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By Dra O
posted a while back - it was running at one point - I have all the plastic shroud off - it's down to frame and engine now
-fuel pump: when line from petcock is attached, no fuel comes out other side to carb; the line to the carb is open (can blow through it); I thought when I cranked engine that the pump would spit out fuel on other side but it does not; I removed fuel pump and opened it up - diaphragm looks good - but internal areas had lotsa calcification build up - I cleaned this out and dried it good - the clear plastic pieces (?diaphragms) aren't broken - the spring w/ steel ball on end moves freely; am putting it back on tomorrow; but can anyone answer about the pump? isn't it supposed to pump fuel through it... to other side... to carb? puzzling
-along with fuel pump: I replaced petcock 3 weeks ago (gas tank had rusty fuel in bottom - cleaned it out prior to new petcock); when I turn petcock arrow NOT to on or reserve, fuel comes out of line; when I turn it to on or reserve, fuel doesn't come out; puzzling
-I don't know what's on back of fuel pump - it's a valve that has a hose coming out of it - looks like it goes to engine/carb - I haven't traced this out yet - what is it?
-can squirt gas on air filter and engine will run for 2-3 seconds then stop - fuel in top of carb (under diaphragm) does same
-it likely needs carb rebuild - will get to this - but something isn't allowing fuel to get from fuel pump to carb
-I THINK it has a mikuni model x carb - diaphragm is ID 26mm OD 68mm - hard to find inexpensive diaphragm, I guess because it's a model x
-last thing - I replaced solenoid due to old one clicking; I HAVE to be charging the battery or it won't start/turn over - battery just goes dead; but if charging, it'll turn over nicely; i'm guessing it's a bad battery
-any help appreciated - I've never owned an ATV before - inherited this beast from grandparent in-law
I have a 2004 Yamaha Bear Tracker in the shop for repair. I have the service manual but it doesn't have all the information I need to fix the problem. I need to know the voltage output of the stator charge coil and pulse or trigger coil at cranking speed. The wiring diagram color code doesn't seem to match and that is compounded by the fact that the wiring harness CDI connector is missing so I have 7 wires that need to be connected to the CDI. I can not find a circuit diagram of the CDI which tells me where the pulse/trigger coil connects or the charge coil connects. The other 3 wires (black ground, orange ignition coil, and r/b ignition kill sw) also need to be connected. The CDI has a single 8 pin connector and has a P/N 4XE-00 F8T19871 -1122 number on it and I believe it to be OEM. However I think the Stator and pulse coil are aftermarket items. I have resistance tested everything and it all seems to be in spec. but I don't want to miss wire anything and cause damage. Any help would be greatly appreciated.
By Scott Sirr
I need to figure out how to clean/fix or replace my neutral switch assembly On my 2008 Yamaha big bear 400 as generally the neutral light doesn’t come on when it is in neutral. To get it to come on I have to wiggle the foot shifter and hold it in just the right spot.
I have googled it and can’t find much on the 400’s. I can’t find a service manual online and the parts manual is super vague.
I think it is in the right side engine cover area, but not certain.
Any help would be great. thanks
By Bronson Weddle
I have a 1999 250 Yamaha bear tracker was told it needed a coil to run got into it to day found out that the kill switch was wired together then I found were they put a new cdi on it they cut all the plugs off the stator wires and the cdi wires I found bits and pieces of wireing diagrams blue pick up wire to red and white green wire to white and green wire rolled it over Had a test light on the coil wire it showed there was juice going to it but no spark on the plug and the coil is a brand new one put it on before trying to test the spark did I miss something or have something hooked up wrong already have plans on a new cdi and stator and pick up coil before I go that far like to hear it run. Thank you for the help in advance
By Dwight Williams
Ok, so I bought a 2006 bayou 250 for 200 bucks, kid couldn't start it and had no idea why it wouldn't run, I pulled the rope and felt what I thought was valve to piston contact, he wanted 500 and I talked him down to 200 and brought it home. Sure enough, timing was way far out, timing chain incredibly loose. So for fun I re-tensioned the timing chain and re timed it, got about 120lbs of compression, pretty low. I cannot get the chain very tight but the the tensioner seems to work fine, the chain guides don't look very worn. Also, when I took the head off the valves don't look bent and the piston has no discernible marks on it. Is this an interference engine? I sure thought I felt some contact with the pull rope but maybe no permanent damage was done? Anyway, I plan on doing a full top end job as well as timing chain tensioners and hopefully that'll cure it. Is there any reason other than chain stretch (I measured it and it's ok) or guide wear that would cause the chain to be so loose? Thanks!
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By Gary Ferguson
My old Big Bear nearly left me stranded but I managed to limp back to my garage just before it died. Now No Spark. I’ve changed the obvious, inexpensive and easy parts- spark plug & coil without any luck.
Ive stripped it down and traced all of the related wiring, checking as many connections as I can but no luck again.
Next I pulled the cover and accessed the stator housing to inspect and do some resistance testing to ID a possible short.
Here are my readings:
Source coil- 325 ohms
Pickup coil- 225
Can anyone tell me if these are good numbers, and if good, where to go next?
I assume my next purchase will either be a new stator or CDI, but since neither of these tend to be returnable items I want to be as sure as I can I’m gonna get a resolution to the problem!!
Gary in SC
By Dave Ayoub
Ok i am not quick to jump on a forum and post a question without doing my own part and trying to research and solve the problem myself but I cannot find any definitive information anywhere about my problem. I have a Big Bear 350 that I picked up very cheap which had been sitting in a field for years. I am not new to building wheelers but this one has me beat. After rebuilding top end and replacing the carb it fires right up. The vin has some number worn off from being next to the shifter but from the parts in the clutch i assume it is early since 87 parts seem to be the only ones that match. Thats when the plot thickened.
Reverse works fine but when in the forward gears it would not go past 1st and was hard to get into neutral. ie. a it took a million clicks up to thump into 1 and as many down to find neutral. still never getting past 1st. within minutes i could hear metal screeching and whirling around in the clutch side of the motor. I took the cover off to find that 3 out of the 4 springs on the centrifugal clutch had broken and were shredded. Also the black mechanism that the pawl on shift shaft grabs moves was loose so it wasnt always grab to change the gear on the transmission. I tightened that mech, and replaced the springs assuming it would solve the problem since the gears were not actually changing from the lever and the carrier should obviously not only have 1 spring left.
After putting everything back together it did go into 1st fairly easy but then i again couldnt get it back to N without a million clicks down and couldnt get it to go past 1st. I did one time get it into a higher gear who knows what one but i gained some speed and dropped rpm.
If i jack both the front and the back wheels off the ground and run the motor it becomes much easier to shift and i can get it to run through the gears pretty well. Usually going into N without a huge fight. not perfect but it does hit neutral and roar while spinning the wheels instead of gain rpm and with the power.
I have tried every possible position on the clutch adjustment screw without any noticeable result. I think this could potentially be where my problem lies at this point.
does anyone know if the case is supposed to be threaded? because mine is not. obviously it seems as though it should be since every other bike ive touched has been. i even took the cover off my quadrunner to make sure it wasnt crazy.
when the screw is adjusted and the jam nut tightened the screw will just slide back out since there is no threading in the case. accomplishing nothing.
Does anyone have any insight on any of this? Are my plates stuck, Centrif clutch worn out, case stripped or something else crazy im over looking?
By Wolf Studios
Hi guys so I'm looking for any help or advice with a yamaha big bear 350 1997 (i think) it's fairly dirty and just been say for many years, boss says it's a non runner and I've tried and it will not start, ideally would love to do it up and get it running but have been told the engine has gone, cannot find a new engine anywhere. Anything I should check first before just taking the entire thing apart?
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