U S to Satisfy EPA 32mm CVK Keihin 2000 present e When Engine Is Cool or Cold and Ambient Temp between 40 F 60 F 5 C 15 C Pull Out Both Enricheners to Start As Soon as Engine Starts Immediately Push In Enricheners Run Engine at Moderate Speed for 30 60 seconds o If Engine Starts to Die Blip the Twist Grip Throttle rapidly twist part way towards full throttle and then back off to Keep Engine Running After 1 to 3 minutes Depending on Ambient Temp Engine should Run Smoothly without blipping the Throttle o If Engine Is Cold and Ambient Temperature Is below 40 F 5 C Give Engine 5 10 depending on how cold it is Priming Kicks with Ignition Off Gets Some Oil
5. In to 4 _ Supply an Increasing Percentage of Total Mixture a 4 Up to Full Throttle gt eec When You Set the Idle with Big Screw on Right Side of the Carb What You re Doing Is Covering i or Uncovering One or More of the Four Small rr Holes that Are Drilled into the Venturi leading to the pilot jet Just under the Butterfly Valve and 4t6 o clock in the mouth of the Letting More or Less Air Pass the Butterfly carb you can see the end of the When You Adjust the Pilot Screw under the 0 A carb You Are Varying the Amount of Air Pre im atii sta Mixing with the Fuel before It Enters the Venturi 3 Pilot and Coasting Enricher Drillings Main Sys tem Redondo Ron 1998 www gadgetjq com Top Chamber Separated from Bottom Chamber by Rubber Diaphragm Bottom Chamber Is Open to Atmospheric Pressure When Vacuum in the Top Chamber Rises Sufficiently the Constant Ambient Pressure of the Lower Chamber Helps the Diaphragm Valve Overcome the Downward Force of the Diaphragm Spring and It Rises from the Venturi As the Diaphragm Valve Is Raised from the Venturi Depression lowest pressure area the Needle is Pulled Further Out of the Needle Jet Exposing a Thinner Portion of the Needle Taper Which Allows Even More Fuel to Rise into the Venturi to Meet the Increased Engine Demand Holder SSH EA WWW M ny a Bottom View Bowl Drain Top View Diaphr
6. Circulated to Key Internal Parts Engage Enricheners on Both Carburetors Engine Should Fire Depending on Temp for example when the ambient temperature is O F it typically takes about 5 10 rotations to start Engine When Engine Starts Disengage Both Enricheners after a few seconds e Back Off on Enricheners as soon as Engine Sustains Itself without Stalling Since the Ural is Carbureted Air Cooled Engine Plugs Will Foul Quickly as soon as one minute If Engine Mixture Too Rich If One Plug Fouls and Other Doesn t Engine Will Run Unevenly and May Cause Internal Damage When Engine Is Hot Do Not Enrichen Carburetors Risks Flooding Engine If the ambient temp is high 60 F 15 C or above try starting the engine without pulling the carburetor enricheners
7. Fluid Level Is Pulling the Most Vacuum Diagnosing Issues on my Ural Air Fuel Mixture and Carburetor Synchronization October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner e Slowly in small increments Adjust Each Idle Set Screw until Fluid Levels on Manometer for Each Carburetor Hold Even Be Patient Allowing a Couple of Seconds for Changes to Take Effect See yellow circled area below Once Set Steady at Idle Rev Engine to 2000 3000 rpm Levels Should Remain Steady If So Successfully Synchronized Carburetors Turn Off Engine Place Throttle Cables Back into Play Securing Set Screws So That When You Twist the Throttle It Turns Butterfly Levers on Both Carburetors at Same Time and Angle see rog PET area se Screw ES Diagnosing Issues on my Ural Air Fuel Mixture and Carburetor Synchronization October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner Ideal Condition Light Brown or Caramel Color Black Soot Means Air Fuel Mixture Running Too Rich or Too Much Fuel Diagnosing Issues on my Ural Air Fuel Mixture and Fuel Delivery October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner Determine Good Steady Fuel Delivery to Carburetors Check for Good Steady Flow on Both Lines from Y Junction under Petcock Check In Line Fuel Filters for Debris or Obstructions Drain Some Fuel from Each Carb by Loosening Screw on Bottom of Float Bowl Chamb
8. IODOHODOS H JENSEN n i GAKVYYMHKHOZO KPH from Branch Pipe RPMI DOGTHHOGBAM KOJHIGUixoM to Engine lale Aajust 5crev z e pe a a E 3 Pezyuuposouniu om lt pu RoE ECE CMEC 537 1 ed T 1 E 3 0 B V a Drain S rew A DOT CHO OI GL The idle adjust screw sets the speed for each carburetor at rest The drain screw is periodically backed out to rid water and other contaminants Bottom View with Float System Removed oppozit ru m io Engine i CPezHHposouHb 0071771 Kauectiad Ge tECH am Pilot idle Mpdure Scre EETA IZnnGHPRE 7710714 4 BIH Pilot Jet HRJLOD COC Oci xod loat Valve Seat Cem Kanada moneda O from Branch Pipe Removing the 4 float bowl screws and the float assembly reveals the starter Jet main Jet and pilot Jet Float System oppozit ry FIMUEK DecYGnpoexu ypoenus HORG Float Before bending anything visually inspect the rubber tip on the float valve and spray some carb cleaner and compressed air in the valve seat to make sure nothing Is blocking it open LIE i Ta Float Valve and Float Pin JUGHODHGS HOIJAMISODDBOSHHOHHBE KOHyC H HO HBY NCHHOHHIE CHIOADUK VRAD The float is hinged on a pin in the float boss rising and falling with fuel level in the float bowl The small metal tang integrated in the plastic float supports the float valve float needle As fuel in th
9. K 37 PZ 28 K 38 Kaptex VDC RAM K 68 Mikuni VM 28 Jikov 2928 Flat Slide Throttle Valve K 301 K 302 K 62 K 63 K 65 Butterfly Throttle Valve Kethin CVK32 1 One term describing carburetors is round slide flat slide or butterfly throttle valves Flange Mount Bolts Directly on Cylinder Head or Adapter K 37 PZ 28 K 38 K 301 K 302 K 62 K 63 K 65 K 68 Kaptex VDC RAM e Spigot Mount Rubber Compliant Mount to Cylinder Head Mikuni VM 28 Jikov 2928CE Keihin CVK32 Another term describing carburetors is flange mount or spigot mount Keihin Carburetor oppozit ru P 1 Drain Hole ARS ANSA from Branch Pipe Himeuep cnuaa SZ V MOTHE A qo HOHJIGASKOGOR K Mepbi Fuel Inlet N Dosoymuwii 771 14 227 E coedensem 1 HOPRLJWISKOSyRO KUED c amwocgeepo N X Gasket between Upper Ciramber and Float System Enrichener j J OHLONE HimyHep CODacamm HETE EM P Iiiuaur om kpanuuka MAINE The 32CVK is a common type for the Japanese the differences in models are usually in the diameter of the diffuser and nozzles although there are also minor structural differences depending on volume design and model year Keihin Carburetor oppozit ru Throttle Cable Bracket _Tnanne KDOnagenus T mpoca ZONE Vacuum Nipple Eyer Room wees Hpubope OLA CHHXBOHH3SOHHH RODO
10. agm Cap Right Side Idle Setting Screw BT ZU Keihin L22 AA Keihin Carburetor for 750 cc Diagnosing Issues on my Ural Air Fuel Mixture and Carburetor Synchronization October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner Set Fuel Mixture Screw Located at Bottom of Each Carburetor s Float Bowl Turn 2 5 turns from Seat starting point Screw Fuel Mixture Screw Clockwise till It Stops Don t Force It Be Gentle and Smoothly seat it Correct Number of Turns is 1 1 2 turns from Seated Adjust Idle Speed Using Idle Set Screws to Control Amount of Air Drawn at idle into Carburetor s Venturi Chamber Loosen Throttle Set Screws red circled item below and Take Throttle Cables Out of the Equation Don t Want Tension on Butterfly Lever when Turning Throttle Grip ge Cable Out of Channel and Let Hang Loose but Still Connected to Butterfly evers e a Diagnosing Issues on my Ural Air Fuel Mixture and Carburetor Synchronization October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner Remove Black Rubber Caps on Carburetors which Seal the Vacuum Nipples red rectangled item below Use Home Brew Manometer Hook Up to Vacuum Nipples on Each Carburetor see below Left Vacuum Hose Goes on Left Side of Engine Right Hose to Right Side e Start the Engine and Note the Levels which Reveal How Much Vacuum Each Carburetor Is Pulling or Generating The Side with the Higher
11. e float bowl rises the float valve is pushed into the valve seat until it s high enough to shut off the fuel to the bowl As the level in the bowl drops lowering the float float valve pulls from it s seat and fills again Float iaa i oppozit ru F 1 RU iui E 1 Peg E rue y J Py 4 E siah L LB sicomea nomea npu im pezpguspoexe yposens FIORE 0 1mm variance ls rod 0 IJ 5 Ei to Engine from Branch Pipe The float level is the first thing that needs to be checked when tuning your carb If the level ts too high it can cause a rich condition too low and it can cause a lean condition If it s not set correctly any other adjustments you make may have to be redone Idle Mixture Needle of Keihin Carburetor oppozit ru Idle Mixture Needle CZAMDOGOUHPBZ DOJMLKOUCCHGd THICHBHO CODHBGGHICE 8 CGOyIORIeH IOCACO OGGHICIBHOCHH Hc 1 Mixture Needle and Seat Should Be Clean zw c ape oxypamuo expyuueaew e Pay Close Attention to the Two Washers HOHY mobet He biam PIATRA ACT aa Is Underneath the Carb The idle mixture adjustment screw is turned very gently CW until you just meet resistance any further and you will damage the needle Factory setting is 1 1 2 turns CCW from seated Keihin Carburetor oppozit ru 7 3 ONGODCHHS KOHI 0 d Coasting Enrichener Jets CUnGODCHWE KOH
12. er using 3mm Allen Wrench Check Fuel for Water it ll settle to the bottom and Contamination Debris Remove Float Bowls by Removing the 4 Screws Used by Ural and Examine Contents of Bowl for Contamination and Water Replace Easily Stripped Screws with Allen Headed Stainless Steel Screws Blow Out Any Gunk in the Jets within Carburetor s Fuel Paths Best Way Is to Take Carburetors Apart and Do a Thorough Cleaning of the Jets and Liberal Use of Carburetor Cleaning Spray while Examining the Components Following Procedure is Quick and Dirty Way of Clearing Fuel Path but Not a Long Term Solution Do This with Little or No Fuel in Float Bowls Some Fuel Works Better as It Acts as a Hydraulic Force thru the Carburetor Jets Plastic Elbow Piece vent mechanism on Side of a Keihin see light blue circle When You Blow Air Through It Will Exit This Vent sm j Stainless Steel Allen Head Screw Upgrade Kit for Top Cover and Bowl Chamber of Keihin Carbs ge ILI ILL 8 Screws for Top Cover 8 Screws for Bowl Chamber Helpful upgrade kits to allen head stainless steel screws are readily available from Heindl Engineering and Holopaw Gene Diagnosing Issues on my Ural Fuel Delivery Fuel Path October 10th 2009 Domingo Chang Colorado Motorcycle Travel Examiner Blowing Out the Fuel Path Use Manual Air Pump or Air Compressor Set for 20 PSI max with Cone Adapter to Snugly Fit into Fuel Line s Openin
13. g Ensure Fuel Petcock Is Closed o If Petcock Isn t Closed Fuel Will Come Out the Lines Disconnect Fuel Filter red circle from Each Carburetor Leave Short Length Fuel Line blue arrow which Connects to Carburetor Itself Connect using a plastic cone shaped adapter Air Hose to Short Fuel Line Holding It Tight to Get a Snug Fit Place Wad of Shop Towel Paper against Opening of Carburetor s Vent and Blow Two Quick Sub Second Blasts of Air into Fuel Line Most Fuel Caught by Shop Towel Wad of Paper Do Both Carburetors in Same Manner After Loosening the Gas Cap Blow Air thru Length of Fuel Line which Was Connected to Fuel Petcock Ensure End of Fuel Line with Compressor Is HIGHER than the Fuel Petcock When Open the Petcock to Open the Fuel Path into the Gas Tank Hearing Air within the Tank Gives Confidence of No Debris in That Portion of Fuel Path Button Things Up and Go for a Test Ride Carburetor Enricheners wwwgadgetig com Carburetor Enricheners Provide Extra Fuel to the Fuel Air Mixture Allowing a Cold Engine to Start and Run until Warmed Up Sufficiently to Allow Normal Operation o Pulling the Enrichener Retracts a Plunger that Opens a Tube Connected to the Starter Jet Allowing Additional Fuel to Enter Venturi Just below Vacuum Hose Nipple It Supplements the Pilot System at Start Up Use Caution When Using Enricheners as They Can Easily Cause Engine to Flood or to Foul Spark Plugs Si Lower
14. he 28 mm Mukuni was introduced in 1994 to meet EPA requirements on imported Urals later replaced by the 32 mm Keihin CVK32 Keihin Carburetor Bleed Type Carburetor Variable Venturi Controlled by Constant Velocity CV Also Known as Constant Depression or Constant Vacuum CV is Next Best Thing to Electronic Fuel Injection Feeds Precise Amount of Mixture to Smooth Out Throttle Response Reduces Pollution and Stretch Fuel Budget and Gas Tank Range 2327 Represents 32 mm Venturi Exit Diameter Butterfly Valve Instead of Round Slide or Flat Slide Throttle Valve Evidenced by the Rotary Movement on the Side Throttle Cable Connected to Butterfly Valve Varies Volume thru Venturi Nominal Jets for 650 cc Main Jet 118 Nozzle Idling 38 Concentrator Nozzle start 65 Please See Part 13C for Re Jetting of Carb 2002 CMSI 750 cc 38 some had 40 and 125 2003 and early 2004 IMWA 750cc 38 and 118 Late 2004 bikes 38 and 125 ii 2005 thru 2007 38 and 125 Ducati Ignition starting with 2007 7 bikes The Keihin has a butterfly valve much like is commonly found in automobiles Variable Venturi Getting Sucked In Redondo Ron 1998 www gadgetjq com e Venturi Is a Tube with Convex Taper one end wider than the other As Air Enters Wider End It S Squeezed into Narrower Section of Tube Lowering Air s Pressure Area of Lowest Pressure Is Just Past the Narrowest Point Lowest Pre
15. hen re building the carb check that the needle holder is mounted evenly on the needle Spread the diaphragm and gently cover with a lid do not over tighten the screws to avoid damaging the sealing skirting of the diaphragm 2003 Patrol 32mm CVK Keihin Seike Carburetors Vut TE Compliant Carburetor Gasket Enrichener ES WEBB a k a Choke 3 SMART wE E a Never use a metal adapter between the carburetor and cylinder head 2000 Ural Carburetor Troubleshooting Chart PROBLEM CORRECTIONS Hard Correct use of enrichener Disassemble carburetor and chemically clean Float stuck Remove float bowl check float operation and correct or replace Float damaged or leaking Replace float Intake air leak Check carburetor mounting flanges for air leaks Ignition problem Repair replace or adjust as necessary Low cylinder compression Repair replace or adjust as necessary Poor idle Idle speed adjustments are unequal Equalize throttle stop settings or stalling twin carburetor models and multi carburetor models using individual throttle stop adjustments Clogged idle and low speed air bleed Disassemble carburetor and chemically clean Pilot Sys CEM Redondo Ron 1998 www gadgetjq com Pilot System Supply the Air Fuel Mixture at Idle I 7 Continues to Supply Fuel throughout Entire L TIT r7 Throttle Range 13 Ul iS After about 1 8 Throttle MAIN SYSTEM Cuts
16. ssure Point Called the Depression e Bernoulli s Principle States That This Lowered Pressure or Comparative Vacuum Is Separate from Engine Vacuum Variable Venturi Varies the Venturi Diameter at the Depression by Raising or Lowering an Obstruction This obstruction is Called a Slide On a CV the Slide is Called a Diaphragm Valve Valve slide Butterfly Valve for Keihin Engine ees Vaso l o en Q0 Atmospheric cOo o o Pressure Almospheric E A e Pickup Tube Pressure 15psi 1 Needle Jel TE ene Mixture GAIR FUEL Main Jet CVK32 Keihin Carburetor E1512 p L83 18005 E E r5 n D n j pa rj 3 rz E puis 2 i he E E 1 ELE T JE bs oy 3 C ap 16014 x 2 n L 1 z Wu dux m Am 82081A e I EF ew d E uw E 7 y F M p i j ji 55 tA a s E f 7 Le Sa SA EDD NM E oe a Slide s SENE 4 0 18012 ze Spring EE 5 18017 92055 o S2084 7 Needle Jet s20 2 m Pilot J t Inl 16030 I ll Needle Hold 13041 F at Valve T dd d aAirTube t 10008 18044 dus i 3208 1 3 1601 i 8 063 478 E Main Jet Idle Mixture Needle se 206 3 ni Y LE E i828 em NM ED Ao We i ien Se Diaphra m Floats lak 92043 pnrag Float Pin uu M 5 3 32055B8 E Jl Float Body Gasket
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