davefrombc

When you find out why you couldn't bleed the rear brakes please be sure to post up the solution

Do you develop pressure in the master cylinder to operate the front brakes with just nothing going to the rear? If so , there has to be a blockage somewhere in the line. I'd start at the rear cylinder.. Remove the line from the cylinder and see if you have fluid under pressure from the hand brake. If so, then the trouble is in the caliper. If no fluid, reconnect it and go to the splitter where the fluid is divided between front and rear. If you have fluid there , then go to the next connector and see if you have it there. The blockage will be between the last place you had fluid and the caliper on the rear. I can't find a diagram of the hydraulic circuit for the brake system so I have to make simple guesses and suggestions for things you've probably already tried.

No idea on the plumbing on that quad's brake system , but some of the older cars with a single master cylinder feeding both front and rear brakes had sliding valves to block the line to the brakes on front or rear if a line was damaged . The sliding slug needed to be reset after repair . Have you tries "reverse bleeding" the rear brakes.... Pump fluid from the bleeder back to master cylinder to see if that works ? Otherwise either the line is crimped or blocked somehow between the master cylinder and the brake cylinder.

Did you check to make sure the bleeder hasn't been plugged by dried mud? You may have to remove it to clean it out. With the bleeder screw out you should see fluid come to the cylinder. If not there is a problem between the master hand operated cylinder and the brake cylinder.

That sounds like the transmission might be stuck in both forward and reverse at the same time. The motor will bog because the clutches lock up and the transmission won't let it move. It could be something came loose on the shifting forks allowing both forward and reverse to be engaged at the same time. I don't know your machine so I can't say whether it is an external adjustment or if you'll have to open the transmission to fix it .. Likely an inexpensive fix, but a PIA to do . There is a service manual in the downloads section that should cover your machine .

I am a Honda guy, but in my opinion you can't go wrong with any of the machines made by Honda, Yamaha or Suzuki in any of their 2 or 4 WD versions. Looks like a great find if the internals are as clean as the exterior.

You only need a small ruler to measure the float height although gauges are easier to use accurately .From your description it still seems to me to be running out of fuel ( way too lean) at higher rpm.. That can be because the floats are too low not allowing the fuel bowl to fill to the proper level, a restriction in the fuel coming into the carb, a partial plugged passage or possibly undersized jets. If you still have the OEM carb for the bike try comparing jet size between it and your new one. Sorry I can't help more than offer those suggestions to check.

Check the float level. It may be set too low, and make sure there is no restrictions in the fuel line or possibly in the fuel valve. Your description indicates to me it is running lean/ out of fuel at wide open throttle.

My guess is a wonky temperature sensor. Like all electronics / electric relays and switches , they can go intermittent---- work one time and not the next, then work and fail again at random times. I'd replace it and see. I'm not a Honda dealer or service mechanic but I can't see their thinking in replacing the fuel pump and filter when the bike runs fine until warmed up to the point the fan should come on. That's not a fuel starvation issue that should show up well before the motor reaches operating temperature. That points far more to a sensor/ fan circuit problem to me.

Rather than suction , pushing fluid back from the wheel cylinder bleeds to the master cylinder can clear an air lock if that happens to be the problem. Used that a few times on old auto systems that didn't want to clear trapped air through normal bleeding.

I read through the problem posts and try to offer help when I can. Not a lot of help to offer on any particular machine since I'm only familiar with my own , but I can try searching for free manuals and answer some or make suggestions when searching out carburetion or electrical problems. I have no experience with the new electronic systems . I'm from the carbs,, points and coil days of old.

I searched and like you didn't find a great video or instructions for adjusting your carb , but this exploded view parts list will help you identifying the parts. The idle adjustment looks to be the screw by the fuel inlet. The coughing , backfiring and uneven running is most likely caused by running lean. It is either a setting out of adjustment or there is still a partial plug somewhere.. I hope this helps. https://www.partzilla.com/catalog/yamaha/atv/1989/moto-4-yfm250w/carburetor

Yes definitely clean the tank too. Get all the old gas and any sludge that settled out of it out .. I have an ol tiller that gas was never drained out of and it sat for years . There was still liquid in the carb but a sticky goo had settled out of it .. The seat for the float pin was plastic and swollen up as well as jets and passages were plugged .. I ended up replacing the carb. I had to completely fluch the fuel tank because it also had that sludge in it .

That's a strange one indeed. Does the battery read the full 12v + with the motor off and just that lower reading when it is running? Turning lights or other accessories on with that low a voltage should kill it rather than make it run better .. I'm wondering if maybe there is a bad diode allowing AC to cause false readings on your voltmeter. What are the readings with everything turned off , when ignition on but nothing running and is it always that low a reading with the motor running? Can't help more than to just suggest those checks to help you diagnose or someone more knowledgeable than me to use to help you diagnose it further .

THe small jets being plugged are most likely the reason it's not running at all. The big jet is the main one for large throttle openings . The smaller jets and holes are for idling and part throttle.. You can use welders torch tip cleaners to poke out the clogged jets. Blow the passages out with "canned air" like they use for dusting out computers .

The first digit represents the country of origin. The most common are: 1 or 4 = USA 2 = Canada 3 = Mexico J = Japan K = Korea E = England W = Germany Z = Italy 2nd and 3rd letters signify Arctic Cat 4th and 5th are model year 6-8 are type (SNW snowmobile, ATV, MPV prowler etc) 9th is a check digit 10th is the last digit of the year (9 = 2009, A=2010, B=2011, C=2012 etc) 11th is a "T" This one I don't know why, just that its always a "T" 12-17 are the "serial number" Your Cat was made in 2010

Glad to see the site back up. I hope everyone had a great Easter weekend.

If I read the schematic right the neutral light (19) and the path to ground for the starter button relay (11) should only be on when the neutral safety switch ( 20) is closed. That would indicate to me the problem is in the mounting of the neutral safety switch. For some reason the switch is open when in neutral and closed when in gear. There is either linkage not set right or is it possible to mount the switch turned 180 degrees? Disconnect the wires from the neutral switch and check for continuity in the switch .. In gear it should be open ( no reading on the meter) and some value close to 0 when in neutral. YFB250 Service Manual - 7a894ceb-c5b6-4f18-a285-6e8cf99f52fd.pdf

Yes it was search results. One of the sites claiming to have a pdf available was either a bait site or had been hacked so that when you went to download the "pdf" a pop up came saying an update to my browser ( Firefox) appeared.. It likely would have substituted the name of whichever browser was being used. It is a fairly common exploit that traps the unwary. Any time I spot something like that when searching to try to help others, or in phishing e-mails, I like to warn others of them. I usually post about them in my Facebook so my contacts know of them and can spread the word to their contacts . Far too many people use their computers but are not really aware of the various exploits out there so are too often vicitimized by them . I just use Microsoft's own anti-virus and my own "spidey sense" when browsing and checking e-mail. I also occasionally scan with Malwarebytes for adware and similar crap. I also subscribe to a couple of tech news services that often give heads up on new exploits out there. Being retired, I have a little more time to do searches and browsing on the computer so I am often a little more able to find information for fellow forum members who may not be quite so familiar with computers , searching and the various forms of malware out there .. If my warnings help even one perso evade the pain, frustration and expense of an exploit, I'm happy . I don't mind others in some of the forums I'm in grumping about my warnings because the exploits are old news .. Far too many others aren't familiar with that old news . My posts are for those it'll help , not for the " know it alls" .. LOL No matter what anti-virus you use, it's always best to occasionally check with something like Malwarebytes too. . Norton is among the best pay A/Vs but I quit it years ago because I found it a resource hog . Microsoft has greatly improved their built in A/V for basic protection . There are plug-ins for Firefox and the other browsers that also add a layer of protection and an awareness of the many exploits out there so far have kept me safe without spending a bundle onpay services . For those interested , here's the site that regularly evaluates all the main anti-viruses out there.. They're an independent service , not pushing any one product like some "test and evaluation" sites do. https://www.av-test.org/en/antivirus/home-windows/

I hope Jerandangel got the information they wanted and didn't fall for that trojan posing as a browser update on one page claiming to offer a wring diagram download .

Does the motor turn over on the starter or do you get nothing ? If nothing the problem could be the neutral safety switch safety switch or another safety switch is faulty.. If everything works and the motor turns over on the starter then it could be the CDI box ( most likely) or the trigger coil is in the stator assembly is bad. By the way , Be careful if you search for a wiring diagram. I did and found one site that had been compromised by a trojan.. Tried the link to the pdf it listed and got the message the link didn't work. There was another link listed on the page that supposedly went to a download page, it showed a different address and a op up box that my browser ( Firefox) had an important update. That was a trap trojan installer. No, I did not click it . I know my FF is up to date and about scams like that one . Those SOBs catch far too many unwary people and every time I see something like that I post in the forum I did the search to help try to answer a question so if others search they have a heads up that the exploit is out there. See if you can find someone local with a CDI box that fits your machine that you can borrow to see it if it does the trick.. There is a manual in the downloads sectionof the forum but toy need 10 posts before you can get it . Good luck with your quad.

It sounds like a very lean run at idle. If you have thoroughly checked the manifold for leaks I would suspect a carb setting.Did you change the setting on the needle in the throttle slide?. If it is in the top slot try moving it down one notch and see if idle improves. My 300FW runs best with that needle two down from top.

Other than repeating the obvious I can't offer much more . Start at the battery. Make sure it is full charged .Check for a blown fuse or fusible link. Check the terminals and ground wire for loose / corrosion and then follow the power forward to where it is first lost. Check a wiring diagram to see what controls the power to that point, and so on until you hit on where the failure is .. There are service manuals for earlier Renegade 800 models in the downloads section that may have the same wiring diagram as your machine.

There is a repair manual in the forum's download section.

That narrows it down to from the output side of the clutch and transmission then.