Ben1098

that 'll do it. trash may have just moved out from under the needle in seat....meaning the problem could come back again. the suggestion about flooding the engine oil with raw gas needs to be checked. gassy smell test and or over full on dipstick. besides cutting the oil, you will have a rich fuel/air mix when the gas cooks off and is reingested by the crankcase vent PCV system.

need more info on the stumble. cold start up......runs ok at idle BUT A. stumble when the throttle is opened slowly OR B. stumble when the throttle is rapidly opened C. stumble with both A and B. engine warm start up.....the stumble problem goes away or greatly improves???? Now you need to determine if it is a LEAN stumble OR a RICH stumble......simply give a squirt of starter fluid at intake. depending on where you introduce the fumes, there is a delay before the rich mix makes it into the cylinder. Does the motor run easier as in no longer struggling at idle. Get a feel for how the starter fluid boost reacts THEN have someone SLOWLY open the throttle and also try the FASTER throttle blip when the fluid boost comes on. analysis of results......a lean stumble will improve with warmer engine temps. a lean stumble will go away or improve with the boost of fuel introduced into the intake. Side NOTE. 10%, 15%, 20% alcohol gas will have these problems on carb engines set up of OFF ROAD (0%) fuel.....required a rejet tune. ALSO.........some dealers are blending in WATER until phase separation.....then add more OH to get the water back into solution. This trick is really bad for the scooter crowd.

Your Reg/Rect should have 5 wires. 2 are AC input from stator........both G/W.....measure resistance (at R/R connector) of stator windings=.3 ohm ish----depends on meter. Next perform a stator output load test....connect a 40W incandescent to the same wires at the R/R connector....start motor....should glow dim then brighter with higher RPMs.....don't rev until bulb burns out........shut engine down. The next 3 tests check the current carrying capacity of the wires/connections. A "load test" rather than a meter test will better identify the fault. The load is a 12V headlight bulb with a rated current draw of 5 plus Amps......85/85W motorcycle headlight bulb works great. Put 2 leads on the good filament terminals. Test by connecting to the UTV battery.....note brightness. Leave NEG (-) wire clipped to battery NEG (-) post for next 2 tests. BR wire is dead with KEY OFF and 12V with KEY ON......might notice a slight dimming due to extra wire and fuse resistance in the harness. WHT wire has only the fuse back to POS (+) battery post.......bulb should burn slightly brighter....no run to the IGN SW. BLK/YEL is ground.......frame and battery (-) post. SO REMOVE BULB CLIP FROM NEG AND CLIP TO POS POST. Now the test is looking for a path back to the NEG post. Touch NEG Post....bright. Touch frame....bright. Touch starter motor case....bright. Touch the engine case....bright. Touch WHT wire terminal in R/R connector...........BRIGHT. Most common failure is the BLK/YEL ground to harness.....bullet connector. The starter current GND wire (heavy) suffers from electro corrosion......i.e. the steel bolt in the AL case at starter mount.

you most likely have an intermittent connection between reg and battery. the reg can only handle a few open full load dumps before the electronics die. retest connections to battery and ign sw (key ON). old trick.......jumper in second wire in parallel with the 3 wires mentioned......if lives longer than 30 min.....you won...but need to find the bad connection

stator has good output.....PLS solder the cut wires and get rid of the butt splices....trouble down the road. Go to REG/RECT connector. Chase the 3 wires that are not A1 and A2 stator inputs. G wire (according to the ohm test) would be the battery + terminal. B wire would be the battery - terminal. you need good connections from end to end to pass the charging current....same went for the stator powering the light bulb. find an old headlight with one good filament intact. Put on leads and touch to the battery posts.....should burn bright. Do same for B and G at the REG/RECT connector.......this tests the current carry capacity of the harness....5A or so....to pass the reg output to charge the battery.....should burn very close to same brightness.....there is some wire losses in the harness wires. If bright....AOK Next the M wire.....I asked of it went to the IGN sw ON terminal...IF it does, it should be open OFF and +12V (battery) with key ON. This voltage is required for the REG section of the module. TEST AND REPLY BACK

how did the alt output test go? Both the low R value of .2 ohm or so AND the 40 W light bulb load test running motor. I hate the old Kaw manuals that use a meter using ohms for a test for electronic modules......the reading is with the OEM Kaw meter...others will give different readings. Best bet is to use a meter with a DIODE function. This setting pumps 1 ma of current to check the FRONT to BACK ratio of the diode......that is .5 to .6 V in the forward direction and OPEN (OL) in the reverse direction. There will be 4 diodes....not 6......in this regulator with SCRs for the voltage output control. The rectifier diodes need to be tested both FORWARD and REVERSE = 8 tests. you should find A1 has 2 FRW (.5 v) connections BUT they will have the leads reversed. Same goes for A2 input......In a nut shell, the A connection(s) has a POS and NEG diode EACH. 3 phase units will have 6 diodes with +/- diodes to the 3 YEL-YEL-YEL inputs from the alt. Look in a Honda manual for the internal components if interested. 1. Test as such Meter RED + lead to A1. Meter BLACK - to the B (this goes to the BATTERY?)....this would be Forward with .5 v drop across the diode. Next interchange the RED / Black leads. Note what the display has with the meter leads open....you should see the same display when connected this time. Repeat for A2 FR / BK and get same .5 v /open. 2. Next do the A1 and A2 to G wire in the connecter......results should be opposite as these are the NEG diodes this time. Where does the M wire go....my guess it is switched +12vdc.....that is nothing VOLTS and then =12V (battery voltage) with KEY ON. if it does what I guess its for.....this gives the loaded system voltage and works better than using the ground as a charge reference....think voltage drop in the Gnd wiring length of wire.

TRY THIS TEST connect a 40W light bulb (incandescent...not LED) across the output legs of the alt.....unloaded voltage might be 40 Vac BUT if windings have bad connections, the output voltage will be well below the 15Vac needed to forward bias the rectifier diodes...... .5 to .6 Vdc PLUS the battery voltage. if alt output is OK, the bulb should glow dimly and get brighter as RPM is increased. confirm alt output good before rectifier testing. print from manual too small to read....but gathered you have a single phase (2 wire.....A1 and A2). If replying back also show the schematic for the alt. windings and the .3-.4 ohm winding resistance...go back to the cut crimp (very bad idea on high current applications.....solder back in place.

TIP: Running the motor for short times will foul the spark plugs.....the ECM is mapping the cold start-up and will have a rich fuel mix....Run long enough to get some heat into the plug to self clean. Repeated short run times can kill the plug. some T/S tips----you have an apparent rich F/A mixture OR the unburned fuel is wetting down the plug. The problem appeared gradually....start with the air filter. Pull shift and cover...debris on filter and or blocked intake (as in mouse house)...clean and reinstall. Check for air leaks downstream....a LEAN mixture will not light off BUT can wet down the plug. The above REPLY was the air vent for the fuel tank....they used be to routed into the intake runner...newer units have the hose elevated behind the pass seat. If removed from intake, PLUG off the connection...dowel pins work good. Start with new plug or known good unit. Leave the cylinder open for now. Remove all fuel sources.....to prevent over fueling....pull fuel pump connector---no more pump whirl sound on KEY ON and carefully pull the injector electrical connector...no fuel from residual fuel pressure. Spin over the motor for 5 seconds. Install the spark plug now. Spin over again....should not start. Starter fluid....pop in a 1/2 second burst into the intake and crank. Motor should fire and run for a couple seconds....try again to be sure the only fuel source is the go juice. Reconnect the fuel pump (no injector yet)....crank...should be a no start. Time for some starter fluid again....runs again and dies (good so far). Reconnect the injector. Key on (pump pressure build up). should run now. IF NOT OR RUNS POORLY or LUMPY...fuel system problem, ECM, and or ECM inputs. Possible problems: Most common in order BAD E10 fuel....phase separation, older than 3 weeks, moisture droplets. Drain and purge system. Best to get the NON-ethanol fuel as the rubber parts will last longer also. Fuel pump problem---need around 45 PSI Blocked injector----will dribble fuel...can pull injector and check spray mist. O2 sensor failure----pull the connector...if runs better (NO INPUT SIGNAL---thus ECM defaults to a "safe" limp mode).....have also seen the +12v heater problem (too cold to work)...heater OPEN or an intermittent short to frame (like the exhaust sheet metal burr edge). Harness failure in connector or the butt splices hidden in the trunk. ECM failure. Try these tips

Here is a hint on the compression lock.....motor spins great with spark plug out but will stall a few degree(s) BTDC on compression stroke and then reverse when starter button released.....only to repeat the grunt 3 to 5 times and then break thru and have enough momentum to start cranking...... that applies to most ATVs---check the exhaust valve clearance.......also there were some decompression plates that were punched out wrong. This is the spring/flyweight assy held on the outboard side of the cam gear by the two (2) bolts. This rotates and pins the decompression.......the problem is that "some" do not rotate as far as others...meaning that the decomp will work at first but fade away with the valve adjustment. The problem is NOT the two little "pins" in the notch....the flyweight "inside" will hit the round face of the end of the cam....stopping the rotation and thus the decomp travel. This was in several of the Hisun badge machines (Rhino clone Hisun motor which can be used to rebuild the top end of the Yamaha). I used a die grinder/cyl carbide burr to trim a "bigger" inside diameter of the weight........the weight looks like two parts pressed together of which the "smaller diameter" section is what hits the cam end and reduces the decomp rotation. Hope this helps. P.S. don't drop the bolts or decomp parts down the chain cavity as they are "unhandy to access". Lack of fuel due to E10+ fuel-------the alloy metal needle body will actually swell and bind in the float valve body...pull with needle nose and "lightly sand" the 4 corners to give more clearance. The stuff is hard on the carb boots also as I have had some units "A C" that the carb actually fell out of the intake boot after the clamp was released.