davefrombc

Clean the carb and look closely at it for plugged holes in the sides of the jet tubes . Blow out the passages in the carb too. Your description of the problem is classic lean running from fuel starvation caused by a plugged jet or passage .

I know the laws of Fla. are a lot different from those here in many things, but here ATVs used to be sold without vehicular registration ( titles). They changed that a couple of years ago, using the excuse it would cut down on theft, but I suspect it was more on the lines of more tax each time the ATV changes hands just as it is on other vehicles. New ones are now registered when sold and all old ones needed to be registered. There was no problem if you bought used from a dealer, or from a previous owner who had registered it and gave a bill of sale. Those of us who had ATVs never registered had to get a notary to certify a declaration that we legally owned the ATV. With that declaration and the serial number, we were able to get our DMV to register the ATV to us. From that point on they are treated like any other vehicle . Hopefully your DMV will do the same : accept a notarized declaration of ownership and register the ATV to you after clearing the serial number

You might be able to find some rubber cups the right size in automobile parts and just hone / clean up your old cylinders rather than try replacing them with new . Here is an ad on Amazon.com for rebuild kits for your cylinders .. Pricey at $39.95 a side though . https://www.amazon.com/Front-Wheel-Cylinder-Repair-OCP-06-502/dp/B00Z70L2LY There are also other advertisers on the Amazon.ca site listing them , but at US prices and of course insane shipping charges from the US. If you're in Canada , get a friend inthe US to order them for you and they get free shipping . Shouldn't cost a bundle for them to parcel post on to you; or if you can do down for a visit and pick them up there .

Sounds like you have it idling a little too lean . Try adjusting the idle air screw .

Just go directly to the starter terminal with jumper cables to see if the starter spins over .. If it does then it's time to trace the circuit out to find the problem. It could be in a relay, connection or broken wire. I'm assuming the battery is charged and there's no blown fuses .

OK . It won't be the rotor. I'd suspect the voltage regulator, or the stator if you were getting bad readings from it. Can you possibly borrow another voltage regulator to try ? Voltage regulators can fail low as well as high . It is a little easier changing it than the stator. I like to try to eliminate the easy before going for the harder . Is the ac voltage the same across all 3 windings on the stator? Are you using a true RMS reading voltmeter or one of the cheapie utility ones ? . The cheaper ones usually read low, and some can read considerably low especially if the ac has a varying wave form or cycle rate. Have you opened it up to get a Look at it and the pick up coil for the ignition. I don't know your particular machine model but at least on some machines the pickup coil for the ignition could come loose and the gap could be wrong .. Gap between it and the rotor should be about .010" Is the clip in the top notch on the main jet needle. If it isn't, try that to lean it out. Otherwise the only way to tune it for your altitude would be to rejet to a size or two down. Sorry but beyond those suggestions I can't be of more help.

Check the battery voltage . . Even a month old battery can fail or be dead if there was a drain on it while sitting .

When you checked the voltage at the battery, what readings did you get ? .. Engine off battery should read around 12.6 volts. . Engine running revved up a bit voltage should read 13.8 to 14 v. If it does , your alternator and regulator are fine. The running symptoms you describe sound more to me to be fuel related. If you are getting any smoke and carbon fouled spark plug it is running too rich , and if the plug is dry and very light brown to whitish it is likely too lean. Check the carb again for holes in the diaphragm and plugged jets . Check also for good fuel flow to the carb. There could be a restriction in the line or in the inlet needle not allowing the fuel bowl to stay full under full throttle demand. The rotor will not be the problem. Magnets do not lose their magnetism and unless the very unlikely occurrence of one coming loose there is really nothing else to make it fail electrically . Most often when there has been a problem with the ignition breaking down at higher revs, it has been voltage regulator problems others have found . If running voltage remains around 13.4 to 14v at the battery the regulator should be fine. There is an inline spark checker you can get to see if the spark plug is getting spark all the time. If there isn't one available from you suppliers you could order one online . `There is the possibility of the CDI box or ignition coil breaking down at higher rpm, but I'd thoroughly check out the fuel and carb before blaming other components. Something else to consider, some quads won't run right at off idle speeds if the air cleaner box is not closed and the filter is clean and in place .

OK. .Sounds like you need to pull the carb and clean it . .You likely have a plugged high speed circuit. either the main jet or passages . The idle air screw should be on the side of the carb rather than the bottom. It is definitely too lean under load off idle.. I believe that carb has a diaphragm that opens the main jet . Check it for holes too. Changing the setting on the idle air screw should have large effects on the quad running . .in fact , it turned in too much it should stall. That's why I suspect the screw you were turning was not the idle air .

That sounds to me like it is running too lean at idle. Try setting the idle down to normal with the choke in and then work from there. You may find you have to readjust the idle air screw a bit richer when you do that .. At speed I think you are losing power and fouling the plug because it is running way too rich when off idle and warm.

Try going up a notch on the main jet needle to lower it in the jet (lean out the main) Idle air needle has little effect on the mixture when off idle. Sounds like you're still running rich.

Head scratcher for sure . About the only thing I can suggest is a possibility of a restriction on the inlet to the air box or filter causing it to draw hard and run lean and possibly draw air from the crankcase vent, and with it a little oil. Idling, running cold and at lower rpm the restriction wouldn't affect it as much as it would at higher rpm and hot .

View File SPARTAN 500 Owners Manual Owners manual for the SPARTAN 500 Owners Manual Submitter davefrombc Submitted 04/27/2018 Category Other ATV  

CFMoto 500 owners manual View File Owners manual for the 2007 -09 models. Those for newer versions are downloadable from CFMoto at their website https://cfmotousa.com Submitter davefrombc Submitted 04/27/2018 Category CFMOTO ATV  

View File CF Moto 500 Service Manual Service manual for the CF Moto 500 CF500-5 SERVICE CF500-5A REPAIR MANUAL Submitter davefrombc Submitted 04/27/2018 Category CFMOTO ATV

I found an owners manual and a service manual for the CFMoto 500 and uploaded them to the downloads section of the forum.. That hose appears to be the carb diaphragm vent hose in the service manual. I don't see it illustrated connected anywhere , but I'd guess it could be connected to the air box.

There is a clip that sets the depth the tapered main jet needle goes into the jet. If the needle is set too high (clip in a lower groove) it will run too rich. If it is in fact rich too rich ,try moving the clip up ne notch and try again . You may need to do it a couple of times to find the sweet spot.

It helps tremendously if you say what machine the carb is used on. A quick search on the net should bring up pictures of the carb in use on your machine and where the hose connects.

Try adjusting the air screw first .. The 2 1/4 setting is just the initial setting and could need some fine tuning .. You want it where it starts and idles ok and doesn't bog when you open the throttle. It's abit of fiddling between too rich and too lean . You may also need to adjust the height of the main fuel jet rod so it gets the right mixture at your altitude. try moving the clip up ( needle deeper in jet) if it seems to be bogging on too rich for your altitude .. Moving the clip down will richen the mixture on the main if it is too lean .

All their engines are similar but their transmissions and drive systems can have significant differences Some have gears and clutches , both manual and automatic and some use a belt drive and 2 variable clutches to create a Continuously Variable Transmission type of automatic.

. It is either splines have worn out on the pinion shaft,or possibly between the crown gear and output to the axles. . When you have it in 2WD, the rear differential is what moves your machine . The reason it moves in 4x4 is because the front differential is pulling the machine along. You'll have to take the rear drive apart to find just what is gone .

Sounds to me it is too lean . Try turning the idle air screw out a little more. You might also pull the carb apart again and check for tiny posts on the side of the the tube the main jet needle is in. One or more of those tiny orifices could be plugged. I is not starving for fuel instantly when you give it throttle , it isn't getting the right mixture. That points to a blockage of or setting > make sure there is no hole in the diaphragm of the carb and the vacuum line and any breathers are routed and connected properly .