davefrombc

Something you could try with a cold engine. Try jumping across the temperature sensor to turn on the fan and see if it still stays latched on when you disconnect the jumper.. Don't disconnect the temperature switch, just jumper across it.

What I was saying in the last paragraph is that if there is a hot wire to the fan when ignition is on or off, and the temperature switch switches the ground side of the fan wires then a spurious ground would keep it running....From what you say , once the fan is turned on by the temperature switch then it stays on until the coolant cools to the point the switch opens whether the key is on or not. It sounds odd to me, but that may be the way it is designed and there is nothing wrong. I have no idea if that is the way with your machine , but I know in the automotive world that is the way some electric fans work and also some oil pumps for turbo charger coolers. My reference to "Fun" was really meant to refer to the frustration that is far too common trying to trace down electrical faults... It certainly isn't enjoyable .

The thermostat shouldn't cause the fan motor to keep running ..unless there is an electrical connection to it. The temperature sensor should only trigger a relay to start the fan. Whether it also shuts it down when the temperature drops is the question. The fan breaker is likely just there to act as a resetable fuse, it could be integrated with the fan switch, but I don't know.. I would say the fan motor relay is the same as the fan switch; just different wording for the same item in different publications. Does the fan shut off when you turn the ignition off, and not start from cold until the coolant reaches operating temperature? One thing I noticed in the wiring diagram I saw for the 750 is the fan motor shares a common connection to another sensor , I forget which it was , an air temperature one I believe. I wonder if those switches are wired so that the positive wire to the relays is hot and they are switched by the ground side , and a faulty ground in the circuit is causing them to trigger.. Where I get all the questions from is your statement the fan shuts down if you disconnect the temperature sensor. The problem you have with the fan has to be something in the circuit it is part of. Either something staying latch on, or maybe as I a faulty ground in that circuit i=or one connected with it . Isn't tracing electrical problems just a whole lot of " fun" ? More than one person has had a balding problem because of them.

Check the shop manuals posted for the Brute Force 750.. The wiring is most likely very much the same for the 650. Here is the link to download the 2008 manual for the 750 in the forum's downloads section ( Mouse over Browse and click Downloads to find the lists of all the manuals and information there) :

I would contact Yamaha and ask them for assistance ... Since your d number is so low , my guess would be it could be 124.33 , and the crankcase number 12 (.12) Please don't take those guesses as accurate .. It is merely speculation on my part. Hopefully you can get a response from Yamaha to help you . Here is their contact page for Yamaha Canada . https://www.yamaha-motor.ca/our_company/contact_us.php

According to what I could find the AC motor is actually built by Kymco. The 366 has an 81 mm (3.188") bore. This L.A. outfit sells a sleeve kit for them. . I couldn't find any mention of oversize pistons, so it may be sleeving the bore and new stock piston is the only way to go. https://www.lasleeve.com/downloads/2013-Catalog-ATV-Section.pdf

Did you also change the oil and filter?.. Water vapor could be coming from water in the oil boiling off and entering the intake through the breather tube for the crankcase. Try adjusting the idle air screw and or the needle valve settings. Bogging on acceleration sounds like it isn't getting enough fuel (running lean) when you open the throttle.

The problem could be in the stator or the pick up coil. The regulator shouldn't have had anything to do with the lack of spark.

That sounds more logical to me .

Water pump can't run if the motor isn't running unless it is electric, and fan shouldn't run unless the water temperature is over it's turn on point.. If you haven't changed the relay, that's what I'd suspect the most. If it has an unswitched hot wire then it could be feeding the power to the sense side of it and keeping it on. Something in the fan circuit is getting power with the ignition off. The water pump runs with the motor. The fan should only run when the motor reaches it's turn on temperature. You changed the temperature sensor, so most likely culprit is the relay itself. I can't see an electric water pump or any other circuit feeding the fan. Have you disconnected both the hot and ground jumper wires you installed ? Your extra ground wire could be the problem if for some reason the relay in that circuit switches the ground rather than the hot wire .. I'm only giving you stabs in the dark since I don't have an electrical schematic of your circuit to make guesses from.

Let us know when you find the problem.. I never thought to mention it before, but it might be the relay itself at fault.

My old Honda 300 FW has pulled some pretty impressive loads too. For the uses described, I would think a 250cc would be sufficient. I'm one of those that isn't over weight .. I'm just under height..... at 260 pounds I should be about 7'6" . I'm about a foot and a half short .....my quad takes it with no problem and still pulls a good load when called upon to do it .

Somehow the relay is getting voltage to stay locked on. Something in the circuit is feeding power to the relay even with the ignition turned off (some kind of feedback loop that you break by disconnecting the sensor). Try disconnecting your bypass and see if that fixes it. It also could be a problem with the relay itself. I can't help further beyond those suggestions .

Are you sure you wired the new sensor in properly? It sounds like it is latching on. There should be no power to it or the fan relay with the ignition turned off... I would suspect your bypass circuit that you wired in may be causing the problem.

The red wire for the switch (assuming it is just the wire to take power to the switch that activates the solenoid) can be connected to any wire that ignition switch is turned on, and off with the ignition switch.. You could connect it directly to the switched side of the ignition switch if it is easily accessible.

I'd tell the dealer where to place his $650 carburettor. You can buy one online for ~ $165 and a rebuild kit for your old one $16. both are offered with free shipping in the US. http://www.ebay.com/bhp/yamaha-bear-tracker-250-carburetor

Sounds to me a second tear down and cleaning of the carb is in order. Check the float height setting. Make sure it is not binding and the needle moves freely. It appears the motor is starving for gas. Check the idle jet setting, and its air jet for it for obstruction.I did a search on your carb and I see it has a vacuum operated secondary throttle control so a careful check of the diaphragm is in order too. Also check the carb to block connection for air leaks.

My guess is a loose or corroded connection or a bad ground. I would look at the ground connections first , then the main power wire . Tracing electrical problems are always "fun".

When the engine revs up the clutch on it closes up to grip the belt.. as the engine clutch closes more, the belt rides higher in the clutch. At the same time the driven clutch opens up, allowing the belt to ride lower in the groove to increase speed at the wheels. I don't see movement in the drive clutch at all, but I cannot point you to the problem with it since I don't know its internal mechanism.

I didn't see the clutch closing at all.. It should close when the motor revs up whether there is a belt there or not. At idle , the motor clutch is open and the driven is closed.. The belt is slack so the motor can run without driving the machine .. When the motor revs up, the clutch should close to grip the belt . Here is a youtube video of one in action.

It looks to me like the clutch on the motor is faulty.. As the motor revs up ,that clutch should close up and grab the belt.. I don't see the clutch closing up at all.

You can download a copy of the service manual here: http://www.mediafire.com/file/oj3p8rysdnv921n/1985-1995_Polaris_Atv_Service_Manual_Repair_All_Models.pdf You should be able to find the wiring diagram there. . I don't envy you the task of tracing the wiring on a butchered system. It is just over 100 MB ...a little more than 1 MB over the file size limit for posting to the Quad Crazy manual library.

It sounds like plugged jets in the carb to me. It's not uncommon if it was sitting for a long time with old gas in the carb. A disassembly,good cleaning and fresh gas should fix it.

Can't help at all on the depreciation rate . I think it depends a great deal on the brand and model, as well as the state / province you are in. Far too many factors come into play when looking at depreciation. I do know that the big names , Honda, Kawasaki , Yamaha and Polaris tend to have a slower rate of depreciation compared to lesser known rides. Honda likely has the lowest rate of depreciation of the lot. I do know, like cars and boats, you do see the highest depreciation from the time you take it off the showroom floor to the end of the first year. After that the rate of depreciation slowly lessens until they seem to float at approximately the same price for 10 years or more. Some models 20 years old and older sell for close to the same price they went for when 10 years old.

I can only go by what the banks and car lots as well as other places that offer high dollar loans offer here. Banks usually beat finance companies and dealers on rates . The system is different in the US so I cannot tell you which would be cheaper in your state. That's where you have to ask and compare when considering financing. I also can't give any insight on how long a term they would offer either in Canada or the US because I don't buy new or on credit. I'm rather old school in that respect .. If I can't pay it off when the bill comes in , I don't buy it . Visa doesn't like me because they only get their percentage from the sellers .. My balance is paid monthly so there is no interest charge. What's right for me isn't necessarily right for others.