I have a 1987 big bear its been a really good bike there has never really been 2 big of problems with it till now- ive been workin on 4 wheelers 4 years and never came around something like this please help

its has good spark-good compression-and its getting gas good- and i checked the timing on it and its good-i clean the carb- what else could i do? i was running fine 2 weeks ago....thanks

 

Well you have 3 of the 4 requirements to make an engine run:

1. Compression
2. Spark
3. Gas
4. AIR!!!!!

It is possible that you are getting TO MUCH gas, causing it to flood; or maybe you think it is getting gas but really is not.... Here is what I would do:

1. Drain the gas tank
~pull the fuel pecock and check the filter... Replace is nessasary.

2. Re-clean the Carb
~Take every piece of it apart, shoot every little hole with B12 and compressed air. Just aviod hitting the floats.

3. Clean the Air filter
~Believe it or not this could be your problem. A dirty filter can cause problems later in the quads life as well.

4. Double check the Intake system
~An extreamly lean condition will not allow your quad to fire up. Make sure the carb fits snug in the intake boot, allong with the airfilter boot to the carb.

5. Change your spark plug
~Comon, they are cheap and good insurance

6. Make sure your battery is strong.
~Even with a some what strong sounding battery you could not be providing enough 'spin' to charge up the coil and get a good strong spark.

7. Try starting it with the pull cord
~My wolverine acted the same way. Pulled the cord and it would fire up. Turns out it was Stator going bad (and this was on a 2000). If it is your stator check out Ricky Stator They are much cheaper than OEM Yamaha stuff. Ok I did the hard part for you. Big Bear Stator

8. Purchase a repair manual.
~ TRUST ME!!!! They are usefull and have nearly all of the answers to your questions.

Ther are helpfull hints in the repair manual to test the "run" switch and what not. I did these tests and nothing helped. I hope your problem is not as big as a Stator, or even the ECM. Good luck with the Big Bear.

Also, your engine compression could be bad. That is a REALLY OLD MACHINE. My 87warrior had a well worn motor that needed some TLC. Your BB could have a worn cylinder, rings, valves not seatting correctly, leaking gaskets, or even plugged exhaust. My frist recomendation is to change the exhaust bearing.......[img]i/expressions/face-icon-small-happy.gif[/img]

 

Is the starting hard problem the only problem? Does it idle ok when running? Can the choke come off, and run while still cold? Any backfire or popping? how old is the gas?
Is everything stock and in place? any big exhaust leaks, air box lid on, etc

 

thanks guys-i pulled my 4-wheeler with another one- to get it started and i let it run for about 30 mins and its starting fine now--the battery must not of had enough sence its winter thanks again

 

In the future to immediately find out if the fuel system/carb etc. is the problem or not, shut off the fuel and drain carb bowl via the drain screw (in case it is a flooding problem.). Pull out old spark plug. Spin motor over to rid it of possible excessive fuel. Now either pour a few drops of fuel into the spark plug hole and install new plug or install new plug and shoot a few seconds of starting fluid (ether) into the air intake and now try starting the bike. You know you have fuel and fresh fuel too. No water or old fuel and not too much fuel since you drained the carb and shut the fuel off. You have a fresh plug. If it does not start the problem is probably not fuel related but if it does miraculously suddenly start you know you have a fuel system problem. Could be the carb being blocked, over full or bad fuel, blocked petcock, fuel filter etc. Anyway it removes the mystery of which path to follow troubleshooting.

 

hey great tip on that RickyStator website! Really good deal and they are a more powerful stator too. Thanks for the tip.